diff --git a/Library/Homebrew/test/formula_spec.rb b/Library/Homebrew/test/formula_spec.rb
new file mode 100644
index 0000000000..1e064912fa
--- /dev/null
+++ b/Library/Homebrew/test/formula_spec.rb
@@ -0,0 +1,1295 @@
+require "test/support/fixtures/testball"
+require "formula"
+
+RSpec::Matchers.alias_matcher :follow_installed_alias, :be_follow_installed_alias
+RSpec::Matchers.alias_matcher :have_any_version_installed, :be_any_version_installed
+RSpec::Matchers.alias_matcher :need_migration, :be_migration_needed
+
+RSpec::Matchers.alias_matcher :have_changed_installed_alias_target, :be_installed_alias_target_changed
+RSpec::Matchers.alias_matcher :supersede_an_installed_formula, :be_supersedes_an_installed_formula
+RSpec::Matchers.alias_matcher :have_changed_alias, :be_alias_changed
+
+RSpec::Matchers.alias_matcher :have_option_defined, :be_option_defined
+RSpec::Matchers.alias_matcher :have_post_install_defined, :be_post_install_defined
+RSpec::Matchers.alias_matcher :have_test_defined, :be_test_defined
+RSpec::Matchers.alias_matcher :pour_bottle, :be_pour_bottle
+
+describe Formula do
+  describe "::new" do
+    let(:klass) do
+      Class.new(described_class) do
+        url "http://example.com/foo-1.0.tar.gz"
+      end
+    end
+
+    let(:name) { "formula_name" }
+    let(:path) { Formulary.core_path(name) }
+    let(:spec) { :stable }
+    let(:alias_name) { "baz@1" }
+    let(:alias_path) { CoreTap.instance.alias_dir/alias_name }
+    let(:f) { klass.new(name, path, spec) }
+    let(:f_alias) { klass.new(name, path, spec, alias_path: alias_path) }
+
+    specify "formula instantiation" do
+      expect(f.name).to eq(name)
+      expect(f.specified_name).to eq(name)
+      expect(f.full_name).to eq(name)
+      expect(f.full_specified_name).to eq(name)
+      expect(f.path).to eq(path)
+      expect(f.alias_path).to be nil
+      expect(f.alias_name).to be nil
+      expect(f.full_alias_name).to be nil
+      expect { klass.new }.to raise_error(ArgumentError)
+    end
+
+    specify "formula instantiation with alias" do
+      expect(f_alias.name).to eq(name)
+      expect(f_alias.full_name).to eq(name)
+      expect(f_alias.path).to eq(path)
+      expect(f_alias.alias_path).to eq(alias_path)
+      expect(f_alias.alias_name).to eq(alias_name)
+      expect(f_alias.specified_name).to eq(alias_name)
+      expect(f_alias.full_alias_name).to eq(alias_name)
+      expect(f_alias.full_specified_name).to eq(alias_name)
+      expect { klass.new }.to raise_error(ArgumentError)
+    end
+
+    context "in a Tap" do
+      let(:tap) { Tap.new("foo", "bar") }
+      let(:path) { (tap.path/"Formula/#{name}.rb") }
+      let(:full_name) { "#{tap.user}/#{tap.repo}/#{name}" }
+      let(:full_alias_name) { "#{tap.user}/#{tap.repo}/#{alias_name}" }
+
+      specify "formula instantiation" do
+        expect(f.name).to eq(name)
+        expect(f.specified_name).to eq(name)
+        expect(f.full_name).to eq(full_name)
+        expect(f.full_specified_name).to eq(full_name)
+        expect(f.path).to eq(path)
+        expect(f.alias_path).to be nil
+        expect(f.alias_name).to be nil
+        expect(f.full_alias_name).to be nil
+        expect { klass.new }.to raise_error(ArgumentError)
+      end
+
+      specify "formula instantiation with alias" do
+        expect(f_alias.name).to eq(name)
+        expect(f_alias.full_name).to eq(full_name)
+        expect(f_alias.path).to eq(path)
+        expect(f_alias.alias_path).to eq(alias_path)
+        expect(f_alias.alias_name).to eq(alias_name)
+        expect(f_alias.specified_name).to eq(alias_name)
+        expect(f_alias.full_alias_name).to eq(full_alias_name)
+        expect(f_alias.full_specified_name).to eq(full_alias_name)
+        expect { klass.new }.to raise_error(ArgumentError)
+      end
+    end
+  end
+
+  describe "#follow_installed_alias?" do
+    let(:f) do
+      formula do
+        url "foo-1.0"
+      end
+    end
+
+    it "returns true by default" do
+      expect(f).to follow_installed_alias
+    end
+
+    it "can be set to true" do
+      f.follow_installed_alias = true
+      expect(f).to follow_installed_alias
+    end
+
+    it "can be set to false" do
+      f.follow_installed_alias = false
+      expect(f).not_to follow_installed_alias
+    end
+  end
+
+  example "installed alias with core" do
+    f = formula do
+      url "foo-1.0"
+    end
+
+    build_values_with_no_installed_alias = [
+      nil,
+      BuildOptions.new({}, {}),
+      Tab.new(source: { "path" => f.path.to_s }),
+    ]
+    build_values_with_no_installed_alias.each do |build|
+      f.build = build
+      expect(f.installed_alias_path).to be nil
+      expect(f.installed_alias_name).to be nil
+      expect(f.full_installed_alias_name).to be nil
+      expect(f.installed_specified_name).to eq(f.name)
+      expect(f.full_installed_specified_name).to eq(f.name)
+    end
+
+    alias_name = "bar"
+    alias_path = "#{CoreTap.instance.alias_dir}/#{alias_name}"
+
+    f.build = Tab.new(source: { "path" => alias_path })
+
+    expect(f.installed_alias_path).to eq(alias_path)
+    expect(f.installed_alias_name).to eq(alias_name)
+    expect(f.full_installed_alias_name).to eq(alias_name)
+    expect(f.installed_specified_name).to eq(alias_name)
+    expect(f.full_installed_specified_name).to eq(alias_name)
+  end
+
+  example "installed alias with tap" do
+    tap = Tap.new("user", "repo")
+    name = "foo"
+    path = "#{tap.path}/Formula/#{name}.rb"
+    f = formula name, path: path do
+      url "foo-1.0"
+    end
+
+    build_values_with_no_installed_alias = [nil, BuildOptions.new({}, {}), Tab.new(source: { "path" => f.path })]
+    build_values_with_no_installed_alias.each do |build|
+      f.build = build
+      expect(f.installed_alias_path).to be nil
+      expect(f.installed_alias_name).to be nil
+      expect(f.full_installed_alias_name).to be nil
+      expect(f.installed_specified_name).to eq(f.name)
+      expect(f.full_installed_specified_name).to eq(f.full_name)
+    end
+
+    alias_name = "bar"
+    full_alias_name = "#{tap.user}/#{tap.repo}/#{alias_name}"
+    alias_path = "#{tap.alias_dir}/#{alias_name}"
+
+    f.build = Tab.new(source: { "path" => alias_path })
+
+    expect(f.installed_alias_path).to eq(alias_path)
+    expect(f.installed_alias_name).to eq(alias_name)
+    expect(f.full_installed_alias_name).to eq(full_alias_name)
+    expect(f.installed_specified_name).to eq(alias_name)
+    expect(f.full_installed_specified_name).to eq(full_alias_name)
+  end
+
+  specify "#prefix" do
+    f = Testball.new
+    expect(f.prefix).to eq(HOMEBREW_CELLAR/f.name/"0.1")
+    expect(f.prefix).to be_kind_of(Pathname)
+  end
+
+  example "revised prefix" do
+    f = Class.new(Testball) { revision(1) }.new
+    expect(f.prefix).to eq(HOMEBREW_CELLAR/f.name/"0.1_1")
+  end
+
+  specify "#any_version_installed?" do
+    f = formula do
+      url "foo"
+      version "1.0"
+    end
+
+    expect(f).not_to have_any_version_installed
+
+    prefix = HOMEBREW_CELLAR/f.name/"0.1"
+    prefix.mkpath
+    FileUtils.touch prefix/Tab::FILENAME
+
+    expect(f).to have_any_version_installed
+  end
+
+  specify "#migration_needed" do
+    f = Testball.new("newname")
+    f.instance_variable_set(:@oldname, "oldname")
+    f.instance_variable_set(:@tap, CoreTap.instance)
+
+    oldname_prefix = (HOMEBREW_CELLAR/"oldname/2.20")
+    newname_prefix = (HOMEBREW_CELLAR/"newname/2.10")
+
+    oldname_prefix.mkpath
+    oldname_tab = Tab.empty
+    oldname_tab.tabfile = oldname_prefix/Tab::FILENAME
+    oldname_tab.write
+
+    expect(f).not_to need_migration
+
+    oldname_tab.tabfile.unlink
+    oldname_tab.source["tap"] = "homebrew/core"
+    oldname_tab.write
+
+    expect(f).to need_migration
+
+    newname_prefix.mkpath
+
+    expect(f).not_to need_migration
+  end
+
+  describe "#installed?" do
+    let(:f) { Testball.new }
+
+    it "returns false if the #installed_prefix is not a directory" do
+      allow(f).to receive(:installed_prefix).and_return(double(directory?: false))
+      expect(f).not_to be_installed
+    end
+
+    it "returns false if the #installed_prefix does not have children" do
+      allow(f).to receive(:installed_prefix).and_return(double(directory?: true, children: []))
+      expect(f).not_to be_installed
+    end
+
+    it "returns true if the #installed_prefix has children" do
+      allow(f).to receive(:installed_prefix).and_return(double(directory?: true, children: [double]))
+      expect(f).to be_installed
+    end
+  end
+
+  describe "#installed prefix" do
+    let(:f) do
+      formula do
+        url "foo"
+        version "1.9"
+
+        head "foo"
+
+        devel do
+          url "foo"
+          version "2.1-devel"
+        end
+      end
+    end
+
+    let(:stable_prefix) { HOMEBREW_CELLAR/f.name/f.version }
+    let(:devel_prefix) { HOMEBREW_CELLAR/f.name/f.devel.version }
+    let(:head_prefix) { HOMEBREW_CELLAR/f.name/f.head.version }
+
+    it "is the same as #prefix by default" do
+      expect(f.installed_prefix).to eq(f.prefix)
+    end
+
+    it "returns the stable prefix if it is installed" do
+      stable_prefix.mkpath
+      expect(f.installed_prefix).to eq(stable_prefix)
+    end
+
+    it "returns the devel prefix if it is installed" do
+      devel_prefix.mkpath
+      expect(f.installed_prefix).to eq(devel_prefix)
+    end
+
+    it "returns the head prefix if it is installed" do
+      head_prefix.mkpath
+      expect(f.installed_prefix).to eq(head_prefix)
+    end
+
+    it "returns the stable prefix if head is outdated" do
+      head_prefix.mkpath
+
+      tab = Tab.empty
+      tab.tabfile = head_prefix/Tab::FILENAME
+      tab.source["versions"] = { "stable" => "1.0" }
+      tab.write
+
+      expect(f.installed_prefix).to eq(stable_prefix)
+    end
+
+    it "returns the stable prefix if head and devel are outdated" do
+      head_prefix.mkpath
+
+      tab = Tab.empty
+      tab.tabfile = head_prefix/Tab::FILENAME
+      tab.source["versions"] = { "stable" => "1.9", "devel" => "2.0" }
+      tab.write
+
+      expect(f.installed_prefix).to eq(stable_prefix)
+    end
+
+    it "returns the devel prefix if the active specification is :devel" do
+      f.active_spec = :devel
+      expect(f.installed_prefix).to eq(devel_prefix)
+    end
+
+    it "returns the head prefix if the active specification is :head" do
+      f.active_spec = :head
+      expect(f.installed_prefix).to eq(head_prefix)
+    end
+  end
+
+  describe "#latest_head_prefix" do
+    let(:f) { Testball.new }
+
+    it "returns the latest head prefix" do
+      stamps_with_revisions = [
+        [111111, 1],
+        [222222, 0],
+        [222222, 1],
+        [222222, 2],
+      ]
+
+      stamps_with_revisions.each do |stamp, revision|
+        version = "HEAD-#{stamp}"
+        version << "_#{revision}" unless revision.zero?
