diff --git a/Library/Homebrew/test/patch_spec.rb b/Library/Homebrew/test/patch_spec.rb
new file mode 100644
index 0000000000..22c1036627
--- /dev/null
+++ b/Library/Homebrew/test/patch_spec.rb
@@ -0,0 +1,165 @@
+require "patch"
+
+describe Patch do
+  describe "#create" do
+    context "simple patch" do
+      subject { described_class.create(:p2, nil) }
+      it { is_expected.to be_kind_of ExternalPatch }
+      it { is_expected.to be_external }
+      its(:strip) { is_expected.to eq(:p2) }
+    end
+
+    context "string patch" do
+      subject { described_class.create(:p0, "foo") }
+      it { is_expected.to be_kind_of StringPatch }
+      its(:strip) { is_expected.to eq(:p0) }
+    end
+
+    context "string patch without strip" do
+      subject { described_class.create("foo", nil) }
+      it { is_expected.to be_kind_of StringPatch }
+      its(:strip) { is_expected.to eq(:p1) }
+    end
+
+    context "data patch" do
+      subject { described_class.create(:p0, :DATA) }
+      it { is_expected.to be_kind_of DATAPatch }
+      its(:strip) { is_expected.to eq(:p0) }
+    end
+
+    context "data patch without strip" do
+      subject { described_class.create(:DATA, nil) }
+      it { is_expected.to be_kind_of DATAPatch }
+      its(:strip) { is_expected.to eq(:p1) }
+    end
+
+    it "raises an error for unknown values" do
+      expect {
+        described_class.create(Object.new)
+      }.to raise_error(ArgumentError)
+
+      expect {
+        described_class.create(Object.new, Object.new)
+      }.to raise_error(ArgumentError)
+    end
+  end
+
+  describe "#patch_files" do
+    subject { described_class.create(:p2, nil) }
+
+    context "empty patch" do
+      its(:resource) { is_expected.to be_kind_of Resource::Patch }
+      its(:patch_files) { is_expected.to eq(subject.resource.patch_files) }
+      its(:patch_files) { is_expected.to eq([]) }
+    end
+
+    it "returns applied patch files" do
+      subject.