+
+        prefix = f.rack/version
+        prefix.mkpath
+
+        tab = Tab.empty
+        tab.tabfile = prefix/Tab::FILENAME
+        tab.source_modified_time = stamp
+        tab.write
+      end
+
+      prefix = HOMEBREW_CELLAR/f.name/"HEAD-222222_2"
+
+      expect(f.latest_head_prefix).to eq(prefix)
+    end
+  end
+
+  specify "equality" do
+    x = Testball.new
+    y = Testball.new
+
+    expect(x).to eq(y)
+    expect(x).to eql(y)
+    expect(x.hash).to eq(y.hash)
+  end
+
+  specify "inequality" do
+    x = Testball.new("foo")
+    y = Testball.new("bar")
+
+    expect(x).not_to eq(y)
+    expect(x).not_to eql(y)
+    expect(x.hash).not_to eq(y.hash)
+  end
+
+  specify "comparison with non formula objects does not raise" do
+    expect(Object.new).not_to eq(Testball.new)
+  end
+
+  specify "#<=>" do
+    expect(Testball.new <=> Object.new).to be nil
+  end
+
+  describe "#installed_alias_path" do
+    example "alias paths with build options" do
+      alias_path = (CoreTap.instance.alias_dir/"another_name")
+
+      f = formula alias_path: alias_path do
+        url "foo-1.0"
+      end
+      f.build = BuildOptions.new({}, {})
+
+      expect(f.alias_path).to eq(alias_path)
+      expect(f.installed_alias_path).to be nil
+    end
+
+    example "alias paths with tab with non alias source path" do
+      alias_path = (CoreTap.instance.alias_dir/"another_name")
+      source_path = (CoreTap.instance.formula_dir/"another_other_name")
+
+      f = formula alias_path: alias_path do
+        url "foo-1.0"
+      end
+      f.build = Tab.new(source: { "path" => source_path.to_s })
+
+      expect(f.alias_path).to eq(alias_path)
+      expect(f.installed_alias_path).to be nil
+    end
+
+    example "alias paths with tab with alias source path" do
+      alias_path = (CoreTap.instance.alias_dir/"another_name")
+      source_path = (CoreTap.instance.alias_dir/"another_other_name")
+
+      f = formula alias_path: alias_path do
+        url "foo-1.0"
+      end
+      f.build = Tab.new(source: { "path" => source_path.to_s })
+
+      expect(f.alias_path).to eq(alias_path)
+      expect(f.installed_alias_path).to eq(source_path.to_s)
+    end
+  end
+
+  describe "::installed_with_alias_path" do
+    specify "with alias path with nil" do
+      expect(described_class.installed_with_alias_path(nil)).to be_empty
+    end
+
+    specify "with alias path with a path" do
+      alias_path = "#{CoreTap.instance.alias_dir}/alias"
+      different_alias_path = "#{CoreTap.instance.alias_dir}/another_alias"
+
+      formula_with_alias = formula "foo" do
+        url "foo-1.0"
+      end
+      formula_with_alias.build = Tab.empty
+      formula_with_alias.build.source["path"] = alias_path
+
+      formula_without_alias = formula "bar" do
+        url "bar-1.0"
+      end
+      formula_without_alias.build = Tab.empty
+      formula_without_alias.build.source["path"] = formula_without_alias.path.to_s
+
+      formula_with_different_alias = formula "baz" do
+        url "baz-1.0"
+      end
+      formula_with_different_alias.build = Tab.empty
+      formula_with_different_alias.build.source["path"] = different_alias_path
+
+      formulae = [
+        formula_with_alias,
+        formula_without_alias,
+        formula_with_different_alias,
+      ]
+
+      allow(described_class).to receive(:installed).and_return(formulae)
+
+      expect(described_class.installed_with_alias_path(alias_path))
+        .to eq([formula_with_alias])
+    end
+  end
+
+  specify "spec integration" do
+    f = formula do
+      homepage "http://example.com"
+
+      url "http://example.com/test-0.1.tbz"
+      mirror "http://example.org/test-0.1.tbz"
+      sha256 TEST_SHA256
+
+      head "http://example.com/test.git", tag: "foo"
+
+      devel do
+        url "http://example.com/test-0.2.tbz"
+        mirror "http://example.org/test-0.2.tbz"
+        sha256 TEST_SHA256
+      end
+    end
+
+    expect(f.homepage).to eq("http://example.com")
+    expect(f.version).to eq(Version.create("0.1"))
+    expect(f).to be_stable
+    expect(f.stable.version).to eq(Version.create("0.1"))
+    expect(f.devel.version).to eq(Version.create("0.2"))
+    expect(f.head.version).to eq(Version.create("HEAD"))
+  end
+
+  specify "#active_spec=" do
+    f = formula do
+      url "foo"
+      version "1.0"
+      revision 1
+
+      devel do
+        url "foo"
+        version "1.0beta"
+      end
+    end
+
+    expect(f.active_spec_sym).to eq(:stable)
+    expect(f.send(:active_spec)).to eq(f.stable)
+    expect(f.pkg_version.to_s).to eq("1.0_1")
+
+    f.active_spec = :devel
+
+    expect(f.active_spec_sym).to eq(:devel)
+    expect(f.send(:active_spec)).to eq(f.devel)
+    expect(f.pkg_version.to_s).to eq("1.0beta_1")
+    expect { f.active_spec = :head }.to raise_error(FormulaSpecificationError)
+  end
+
+  specify "class specs are always initialized" do
+    f = formula do
+      url "foo-1.0"
+    end
+
+    expect(f.class.stable).to be_kind_of(SoftwareSpec)
+    expect(f.class.devel).to be_kind_of(SoftwareSpec)
+    expect(f.class.head).to be_kind_of(SoftwareSpec)
+  end
+
+  specify "incomplete instance specs are not accessible" do
+    f = formula do
+      url "foo-1.0"
+    end
+
+    expect(f.devel).to be nil
+    expect(f.head).to be nil
+  end
+
+  it "honors attributes declared before specs" do
+    f = formula do
+      url "foo-1.0"
+
+      depends_on "foo"
+
+      devel do
+        url "foo-1.1"
+      end
+    end
+
+    expect(f.class.stable.deps.first.name).to eq("foo")
+    expect(f.class.devel.deps.first.name).to eq("foo")
+    expect(f.class.head.deps.first.name).to eq("foo")
+  end
+
+  describe "#pkg_version" do
+    specify "simple version" do
+      f = formula do
+        url "foo-1.0.bar"
+      end
+
+      expect(f.pkg_version).to eq(PkgVersion.parse("1.0"))
+    end
+
+    specify "version with revision" do
+      f = formula do
+        url "foo-1.0.bar"
+        revision 1
+      end
+
+      expect(f.pkg_version).to eq(PkgVersion.parse("1.0_1"))
+    end
+
+    specify "head uses revisions" do
+      f = formula "test", spec: :head do
+        url "foo-1.0.bar"
+        revision 1
+
+        head "foo"
+      end
+
+      expect(f.pkg_version).to eq(PkgVersion.parse("HEAD_1"))
+    end
+  end
+
+  specify "#update_head_version" do
+    f = formula do
+      head "foo", using: :git
+    end
+
+    cached_location = f.head.downloader.cached_location
+    cached_location.mkpath
+    cached_location.cd do
+      FileUtils.touch "LICENSE"
+
+      shutup do
+        system("git", "init")
+        system("git", "add", "--all")
+        system("git", "commit", "-m", "Initial commit")
+      end
+    end
+
+    f.update_head_version
+
+    expect(f.head.version).to eq(Version.create("HEAD-5658946"))
+  end
+
+  specify "legacy options" do
+    f = formula do
+      url "foo-1.0"
+
+      def options
+        [
+          ["--foo", "desc"],
+          ["--bar", "desc"],
+        ]
+      end
+
+      option("baz")
+    end
+
+    expect(f).to have_option_defined("foo")
+    expect(f).to have_option_defined("bar")
+    expect(f).to have_option_defined("baz")
+  end
+
+  specify "#desc" do
+    f = formula do
+      desc "a formula"
+
+      url "foo-1.0"
+    end
+
+    expect(f.desc).to eq("a formula")
+  end
+
+  specify "#post_install_defined?" do
+    f1 = formula do
+      url "foo-1.0"
+
+      def post_install
+        # do nothing
+      end
+    end
+
+    f2 = formula do
+      url "foo-1.0"
+    end
+
+    expect(f1).to have_post_install_defined
+    expect(f2).not_to have_post_install_defined
+  end
+
+  specify "#test_defined?" do
+    f1 = formula do
+      url "foo-1.0"
+
+      def test
+        # do nothing
+      end
+    end
+
+    f2 = formula do
+      url "foo-1.0"
+    end
+
+    expect(f1).to have_test_defined
+    expect(f2).not_to have_test_defined
+  end
+
+  specify "test fixtures" do
+    f1 = formula do
+      url "foo-1.0"
+    end
+
+    expect(f1.test_fixtures("foo")).to eq(Pathname.new("#{HOMEBREW_LIBRARY_PATH}/test/support/fixtures/foo"))
+  end
+
+  specify "dependencies" do
+    f1 = formula "f1" do
+      url "f1-1.0"
+    end
+
+    f2 = formula "f2" do
+      url "f2-1.0"
+    end
+
+    f3 = formula "f3" do
+      url "f3-1.0"
+
+      depends_on "f1" => :build
+      depends_on "f2"
+    end
+
+    f4 = formula "f4" do
+      url "f4-1.0"
+
+      depends_on "f1"
+    end
+
+    stub_formula_loader(f1)
+    stub_formula_loader(f2)
+    stub_formula_loader(f3)
+    stub_formula_loader(f4)
+
+    f5 = formula "f5" do
+      url "f5-1.0"
+
+      depends_on "f3" => :build
+      depends_on "f4"
+    end
+
+    expect(f5.deps.map(&:name)).to eq(["f3", "f4"])
+    expect(f5.recursive_dependencies.map(&:name)).to eq(["f1", "f2", "f3", "f4"])
+    expect(f5.runtime_dependencies.map(&:name)).to eq(["f1", "f4"])
+  end
+
+  specify "runtime dependencies with optional deps from tap" do
+    tap_loader = double
+
+    allow(tap_loader).to receive(:get_formula).and_raise(RuntimeError, "tried resolving tap formula")
+    allow(Formulary).to receive(:loader_for).with("foo/bar/f1", from: nil).and_return(tap_loader)
+    stub_formula_loader(formula("f2") { url("f2-1.0") }, "baz/qux/f2")
+
+    f3 = formula "f3" do
+      url "f3-1.0"
+
+      depends_on "foo/bar/f1" => :optional
+      depends_on "baz/qux/f2"
+    end
+
+    expect(f3.runtime_dependencies.map(&:name)).to eq(["baz/qux/f2"])
+
+    stub_formula_loader(formula("f1") { url("f1-1.0") }, "foo/bar/f1")
+    f3.build = BuildOptions.new(Options.create(["--with-f1"]), f3.options)
+
+    expect(f3.runtime_dependencies.map(&:name)).to eq(["foo/bar/f1", "baz/qux/f2"])
+  end
+
+  specify "requirements" do
+    f1 = formula "f1" do
+      url "f1-1"
+
+      depends_on :python
+      depends_on x11: :recommended
+      depends_on xcode: ["1.0", :optional]
+    end
+    stub_formula_loader(f1)
+
+    python = PythonRequirement.new
+    x11 = X11Requirement.new("x11", [:recommended])
+    xcode = XcodeRequirement.new(["1.0", :optional])
+
+    expect(Set.new(f1.recursive_requirements)).to eq(Set[python, x11])
+
+    f1.build = BuildOptions.new(["--with-xcode", "--without-x11"], f1.options)
+
+    expect(Set.new(f1.recursive_requirements)).to eq(Set[python, xcode])
+
+    f1.build = f1.stable.build
+    f2 = formula "f2" do
+      url "f2-1"
+
+      depends_on "f1"
+    end
+
+    expect(Set.new(f2.recursive_requirements)).to eq(Set[python, x11])
+    expect(Set.new(f2.recursive_requirements {})).to eq(Set[python, x11, xcode])
+
+    requirements = f2.recursive_requirements do |_dependent, requirement|
+      Requirement.prune if requirement.is_a?(PythonRequirement)
+    end
+
+    expect(Set.new(requirements)).to eq(Set[x11, xcode])
+  end
+
+  specify "#to_hash" do
+    f1 = formula "foo" do
+      url "foo-1.0"
+
+      bottle do
+        cellar(:any)
+        sha256(TEST_SHA256 => Utils::Bottles.tag)
+      end
+    end
+
+    h = f1.to_hash
+
+    expect(h).to be_a(Hash)
+    expect(h["name"]).to eq("foo")
+    expect(h["full_name"]).to eq("foo")
+    expect(h["versions"]["stable"]).to eq("1.0")
+    expect(h["versions"]["bottle"]).to be_truthy
+  end
+
+  describe "#eligible_kegs_for_cleanup" do
+    it "returns Kegs eligible for cleanup" do
+      f1 = Class.new(Testball) do
+        version("1.0")
+      end.new
+
+      f2 = Class.new(Testball) do
+        version("0.2")
+        version_scheme(1)
+      end.new
+
+      f3 = Class.new(Testball) do
+        version("0.3")
+        version_scheme(1)
+      end.new
+
+      f4 = Class.new(Testball) do
+        version("0.1")
+        version_scheme(2)
+      end.new
+
+      shutup do
+        [f1, f2, f3, f4].each do |f|
+          f.brew { f.install }
+          Tab.create(f, DevelopmentTools.default_compiler, :libcxx).write
+        end
+      end
+
+      expect(f1).to be_installed
+      expect(f2).to be_installed
+      expect(f3).to be_installed
+      expect(f4).to be_installed
+      expect(f3.eligible_kegs_for_cleanup.sort_by(&:version))
+        .to eq([f2, f1].map { |f| Keg.new(f.prefix) })
+    end
+
+    specify "with pinned Keg" do
+      f1 = Class.new(Testball) { version("0.1") }.new
+      f2 = Class.new(Testball) { version("0.2") }.new
+      f3 = Class.new(Testball) { version("0.3") }.new
+
+      shutup do
+        f1.brew { f1.install }
+        f1.pin
+        f2.brew { f2.install }
+        f3.brew { f3.install }
+      end
+
+      expect(f1.prefix).to eq((HOMEBREW_PINNED_KEGS/f1.name).resolved_path)
+      expect(f1).to be_installed
+      expect(f2).to be_installed
+      expect(f3).to be_installed
+      expect(shutup { f3.eligible_kegs_for_cleanup }).to eq([Keg.new(f2.prefix)])
+    end
+
+    specify "with HEAD installed" do
+      f = formula do
+        version("0.1")
+        head("foo")
+      end
+
+      stable_prefix = f.installed_prefix
+      stable_prefix.mkpath
+
+      [["000000_1", 1], ["111111", 2], ["111111_1", 2]].each do |pkg_version_suffix, stamp|
+        prefix = f.prefix("HEAD-#{pkg_version_suffix}")
+        prefix.mkpath
+        tab = Tab.empty
+        tab.tabfile = prefix/Tab::FILENAME
+        tab.source_modified_time = stamp
+        tab.write
+      end
+
+      eligible_kegs = f.installed_kegs - [Keg.new(f.prefix("HEAD-111111_1"))]
+      expect(f.eligible_kegs_for_cleanup).to eq(eligible_kegs)
+    end
+  end
+
+  describe "#pour_bottle?" do
+    it "returns false if set to false" do
+      f = formula "foo" do
+        url "foo-1.0"
+
+        def pour_bottle?
+          false
+        end
+      end
+
+      expect(f).not_to pour_bottle
+    end
+
+    it "returns true if set to true" do
+      f = formula "foo" do
+        url "foo-1.0"
+
+        def pour_bottle?
+          true
+        end
+      end
+
+      expect(f).to pour_bottle
+    end
+
+    it "returns false if set to false via DSL" do
+      f = formula "foo" do
+        url "foo-1.0"
+
+        pour_bottle? do
+          reason "false reason"
+          satisfy { (var == etc) }
+        end
+      end
+
+      expect(f).not_to pour_bottle
+    end
+
+    it "returns true if set to true via DSL" do
+      f = formula "foo" do
+        url "foo-1.0"
+
+        pour_bottle? do
+          reason "true reason"
+          satisfy { true }
+        end
+      end
+
+      expect(f).to pour_bottle
+    end
+  end
+
+  describe "alias changes" do
+    let(:f) do
+      formula "formula_name", alias_path: alias_path do
+        url "foo-1.0"
+      end
+    end
+
+    let(:new_formula) do
+      formula "new_formula_name", alias_path: alias_path do
+        url "foo-1.1"
+      end
+    end
+
+    let(:tab) { Tab.empty }
+    let(:alias_path) { "#{CoreTap.instance.alias_dir}/bar" }
+
+    before(:each) do
+      allow(described_class).to receive(:installed).and_return([f])
+
+      f.build = tab
+      new_formula.build = tab
+    end
+
+    specify "alias changes when not installed with alias" do
+      tab.source["path"] = Formulary.core_path(f.name).to_s
+
+      expect(f.current_installed_alias_target).to be nil
+      expect(f.latest_formula).to eq(f)
+      expect(f).not_to have_changed_installed_alias_target
+      expect(f).not_to supersede_an_installed_formula
+      expect(f).not_to have_changed_alias
+      expect(f.old_installed_formulae).to be_empty
+    end
+
+    specify "alias changes when not changed" do
+      tab.source["path"] = alias_path
+      stub_formula_loader(f, alias_path)
+
+      expect(f.current_installed_alias_target).to eq(f)
+      expect(f.latest_formula).to eq(f)
+      expect(f).not_to have_changed_installed_alias_target
+      expect(f).not_to supersede_an_installed_formula
+      expect(f).not_to have_changed_alias
+      expect(f.old_installed_formulae).to be_empty
+    end
+
+    specify "alias changes when new alias target" do
+      tab.source["path"] = alias_path
+      stub_formula_loader(new_formula, alias_path)
+
+      expect(f.current_installed_alias_target).to eq(new_formula)
+      expect(f.latest_formula).to eq(new_formula)
+      expect(f).to have_changed_installed_alias_target
+      expect(f).not_to supersede_an_installed_formula
+      expect(f).to have_changed_alias
+      expect(f.old_installed_formulae).to be_empty
+    end
+
+    specify "alias changes when old formulae installed" do
+      tab.source["path"] = alias_path
+      stub_formula_loader(new_formula, alias_path)
+
+      expect(new_formula.current_installed_alias_target).to eq(new_formula)
+      expect(new_formula.latest_formula).to eq(new_formula)
+      expect(new_formula).not_to have_changed_installed_alias_target
+      expect(new_formula).to supersede_an_installed_formula
+      expect(new_formula).to have_changed_alias
+      expect(new_formula.old_installed_formulae).to eq([f])
+    end
+  end
+
+  describe "#outdated_kegs" do
+    let(:outdated_prefix) { (HOMEBREW_CELLAR/"#{f.name}/1.11") }
+    let(:same_prefix) { (HOMEBREW_CELLAR/"#{f.name}/1.20") }
+    let(:greater_prefix) { (HOMEBREW_CELLAR/"#{f.name}/1.21") }
+    let(:head_prefix) { (HOMEBREW_CELLAR/"#{f.name}/HEAD") }
+    let(:old_alias_target_prefix) { (HOMEBREW_CELLAR/"#{old_formula.name}/1.0") }
+
+    let(:f) do
+      formula do
+        url "foo"
+        version "1.20"
+      end
+    end
+
+    let(:old_formula) do
+      formula "foo@1" do
+        url "foo-1.0"
+      end
+    end
+
+    let(:new_formula) do
+      formula "foo@2" do
+        url "foo-2.0"
+      end
+    end
+
+    let(:alias_path) { "#{f.tap.alias_dir}/bar" }
+
+    def setup_tab_for_prefix(prefix, options = {})
+      prefix.mkpath
+      tab = Tab.empty
+      tab.tabfile = prefix/Tab::FILENAME
+      tab.source["path"] = options[:path].to_s if options[:path]
+      tab.source["tap"] = options[:tap] if options[:tap]
+      tab.source["versions"] = options[:versions] if options[:versions]
+      tab.source_modified_time = options[:source_modified_time].to_i
+      tab.write unless options[:no_write]
+      tab
+    end
+
+    def reset_outdated_kegs
+      f.instance_variable_set(:@outdated_kegs, nil)
+    end
+
+    example "greater different tap installed" do
+      setup_tab_for_prefix(greater_prefix, tap: "user/repo")
+      expect(f.outdated_kegs).to be_empty
+    end
+
+    example "greater same tap installed" do
+      f.instance_variable_set(:@tap, CoreTap.instance)
+      setup_tab_for_prefix(greater_prefix, tap: "homebrew/core")
+      expect(f.outdated_kegs).to be_empty
+    end
+
+    example "outdated different tap installed" do
+      setup_tab_for_prefix(outdated_prefix, tap: "user/repo")
+      expect(f.outdated_kegs).not_to be_empty
+    end
+
+    example "outdated same tap installed" do
+      f.instance_variable_set(:@tap, CoreTap.instance)
+      setup_tab_for_prefix(outdated_prefix, tap: "homebrew/core")
+      expect(f.outdated_kegs).not_to be_empty
+    end
+
+    example "outdated follow alias and alias unchanged" do
+      f.follow_installed_alias = true
+      f.build = setup_tab_for_prefix(same_prefix, path: alias_path)
+      stub_formula_loader(f, alias_path)
+      expect(f.outdated_kegs).to be_empty
+    end
+
+    example "outdated follow alias and alias changed and new target not installed" do
+      f.follow_installed_alias = true
+      f.build = setup_tab_for_prefix(same_prefix, path: alias_path)
+      stub_formula_loader(new_formula, alias_path)
+      expect(f.outdated_kegs).not_to be_empty
+    end
+
+    example "outdated follow alias and alias changed and new target installed" do
+      f.follow_installed_alias = true
+      f.build = setup_tab_for_prefix(same_prefix, path: alias_path)
+      stub_formula_loader(new_formula, alias_path)
+      setup_tab_for_prefix(new_formula.prefix)
+      expect(f.outdated_kegs).to be_empty
+    end
+
+    example "outdated no follow alias and alias unchanged" do
+      f.follow_installed_alias = false
+      f.build = setup_tab_for_prefix(same_prefix, path: alias_path)
+      stub_formula_loader(f, alias_path)
+      expect(f.outdated_kegs).to be_empty
+    end
+
+    example "outdated no follow alias and alias changed" do
+      f.follow_installed_alias = false
+      f.build = setup_tab_for_prefix(same_prefix, path: alias_path)
+
+      f2 = formula "foo@2" do
+        url "foo-2.0"
+      end
+
+      stub_formula_loader(f2, alias_path)
+      expect(f.outdated_kegs).to be_empty
+    end
+
+    example "outdated old alias targets installed" do
+      f = formula alias_path: alias_path do
+        url "foo-1.0"
+      end
+
+      tab = setup_tab_for_prefix(old_alias_target_prefix, path: alias_path)
+      old_formula.build = tab
+      allow(described_class).to receive(:installed).and_return([old_formula])
+      expect(f.outdated_kegs).not_to be_empty
+    end
+
+    example "outdated old alias targets not installed" do
+      f = formula alias_path: alias_path do
+        url "foo-1.0"
+      end
+
+      tab = setup_tab_for_prefix(old_alias_target_prefix, path: old_formula.path)
+      old_formula.build = tab
+      allow(described_class).to receive(:installed).and_return([old_formula])
+      expect(f.outdated_kegs).to be_empty
+    end
+
+    example "outdated same head installed" do
+      f.instance_variable_set(:@tap, CoreTap.instance)
+      setup_tab_for_prefix(head_prefix, tap: "homebrew/core")
+      expect(f.outdated_kegs).to be_empty
+    end
+
+    example "outdated different head installed" do
+      f.instance_variable_set(:@tap, CoreTap.instance)
+      setup_tab_for_prefix(head_prefix, tap: "user/repo")
+      expect(f.outdated_kegs).to be_empty
+    end
+
+    example "outdated mixed taps greater version installed" do
+      f.instance_variable_set(:@tap, CoreTap.instance)
+      setup_tab_for_prefix(outdated_prefix, tap: "homebrew/core")
+      setup_tab_for_prefix(greater_prefix, tap: "user/repo")
+
+      expect(f.outdated_kegs).to be_empty
+
+      setup_tab_for_prefix(greater_prefix, tap: "homebrew/core")
+      reset_outdated_kegs
+
+      expect(f.outdated_kegs).to be_empty
+    end
+
+    example "outdated mixed taps outdated version installed" do
+      f.instance_variable_set(:@tap, CoreTap.instance)
+
+      extra_outdated_prefix = HOMEBREW_CELLAR/f.name/"1.0"
+
+      setup_tab_for_prefix(outdated_prefix)
+      setup_tab_for_prefix(extra_outdated_prefix, tap: "homebrew/core")
+      reset_outdated_kegs
+
+      expect(f.outdated_kegs).not_to be_empty
+
+      setup_tab_for_prefix(outdated_prefix, tap: "user/repo")
+      reset_outdated_kegs
+
+      expect(f.outdated_kegs).not_to be_empty
+    end
+
+    example "outdated same version tap installed" do
+      f.instance_variable_set(:@tap, CoreTap.instance)
+      setup_tab_for_prefix(same_prefix, tap: "homebrew/core")
+
+      expect(f.outdated_kegs).to be_empty
+
+      setup_tab_for_prefix(same_prefix, tap: "user/repo")
+      reset_outdated_kegs
+
+      expect(f.outdated_kegs).to be_empty
+    end
+
+    example "outdated installed head less than stable" do
+      tab = setup_tab_for_prefix(head_prefix, versions: { "stable" => "1.0" })
+
+      expect(f.outdated_kegs).not_to be_empty
+
+      tab.source["versions"] = { "stable" => f.version.to_s }
+      tab.write
+      reset_outdated_kegs
+
+      expect(f.outdated_kegs).to be_empty
+    end
+
+    describe ":fetch_head" do
+      let(:f) do
+        repo = testball_repo
+        formula "testball" do
+          url "foo"
+          version "2.10"
+          head "file://#{repo}", using: :git
+        end
+      end
+      let(:testball_repo) { HOMEBREW_PREFIX/"testball_repo" }
+
+      example do
+        begin
+          outdated_stable_prefix = HOMEBREW_CELLAR/"testball/1.0"
+          head_prefix_a = HOMEBREW_CELLAR/"testball/HEAD"
+          head_prefix_b = HOMEBREW_CELLAR/"testball/HEAD-aaaaaaa_1"
+          head_prefix_c = HOMEBREW_CELLAR/"testball/HEAD-18a7103"
+
+          setup_tab_for_prefix(outdated_stable_prefix)
+          tab_a = setup_tab_for_prefix(head_prefix_a, versions: { "stable" => "1.0" })
+          setup_tab_for_prefix(head_prefix_b)
+
+          testball_repo.mkdir
+          testball_repo.cd do
+            FileUtils.touch "LICENSE"
+
+            shutup do
+              system("git", "init")
+              system("git", "add", "--all")
+              system("git", "commit", "-m", "Initial commit")
+            end
+          end
+
+          expect(f.outdated_kegs(fetch_head: true)).not_to be_empty
+
+          tab_a.source["versions"] = { "stable" => f.version.to_s }
+          tab_a.write
+          reset_outdated_kegs
+          expect(f.outdated_kegs(fetch_head: true)).not_to be_empty
+
+          head_prefix_a.rmtree
+          reset_outdated_kegs
+          expect(f.outdated_kegs(fetch_head: true)).not_to be_empty
+
+          setup_tab_for_prefix(head_prefix_c, source_modified_time: 1)
+          reset_outdated_kegs
+          expect(f.outdated_kegs(fetch_head: true)).to be_empty
+        ensure
+          testball_repo.rmtree if testball_repo.exist?
+        end
+      end
+    end
+
+    describe "with changed version scheme" do
+      let(:f) do
+        formula "testball" do
+          url "foo"
+          version "20141010"
+          version_scheme 1
+        end
+      end
+
+      example do
+        prefix = HOMEBREW_CELLAR/"testball/0.1"
+        setup_tab_for_prefix(prefix, versions: { "stable" => "0.1" })
+
+        expect(f.outdated_kegs).not_to be_empty
+      end
+    end
+
+    describe "with mixed version schemes" do
+      let(:f) do
+        formula "testball" do
+          url "foo"
+          version "20141010"
+          version_scheme 3
+        end
+      end
+
+      example do
+        prefix_a = HOMEBREW_CELLAR/"testball/20141009"
+        setup_tab_for_prefix(prefix_a, versions: { "stable" => "20141009", "version_scheme" => 1 })
+
+        prefix_b = HOMEBREW_CELLAR/"testball/2.14"
+        setup_tab_for_prefix(prefix_b, versions: { "stable" => "2.14", "version_scheme" => 2 })
+
+        expect(f.outdated_kegs).not_to be_empty
+        reset_outdated_kegs
+
+        prefix_c = HOMEBREW_CELLAR/"testball/20141009"
+        setup_tab_for_prefix(prefix_c, versions: { "stable" => "20141009", "version_scheme" => 3 })
+
+        expect(f.outdated_kegs).not_to be_empty
+        reset_outdated_kegs
+
+        prefix_d = HOMEBREW_CELLAR/"testball/20141011"
+        setup_tab_for_prefix(prefix_d, versions: { "stable" => "20141009", "version_scheme" => 3 })
+        expect(f.outdated_kegs).to be_empty
+      end
+    end
+
+    describe "with version scheme" do
+      let(:f) do
+        formula "testball" do
+          url "foo"
+          version "1.0"
+          version_scheme 2
+        end
+      end
+
+      example do
+        head_prefix = HOMEBREW_CELLAR/"testball/HEAD"
+
+        setup_tab_for_prefix(head_prefix, versions: { "stable" => "1.0", "version_scheme" => 1 })
+        expect(f.outdated_kegs).not_to be_empty
+
+        reset_outdated_kegs
+        head_prefix.rmtree
+
+        setup_tab_for_prefix(head_prefix, versions: { "stable" => "1.0", "version_scheme" => 2 })
+        expect(f.outdated_kegs).to be_empty
+      end
+    end
+  end
+end
diff --git a/Library/Homebrew/test/formula_test.rb b/Library/Homebrew/test/formula_test.rb
deleted file mode 100644
index 318175d49c..0000000000
--- a/Library/Homebrew/test/formula_test.rb
+++ /dev/null
@@ -1,1205 +0,0 @@
-require "testing_env"
-require "test/support/fixtures/testball"
-require "formula"
-
-class FormulaTests < Homebrew::TestCase
-  def test_formula_instantiation
-    klass = Class.new(Formula) { url "http://example.com/foo-1.0.tar.gz" }
-    name = "formula_name"
-    path = Formulary.core_path(name)
-    spec = :stable
-
-    f = klass.new(name, path, spec)
-    assert_equal name, f.name
-    assert_equal name, f.specified_name
-    assert_equal name, f.full_name
-    assert_equal name, f.full_specified_name
-    assert_equal path, f.path
-    assert_nil f.alias_path
-    assert_nil f.alias_name
-    assert_nil f.full_alias_name
-    assert_raises(ArgumentError) { klass.new }
-  end
-
-  def test_formula_instantiation_with_alias
-    klass = Class.new(Formula) { url "http://example.com/foo-1.0.tar.gz" }
-    name = "formula_name"
-    path = Formulary.core_path(name)
-    spec = :stable
-    alias_name = "baz@1"
-    alias_path = CoreTap.instance.alias_dir/alias_name
-
-    f = klass.new(name, path, spec, alias_path: alias_path)
-    assert_equal name, f.name
-    assert_equal name, f.full_name
-    assert_equal path, f.path
-    assert_equal alias_path, f.alias_path
-    assert_equal alias_name, f.alias_name
-    assert_equal alias_name, f.specified_name
-    assert_equal alias_name, f.full_alias_name
-    assert_equal alias_name, f.full_specified_name
-    assert_raises(ArgumentError) { klass.new }
-  end
-
-  def test_tap_formula_instantiation
-    tap = Tap.new("foo", "bar")
-    klass = Class.new(Formula) { url "baz-1.0" }
-    name = "baz"
-    full_name = "#{tap.user}/#{tap.repo}/#{name}"
-    path = tap.path/"Formula/#{name}.rb"
-    spec = :stable
-
-    f = klass.new(name, path, spec)
-    assert_equal name, f.name
-    assert_equal name, f.specified_name
-    assert_equal full_name, f.full_name
-    assert_equal full_name, f.full_specified_name
-    assert_equal path, f.path
-    assert_nil f.alias_path
-    assert_nil f.alias_name
-    assert_nil f.full_alias_name
-    assert_raises(ArgumentError) { klass.new }
-  end
-
-  def test_tap_formula_instantiation_with_alias
-    tap = Tap.new("foo", "bar")
-    klass = Class.new(Formula) { url "baz-1.0" }
-    name = "baz"
-    full_name = "#{tap.user}/#{tap.repo}/#{name}"
-    path = tap.path/"Formula/#{name}.rb"
-    spec = :stable
-    alias_name = "baz@1"
-    full_alias_name = "#{tap.user}/#{tap.repo}/#{alias_name}"
-    alias_path = CoreTap.instance.alias_dir/alias_name
-
-    f = klass.new(name, path, spec, alias_path: alias_path)
-    assert_equal name, f.name
-    assert_equal full_name, f.full_name
-    assert_equal path, f.path
-    assert_equal alias_path, f.alias_path
-    assert_equal alias_name, f.alias_name
-    assert_equal alias_name, f.specified_name
-    assert_equal full_alias_name, f.full_alias_name
-    assert_equal full_alias_name, f.full_specified_name
-    assert_raises(ArgumentError) { klass.new }
-  end
-
-  def test_follow_installed_alias
-    f = formula { url "foo-1.0" }
-    assert_predicate f, :follow_installed_alias?
-
-    f.follow_installed_alias = true
-    assert_predicate f, :follow_installed_alias?
-
-    f.follow_installed_alias = false
-    refute_predicate f, :follow_installed_alias?
-  end
-
-  def test_installed_alias_with_core
-    f = formula { url "foo-1.0" }
-
-    build_values_with_no_installed_alias = [
-      nil,
-      BuildOptions.new({}, {}),
-      Tab.new(source: { "path" => f.path.to_s }),
-    ]
-
-    build_values_with_no_installed_alias.each do |build|
-      f.build = build
-      assert_nil f.installed_alias_path
-      assert_nil f.installed_alias_name
-      assert_nil f.full_installed_alias_name
-      assert_equal f.name, f.installed_specified_name
-      assert_equal f.name, f.full_installed_specified_name
-    end
-
-    alias_name = "bar"
-    alias_path = "#{CoreTap.instance.alias_dir}/#{alias_name}"
-    f.build = Tab.new(source: { "path" => alias_path })
-    assert_equal alias_path, f.installed_alias_path
-    assert_equal alias_name, f.installed_alias_name
-    assert_equal alias_name, f.full_installed_alias_name
-    assert_equal alias_name, f.installed_specified_name
-    assert_equal alias_name, f.full_installed_specified_name
-  end
-
-  def test_installed_alias_with_tap
-    tap = Tap.new("user", "repo")
-    name = "foo"
-    path = "#{tap.path}/Formula/#{name}.rb"
-    f = formula(name, path) { url "foo-1.0" }
-
-    build_values_with_no_installed_alias = [
-      nil,
-      BuildOptions.new({}, {}),
-      Tab.new(source: { "path" => f.path }),
-    ]
-
-    build_values_with_no_installed_alias.each do |build|
-      f.build = build
-      assert_nil f.installed_alias_path
-      assert_nil f.installed_alias_name
-      assert_nil f.full_installed_alias_name
-      assert_equal f.name, f.installed_specified_name
-      assert_equal f.full_name, f.full_installed_specified_name
-    end
-
-    alias_name = "bar"
-    full_alias_name = "#{tap.user}/#{tap.repo}/#{alias_name}"
-    alias_path = "#{tap.alias_dir}/#{alias_name}"
-    f.build = Tab.new(source: { "path" => alias_path })
-    assert_equal alias_path, f.installed_alias_path
-    assert_equal alias_name, f.installed_alias_name
-    assert_equal full_alias_name, f.full_installed_alias_name
-    assert_equal alias_name, f.installed_specified_name
-    assert_equal full_alias_name, f.full_installed_specified_name
-  end
-
-  def test_prefix
-    f = Testball.new
-    assert_equal HOMEBREW_CELLAR/f.name/"0.1", f.prefix
-    assert_kind_of Pathname, f.prefix
-  end
-
-  def test_revised_prefix
-    f = Class.new(Testball) { revision 1 }.new
-    assert_equal HOMEBREW_CELLAR/f.name/"0.1_1", f.prefix
-  end
-
-  def test_any_version_installed?
-    f = formula do
-      url "foo"
-      version "1.0"
-    end
-    refute_predicate f, :any_version_installed?
-    prefix = HOMEBREW_CELLAR+f.name+"0.1"
-    prefix.mkpath
-    FileUtils.touch prefix+Tab::FILENAME
-    assert_predicate f, :any_version_installed?
-  end
-
-  def test_migration_needed
-    f = Testball.new("newname")
-    f.instance_variable_set(:@oldname, "oldname")
-    f.instance_variable_set(:@tap, CoreTap.instance)
-
-    oldname_prefix = HOMEBREW_CELLAR/"oldname/2.20"
-    newname_prefix = HOMEBREW_CELLAR/"newname/2.10"
-    oldname_prefix.mkpath
-    oldname_tab = Tab.empty
-    oldname_tab.tabfile = oldname_prefix.join("INSTALL_RECEIPT.json")
-    oldname_tab.write
-
-    refute_predicate f, :migration_needed?
-
-    oldname_tab.tabfile.unlink
-    oldname_tab.source["tap"] = "homebrew/core"
-    oldname_tab.write
-
-    assert_predicate f, :migration_needed?
-
-    newname_prefix.mkpath
-
-    refute_predicate f, :migration_needed?
-  end
-
-  def test_installed?
-    f = Testball.new
-    f.stubs(:installed_prefix).returns(stub(directory?: false))
-    refute_predicate f, :installed?
-
-    f.stubs(:installed_prefix).returns(
-      stub(directory?: true, children: []),
-    )
-    refute_predicate f, :installed?
-
-    f.stubs(:installed_prefix).returns(
-      stub(directory?: true, children: [stub]),
-    )
-    assert_predicate f, :installed?
-  end
-
-  def test_installed_prefix
-    f = Testball.new
-    assert_equal f.prefix, f.installed_prefix
-  end
-
-  def test_installed_prefix_head_installed
-    f = formula do
-      head "foo"
-      devel do
-        url "foo"
-        version "1.0"
-      end
-    end
-    prefix = HOMEBREW_CELLAR+f.name+f.head.version
-    prefix.mkpath
-    assert_equal prefix, f.installed_prefix
-  end
-
-  def test_installed_prefix_devel_installed
-    f = formula do
-      head "foo"
-      devel do
-        url "foo"
-        version "1.0"
-      end
-    end
-    prefix = HOMEBREW_CELLAR+f.name+f.devel.version
-    prefix.mkpath
-    assert_equal prefix, f.installed_prefix
-  end
-
-  def test_installed_prefix_stable_installed
-    f = formula do
-      head "foo"
-      devel do
-        url "foo"
-        version "1.0-devel"
-      end
-    end
-    prefix = HOMEBREW_CELLAR+f.name+f.version
-    prefix.mkpath
-    assert_equal prefix, f.installed_prefix
-  end
-
-  def test_installed_prefix_outdated_stable_head_installed
-    f = formula do
-      url "foo"
-      version "1.9"
-      head "foo"
-    end
-
-    head_prefix = HOMEBREW_CELLAR/"#{f.name}/HEAD"
-    head_prefix.mkpath
-    tab = Tab.empty
-    tab.tabfile = head_prefix.join("INSTALL_RECEIPT.json")
-    tab.source["versions"] = { "stable" => "1.0" }
-    tab.write
-
-    assert_equal HOMEBREW_CELLAR/"#{f.name}/#{f.version}", f.installed_prefix
-  end
-
-  def test_installed_prefix_outdated_devel_head_installed
-    f = formula do
-      url "foo"
-      version "1.9"
-      devel do
-        url "foo"
-        version "2.1"
-      end
-    end
-
-    head_prefix = HOMEBREW_CELLAR/"#{f.name}/HEAD"
-    head_prefix.mkpath
-    tab = Tab.empty
-    tab.tabfile = head_prefix.join("INSTALL_RECEIPT.json")
-    tab.source["versions"] = { "stable" => "1.9", "devel" => "2.0" }
-    tab.write
-
-    assert_equal HOMEBREW_CELLAR/"#{f.name}/#{f.version}", f.installed_prefix
-  end
-
-  def test_installed_prefix_head
-    f = formula("test", Pathname.new(__FILE__).expand_path, :head) do
-      head "foo"
-      devel do
-        url "foo"
-        version "1.0-devel"
-      end
-    end
-    prefix = HOMEBREW_CELLAR+f.name+f.head.version
-    assert_equal prefix, f.installed_prefix
-  end
-
-  def test_installed_prefix_devel
-    f = formula("test", Pathname.new(__FILE__).expand_path, :devel) do
-      head "foo"
-      devel do
-        url "foo"
-        version "1.0-devel"
-      end
-    end
-    prefix = HOMEBREW_CELLAR+f.name+f.devel.version
-    assert_equal prefix, f.installed_prefix
-  end
-
-  def test_latest_head_prefix
-    f = Testball.new
-
-    stamps_with_revisions = [[111111, 1], [222222, 1], [222222, 2], [222222, 0]]
-
-    stamps_with_revisions.each do |stamp, revision|
-      version = "HEAD-#{stamp}"
-      version += "_#{revision}" if revision > 0
-      prefix = f.rack.join(version)
-      prefix.mkpath
-
-      tab = Tab.empty
-      tab.tabfile = prefix.join("INSTALL_RECEIPT.json")
-      tab.source_modified_time = stamp
-      tab.write
-    end
-
-    prefix = HOMEBREW_CELLAR/"#{f.name}/HEAD-222222_2"
-    assert_equal prefix, f.latest_head_prefix
-  end
-
-  def test_equality
-    x = Testball.new
-    y = Testball.new
-    assert_equal x, y
-    assert_eql x, y
-    assert_equal x.hash, y.hash
-  end
-
-  def test_inequality
-    x = Testball.new("foo")
-    y = Testball.new("bar")
-    refute_equal x, y
-    refute_eql x, y
-    refute_equal x.hash, y.hash
-  end
-
-  def test_comparison_with_non_formula_objects_does_not_raise
-    refute_equal Testball.new, Object.new
-  end
-
-  def test_sort_operator
-    assert_nil Testball.new <=> Object.new
-  end
-
-  def test_alias_paths_with_build_options
-    alias_path = CoreTap.instance.alias_dir/"another_name"
-    f = formula(alias_path: alias_path) { url "foo-1.0" }
-    f.build = BuildOptions.new({}, {})
-    assert_equal alias_path, f.alias_path
-    assert_nil f.installed_alias_path
-  end
-
-  def test_alias_paths_with_tab_with_non_alias_source_path
-    alias_path = CoreTap.instance.alias_dir/"another_name"
-    source_path = CoreTap.instance.formula_dir/"another_other_name"
-    f = formula(alias_path: alias_path) { url "foo-1.0" }
-    f.build = Tab.new(source: { "path" => source_path.to_s })
-    assert_equal alias_path, f.alias_path
-    assert_nil f.installed_alias_path
-  end
-
-  def test_alias_paths_with_tab_with_alias_source_path
-    alias_path = CoreTap.instance.alias_dir/"another_name"
-    source_path = CoreTap.instance.alias_dir/"another_other_name"
-    f = formula(alias_path: alias_path) { url "foo-1.0" }
-    f.build = Tab.new(source: { "path" => source_path.to_s })
-    assert_equal alias_path, f.alias_path
-    assert_equal source_path.to_s, f.installed_alias_path
-  end
-
-  def test_installed_with_alias_path_with_nil
-    assert_predicate Formula.installed_with_alias_path(nil), :empty?
-  end
-
-  def test_installed_with_alias_path_with_a_path
-    alias_path = "#{CoreTap.instance.alias_dir}/alias"
-    different_alias_path = "#{CoreTap.instance.alias_dir}/another_alias"
-
-    formula_with_alias = formula("foo") { url "foo-1.0" }
-    formula_with_alias.build = Tab.empty
-    formula_with_alias.build.source["path"] = alias_path
-
-    formula_without_alias = formula("bar") { url "bar-1.0" }
-    formula_without_alias.build = Tab.empty
-    formula_without_alias.build.source["path"] = formula_without_alias.path.to_s
-
-    formula_with_different_alias = formula("baz") { url "baz-1.0" }
-    formula_with_different_alias.build = Tab.empty
-    formula_with_different_alias.build.source["path"] = different_alias_path
-
-    formulae = [
-      formula_with_alias,
-      formula_without_alias,
-      formula_with_different_alias,
-    ]
-
-    Formula.stubs(:installed).returns(formulae)
-    assert_equal [formula_with_alias], Formula.installed_with_alias_path(alias_path)
-  end
-
-  def test_formula_spec_integration
-    f = formula do
-      homepage "http://example.com"
-      url "http://example.com/test-0.1.tbz"
-      mirror "http://example.org/test-0.1.tbz"
-      sha256 TEST_SHA256
-
-      head "http://example.com/test.git", tag: "foo"
-
-      devel do
-        url "http://example.com/test-0.2.tbz"
-        mirror "http://example.org/test-0.2.tbz"
-        sha256 TEST_SHA256
-      end
-    end
-
-    assert_equal "http://example.com", f.homepage
-    assert_version_equal "0.1", f.version
-    assert_predicate f, :stable?
-
-    assert_version_equal "0.1", f.stable.version
-    assert_version_equal "0.2", f.devel.version
-    assert_version_equal "HEAD", f.head.version
-  end
-
-  def test_formula_active_spec=
-    f = formula do
-      url "foo"
-      version "1.0"
-      revision 1
-
-      devel do
-        url "foo"
-        version "1.0beta"
-      end
-    end
-    assert_equal :stable, f.active_spec_sym
-    assert_equal f.stable, f.send(:active_spec)
-    assert_equal "1.0_1", f.pkg_version.to_s
-    f.active_spec = :devel
-    assert_equal :devel, f.active_spec_sym
-    assert_equal f.devel, f.send(:active_spec)
-    assert_equal "1.0beta_1", f.pkg_version.to_s
-    assert_raises(FormulaSpecificationError) { f.active_spec = :head }
-  end
-
-  def test_path
-    name = "foo-bar"
-    assert_equal Pathname.new("#{HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core/Formula/#{name}.rb"), Formulary.core_path(name)
-  end
-
-  def test_class_specs_are_always_initialized
-    f = formula { url "foo-1.0" }
-
-    %w[stable devel head].each do |spec|
-      assert_kind_of SoftwareSpec, f.class.send(spec)
-    end
-  end
-
-  def test_incomplete_instance_specs_are_not_accessible
-    f = formula { url "foo-1.0" }
-
-    %w[devel head].each { |spec| assert_nil f.send(spec) }
-  end
-
-  def test_honors_attributes_declared_before_specs
-    f = formula do
-      url "foo-1.0"
-      depends_on "foo"
-      devel { url "foo-1.1" }
-    end
-
-    %w[stable devel head].each do |spec|
-      assert_equal "foo", f.class.send(spec).deps.first.name
-    end
-  end
-
-  def test_simple_version
-    assert_equal PkgVersion.parse("1.0"), formula { url "foo-1.0.bar" }.pkg_version
-  end
-
-  def test_version_with_revision
-    f = formula do
-      url "foo-1.0.bar"
-      revision 1
-    end
-
-    assert_equal PkgVersion.parse("1.0_1"), f.pkg_version
-  end
-
-  def test_head_uses_revisions
-    f = formula("test", Pathname.new(__FILE__).expand_path, :head) do
-      url "foo-1.0.bar"
-      revision 1
-      head "foo"
-    end
-
-    assert_equal PkgVersion.parse("HEAD_1"), f.pkg_version
-  end
-
-  def test_update_head_version
-    f = formula do
-      head "foo", using: :git
-    end
-
-    cached_location = f.head.downloader.cached_location
-    cached_location.mkpath
-
-    cached_location.cd do
-      FileUtils.touch "LICENSE"
-      shutup do
-        system "git", "init"
-        system "git", "add", "--all"
-        system "git", "commit", "-m", "Initial commit"
-      end
-    end
-
-    f.update_head_version
-    assert_equal Version.create("HEAD-5658946"), f.head.version
-  end
-
-  def test_legacy_options
-    f = formula do
-      url "foo-1.0"
-
-      def options
-        [["--foo", "desc"], ["--bar", "desc"]]
-      end
-
-      option "baz"
-    end
-
-    assert f.option_defined?("foo")
-    assert f.option_defined?("bar")
-    assert f.option_defined?("baz")
-  end
-
-  def test_desc
-    f = formula do
-      desc "a formula"
-      url "foo-1.0"
-    end
-
-    assert_equal "a formula", f.desc
-  end
-
-  def test_post_install_defined
-    f1 = formula do
-      url "foo-1.0"
-
-      def post_install; end
-    end
-
-    f2 = formula do
-      url "foo-1.0"
-    end
-
-    assert f1.post_install_defined?
-    refute f2.post_install_defined?
-  end
-
-  def test_test_defined
-    f1 = formula do
-      url "foo-1.0"
-
-      def test; end
-    end
-
-    f2 = formula do
-      url "foo-1.0"
-    end
-
-    assert f1.test_defined?
-    refute f2.test_defined?
-  end
-
-  def test_test_fixtures
-    f1 = formula do
-      url "foo-1.0"
-    end
-
-    assert_equal Pathname.new("#{HOMEBREW_LIBRARY_PATH}/test/support/fixtures/foo"),
-      f1.test_fixtures("foo")
-  end
-
-  def test_dependencies
-    stub_formula_loader formula("f1") { url "f1-1.0" }
-    stub_formula_loader formula("f2") { url "f2-1.0" }
-
-    f3 = formula("f3") do
-      url "f3-1.0"
-      depends_on "f1" => :build
-      depends_on "f2"
-    end
-    stub_formula_loader f3
-
-    f4 = formula("f4") do
-      url "f4-1.0"
-      depends_on "f1"
-    end
-    stub_formula_loader f4
-
-    f5 = formula("f5") do
-      url "f5-1.0"
-      depends_on "f3" => :build
-      depends_on "f4"
-    end
-
-    assert_equal %w[f3 f4], f5.deps.map(&:name)
-    assert_equal %w[f1 f2 f3 f4], f5.recursive_dependencies.map(&:name)
-    assert_equal %w[f1 f4], f5.runtime_dependencies.map(&:name)
-  end
-
-  def test_runtime_dependencies_with_optional_deps_from_tap
-    tap_loader = mock
-    tap_loader.stubs(:get_formula).raises(RuntimeError, "tried resolving tap formula")
-    Formulary.stubs(:loader_for).with("foo/bar/f1", from: nil).returns(tap_loader)
-
-    stub_formula_loader formula("f2") { url "f2-1.0" }, "baz/qux/f2"
-
-    f3 = formula("f3") do
-      url "f3-1.0"
-      depends_on "foo/bar/f1" => :optional
-      depends_on "baz/qux/f2"
-    end
-
-    # f1 shouldn't be loaded by default.
-    # If it is, an exception will be raised.
-    assert_equal %w[baz/qux/f2], f3.runtime_dependencies.map(&:name)
-
-    # If --with-f1, f1 should be loaded.
-    stub_formula_loader formula("f1") { url "f1-1.0" }, "foo/bar/f1"
-    f3.build = BuildOptions.new(Options.create(%w[--with-f1]), f3.options)
-    assert_equal %w[foo/bar/f1 baz/qux/f2], f3.runtime_dependencies.map(&:name)
-  end
-
-  def test_requirements
-    f1 = formula("f1") do
-      url "f1-1"
-
-      depends_on :python
-      depends_on x11: :recommended
-      depends_on xcode: ["1.0", :optional]
-    end
-    stub_formula_loader f1
-
-    python = PythonRequirement.new
-    x11 = X11Requirement.new("x11", [:recommended])
-    xcode = XcodeRequirement.new(["1.0", :optional])
-
-    # Default block should filter out deps that aren't being used
-    assert_equal Set[python, x11], Set.new(f1.recursive_requirements)
-
-    f1.build = BuildOptions.new(["--with-xcode", "--without-x11"], f1.options)
-    assert_equal Set[python, xcode], Set.new(f1.recursive_requirements)
-    f1.build = f1.stable.build
-
-    f2 = formula("f2") do
-      url "f2-1"
-      depends_on "f1"
-    end
-
-    assert_equal Set[python, x11], Set.new(f2.recursive_requirements)
-
-    # Empty block should allow all requirements
-    assert_equal Set[python, x11, xcode], Set.new(f2.recursive_requirements {})
-
-    # Requirements can be pruned
-    requirements = f2.recursive_requirements do |_dependent, requirement|
-      Requirement.prune if requirement.is_a?(PythonRequirement)
-    end
-    assert_equal Set[x11, xcode], Set.new(requirements)
-  end
-
-  def test_to_hash
-    f1 = formula("foo") do
-      url "foo-1.0"
-    end
-
-    h = f1.to_hash
-    assert h.is_a?(Hash), "Formula#to_hash should return a Hash"
-    assert_equal "foo", h["name"]
-    assert_equal "foo", h["full_name"]
-    assert_equal "1.0", h["versions"]["stable"]
-  end
-
-  def test_to_hash_bottle
-    f1 = formula("foo") do
-      url "foo-1.0"
-
-      bottle do
-        cellar :any
-        sha256 TEST_SHA256 => Utils::Bottles.tag
-      end
-    end
-
-    h = f1.to_hash
-    assert h.is_a?(Hash), "Formula#to_hash should return a Hash"
-    assert h["versions"]["bottle"], "The hash should say the formula is bottled"
-  end
-
-  def test_eligible_kegs_for_cleanup
-    f1 = Class.new(Testball) do
-      version "1.0"
-    end.new
-    f2 = Class.new(Testball) do
-      version "0.2"
-      version_scheme 1
-    end.new
-    f3 = Class.new(Testball) do
-      version "0.3"
-      version_scheme 1
-    end.new
-    f4 = Class.new(Testball) do
-      version "0.1"
-      version_scheme 2
-    end.new
-
-    shutup do
-      [f1, f2, f3, f4].each do |f|
-        f.brew { f.install }
-        Tab.create(f, DevelopmentTools.default_compiler, :libcxx).write
-      end
-    end
-
-    assert_predicate f1, :installed?
-    assert_predicate f2, :installed?
-    assert_predicate f3, :installed?
-    assert_predicate f4, :installed?
-
-    assert_equal [f2, f1].map { |f| Keg.new(f.prefix) },
-                 f3.eligible_kegs_for_cleanup.sort_by(&:version)
-  end
-
-  def test_eligible_kegs_for_cleanup_keg_pinned
-    f1 = Class.new(Testball) { version "0.1" }.new
-    f2 = Class.new(Testball) { version "0.2" }.new
-    f3 = Class.new(Testball) { version "0.3" }.new
-
-    shutup do
-      f1.brew { f1.install }
-      f1.pin
-      f2.brew { f2.install }
-      f3.brew { f3.install }
-    end
-
-    assert_equal (HOMEBREW_PINNED_KEGS/f1.name).resolved_path, f1.prefix
-
-    assert_predicate f1, :installed?
-    assert_predicate f2, :installed?
-    assert_predicate f3, :installed?
-
-    assert_equal [Keg.new(f2.prefix)], shutup { f3.eligible_kegs_for_cleanup }
-  end
-
-  def test_eligible_kegs_for_cleanup_head_installed
-    f = formula do
-      version "0.1"
-      head "foo"
-    end
-
-    stable_prefix = f.installed_prefix
-    stable_prefix.mkpath
-
-    [["000000_1", 1], ["111111", 2], ["111111_1", 2]].each do |pkg_version_suffix, stamp|
-      prefix = f.prefix("HEAD-#{pkg_version_suffix}")
-      prefix.mkpath
-      tab = Tab.empty
-      tab.tabfile = prefix.join("INSTALL_RECEIPT.json")
-      tab.source_modified_time = stamp
-      tab.write
-    end
-
-    eligible_kegs = f.installed_kegs - [Keg.new(f.prefix("HEAD-111111_1"))]
-    assert_equal eligible_kegs, f.eligible_kegs_for_cleanup
-  end
-
-  def test_pour_bottle
-    f_false = formula("foo") do
-      url "foo-1.0"
-      def pour_bottle?
-        false
-      end
-    end
-    refute f_false.pour_bottle?
-
-    f_true = formula("foo") do
-      url "foo-1.0"
-      def pour_bottle?
-        true
-      end
-    end
-    assert f_true.pour_bottle?
-  end
-
-  def test_pour_bottle_dsl
-    f_false = formula("foo") do
-      url "foo-1.0"
-      pour_bottle? do
-        reason "false reason"
-        satisfy { var == etc }
-      end
-    end
-    refute f_false.pour_bottle?
-
-    f_true = formula("foo") do
-      url "foo-1.0"
-      pour_bottle? do
-        reason "true reason"
-        satisfy { true }
-      end
-    end
-    assert f_true.pour_bottle?
-  end
-end
-
-class AliasChangeTests < Homebrew::TestCase
-  attr_reader :f, :new_formula, :tab, :alias_path
-
-  def make_formula(name, version)
-    f = formula(name, alias_path: alias_path) { url "foo-#{version}" }
-    f.build = tab
-    f
-  end
-
-  def setup
-    super
-
-    alias_name = "bar"
-    @alias_path = "#{CoreTap.instance.alias_dir}/#{alias_name}"
-
-    @tab = Tab.empty
-
-    @f = make_formula("formula_name", "1.0")
-    @new_formula = make_formula("new_formula_name", "1.1")
-
-    Formula.stubs(:installed).returns([f])
-  end
-
-  def test_alias_changes_when_not_installed_with_alias
-    tab.source["path"] = Formulary.core_path(f.name).to_s
-
-    assert_nil f.current_installed_alias_target
-    assert_equal f, f.latest_formula
-    refute_predicate f, :installed_alias_target_changed?
-    refute_predicate f, :supersedes_an_installed_formula?
-    refute_predicate f, :alias_changed?
-    assert_predicate f.old_installed_formulae, :empty?
-  end
-
-  def test_alias_changes_when_not_changed
-    tab.source["path"] = alias_path
-    stub_formula_loader(f, alias_path)
-
-    assert_equal f, f.current_installed_alias_target
-    assert_equal f, f.latest_formula
-    refute_predicate f, :installed_alias_target_changed?
-    refute_predicate f, :supersedes_an_installed_formula?
-    refute_predicate f, :alias_changed?
-    assert_predicate f.old_installed_formulae, :empty?
-  end
-
-  def test_alias_changes_when_new_alias_target
-    tab.source["path"] = alias_path
-    stub_formula_loader(new_formula, alias_path)
-
-    assert_equal new_formula, f.current_installed_alias_target
-    assert_equal new_formula, f.latest_formula
-    assert_predicate f, :installed_alias_target_changed?
-    refute_predicate f, :supersedes_an_installed_formula?
-    assert_predicate f, :alias_changed?
-    assert_predicate f.old_installed_formulae, :empty?
-  end
-
-  def test_alias_changes_when_old_formulae_installed
-    tab.source["path"] = alias_path
-    stub_formula_loader(new_formula, alias_path)
-
-    assert_equal new_formula, new_formula.current_installed_alias_target
-    assert_equal new_formula, new_formula.latest_formula
-    refute_predicate new_formula, :installed_alias_target_changed?
-    assert_predicate new_formula, :supersedes_an_installed_formula?
-    assert_predicate new_formula, :alias_changed?
-    assert_equal [f], new_formula.old_installed_formulae
-  end
-end
-
-class OutdatedVersionsTests < Homebrew::TestCase
-  attr_reader :outdated_prefix,
-              :same_prefix,
-              :greater_prefix,
-              :head_prefix,
-              :old_alias_target_prefix
-  attr_reader :f, :old_formula, :new_formula
-
-  def setup
-    super
-
-    @f = formula do
-      url "foo"
-      version "1.20"
-    end
-
-    @old_formula = formula("foo@1") { url "foo-1.0" }
-    @new_formula = formula("foo@2") { url "foo-2.0" }
-
-    @outdated_prefix = HOMEBREW_CELLAR/"#{f.name}/1.11"
-    @same_prefix = HOMEBREW_CELLAR/"#{f.name}/1.20"
-    @greater_prefix = HOMEBREW_CELLAR/"#{f.name}/1.21"
-    @head_prefix = HOMEBREW_CELLAR/"#{f.name}/HEAD"
-    @old_alias_target_prefix = HOMEBREW_CELLAR/"#{old_formula.name}/1.0"
-  end
-
-  def alias_path
-    "#{@f.tap.alias_dir}/bar"
-  end
-
-  def setup_tab_for_prefix(prefix, options = {})
-    prefix.mkpath
-    tab = Tab.empty
-    tab.tabfile = prefix.join("INSTALL_RECEIPT.json")
-    tab.source["path"] = options[:path].to_s if options[:path]
-    tab.source["tap"] = options[:tap] if options[:tap]
-    tab.source["versions"] = options[:versions] if options[:versions]
-    tab.source_modified_time = options[:source_modified_time].to_i
-    tab.write unless options[:no_write]
-    tab
-  end
-
-  def reset_outdated_kegs
-    f.instance_variable_set(:@outdated_kegs, nil)
-  end
-
-  def test_greater_different_tap_installed
-    setup_tab_for_prefix(greater_prefix, tap: "user/repo")
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_greater_same_tap_installed
-    f.instance_variable_set(:@tap, CoreTap.instance)
-    setup_tab_for_prefix(greater_prefix, tap: "homebrew/core")
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_different_tap_installed
-    setup_tab_for_prefix(outdated_prefix, tap: "user/repo")
-    refute_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_same_tap_installed
-    f.instance_variable_set(:@tap, CoreTap.instance)
-    setup_tab_for_prefix(outdated_prefix, tap: "homebrew/core")
-    refute_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_follow_alias_and_alias_unchanged
-    f.follow_installed_alias = true
-    f.build = setup_tab_for_prefix(same_prefix, path: alias_path)
-    stub_formula_loader(f, alias_path)
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_follow_alias_and_alias_changed_and_new_target_not_installed
-    f.follow_installed_alias = true
-    f.build = setup_tab_for_prefix(same_prefix, path: alias_path)
-    stub_formula_loader(new_formula, alias_path)
-    refute_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_follow_alias_and_alias_changed_and_new_target_installed
-    f.follow_installed_alias = true
-    f.build = setup_tab_for_prefix(same_prefix, path: alias_path)
-    stub_formula_loader(new_formula, alias_path)
-    setup_tab_for_prefix(new_formula.prefix) # install new_formula
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_no_follow_alias_and_alias_unchanged
-    f.follow_installed_alias = false
-    f.build = setup_tab_for_prefix(same_prefix, path: alias_path)
-    stub_formula_loader(f, alias_path)
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_no_follow_alias_and_alias_changed
-    f.follow_installed_alias = false
-    f.build = setup_tab_for_prefix(same_prefix, path: alias_path)
-    stub_formula_loader(formula("foo@2") { url "foo-2.0" }, alias_path)
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_old_alias_targets_installed
-    @f = formula(alias_path: alias_path) { url "foo-1.0" }
-    tab = setup_tab_for_prefix(old_alias_target_prefix, path: alias_path)
-    old_formula.build = tab
-    Formula.stubs(:installed).returns([old_formula])
-    refute_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_old_alias_targets_not_installed
-    @f = formula(alias_path: alias_path) { url "foo-1.0" }
-    tab = setup_tab_for_prefix(old_alias_target_prefix, path: old_formula.path)
-    old_formula.build = tab
-    Formula.stubs(:installed).returns([old_formula])
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_same_head_installed
-    f.instance_variable_set(:@tap, CoreTap.instance)
-    setup_tab_for_prefix(head_prefix, tap: "homebrew/core")
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_different_head_installed
-    f.instance_variable_set(:@tap, CoreTap.instance)
-    setup_tab_for_prefix(head_prefix, tap: "user/repo")
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_mixed_taps_greater_version_installed
-    f.instance_variable_set(:@tap, CoreTap.instance)
-    setup_tab_for_prefix(outdated_prefix, tap: "homebrew/core")
-    setup_tab_for_prefix(greater_prefix, tap: "user/repo")
-
-    assert_predicate f.outdated_kegs, :empty?
-
-    setup_tab_for_prefix(greater_prefix, tap: "homebrew/core")
-    reset_outdated_kegs
-
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_mixed_taps_outdated_version_installed
-    f.instance_variable_set(:@tap, CoreTap.instance)
-
-    extra_outdated_prefix = HOMEBREW_CELLAR/"#{f.name}/1.0"
-
-    setup_tab_for_prefix(outdated_prefix)
-    setup_tab_for_prefix(extra_outdated_prefix, tap: "homebrew/core")
-    reset_outdated_kegs
-
-    refute_predicate f.outdated_kegs, :empty?
-
-    setup_tab_for_prefix(outdated_prefix, tap: "user/repo")
-    reset_outdated_kegs
-
-    refute_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_same_version_tap_installed
-    f.instance_variable_set(:@tap, CoreTap.instance)
-    setup_tab_for_prefix(same_prefix, tap: "homebrew/core")
-
-    assert_predicate f.outdated_kegs, :empty?
-
-    setup_tab_for_prefix(same_prefix, tap: "user/repo")
-    reset_outdated_kegs
-
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_installed_head_less_than_stable
-    tab = setup_tab_for_prefix(head_prefix, versions: { "stable" => "1.0" })
-    refute_predicate f.outdated_kegs, :empty?
-
-    # Tab.for_keg(head_prefix) will be fetched from CACHE but we write it anyway
-    tab.source["versions"] = { "stable" => f.version.to_s }
-    tab.write
-    reset_outdated_kegs
-
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_fetch_head
-    outdated_stable_prefix = HOMEBREW_CELLAR.join("testball/1.0")
-    head_prefix_a = HOMEBREW_CELLAR.join("testball/HEAD")
-    head_prefix_b = HOMEBREW_CELLAR.join("testball/HEAD-aaaaaaa_1")
-    head_prefix_c = HOMEBREW_CELLAR.join("testball/HEAD-18a7103")
-
-    setup_tab_for_prefix(outdated_stable_prefix)
-    tab_a = setup_tab_for_prefix(head_prefix_a, versions: { "stable" => "1.0" })
-    setup_tab_for_prefix(head_prefix_b)
-
-    testball_repo = HOMEBREW_PREFIX.join("testball_repo")
-    testball_repo.mkdir
-
-    @f = formula("testball") do
-      url "foo"
-      version "2.10"
-      head "file://#{testball_repo}", using: :git
-    end
-
-    testball_repo.cd do
-      FileUtils.touch "LICENSE"
-      shutup do
-        system "git", "init"
-        system "git", "add", "--all"
-        system "git", "commit", "-m", "Initial commit"
-      end
-    end
-
-    refute_predicate f.outdated_kegs(fetch_head: true), :empty?
-
-    tab_a.source["versions"] = { "stable" => f.version.to_s }
-    tab_a.write
-    reset_outdated_kegs
-    refute_predicate f.outdated_kegs(fetch_head: true), :empty?
-
-    head_prefix_a.rmtree
-    reset_outdated_kegs
-    refute_predicate f.outdated_kegs(fetch_head: true), :empty?
-
-    setup_tab_for_prefix(head_prefix_c, source_modified_time: 1)
-    reset_outdated_kegs
-    assert_predicate f.outdated_kegs(fetch_head: true), :empty?
-  ensure
-    testball_repo.rmtree if testball_repo.exist?
-  end
-
-  def test_outdated_kegs_version_scheme_changed
-    @f = formula("testball") do
-      url "foo"
-      version "20141010"
-      version_scheme 1
-    end
-
-    prefix = HOMEBREW_CELLAR.join("testball/0.1")
-    setup_tab_for_prefix(prefix, versions: { "stable" => "0.1" })
-
-    refute_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_kegs_mixed_version_schemes
-    @f = formula("testball") do
-      url "foo"
-      version "20141010"
-      version_scheme 3
-    end
-
-    prefix_a = HOMEBREW_CELLAR.join("testball/20141009")
-    setup_tab_for_prefix(prefix_a, versions: { "stable" => "20141009", "version_scheme" => 1 })
-
-    prefix_b = HOMEBREW_CELLAR.join("testball/2.14")
-    setup_tab_for_prefix(prefix_b, versions: { "stable" => "2.14", "version_scheme" => 2 })
-
-    refute_predicate f.outdated_kegs, :empty?
-    reset_outdated_kegs
-
-    prefix_c = HOMEBREW_CELLAR.join("testball/20141009")
-    setup_tab_for_prefix(prefix_c, versions: { "stable" => "20141009", "version_scheme" => 3 })
-
-    refute_predicate f.outdated_kegs, :empty?
-    reset_outdated_kegs
-
-    prefix_d = HOMEBREW_CELLAR.join("testball/20141011")
-    setup_tab_for_prefix(prefix_d, versions: { "stable" => "20141009", "version_scheme" => 3 })
-    assert_predicate f.outdated_kegs, :empty?
-  end
-
-  def test_outdated_kegs_head_with_version_scheme
-    @f = formula("testball") do
-      url "foo"
-      version "1.0"
-      version_scheme 2
-    end
-
-    head_prefix = HOMEBREW_CELLAR.join("testball/HEAD")
-
-    setup_tab_for_prefix(head_prefix, versions: { "stable" => "1.0", "version_scheme" => 1 })
-    refute_predicate f.outdated_kegs, :empty?
-
-    reset_outdated_kegs
-    head_prefix.rmtree
-
-    setup_tab_for_prefix(head_prefix, versions: { "stable" => "1.0", "version_scheme" => 2 })
-    assert_predicate f.outdated_kegs, :empty?
-  end
-end
diff --git a/Library/Homebrew/test/formulary_spec.rb b/Library/Homebrew/test/formulary_spec.rb
index 8e9d235896..213ad511d7 100644
--- a/Library/Homebrew/test/formulary_spec.rb
+++ b/Library/Homebrew/test/formulary_spec.rb
@@ -216,4 +216,12 @@ describe Formulary do
       end
     end
   end
+
+  describe "::core_path" do
+    it "returns the path to a Formula in the core tap" do
+      name = "foo-bar"
+      expect(subject.core_path(name))
+        .to eq(Pathname.new("#{HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core/Formula/#{name}.rb"))
+    end
+  end
 end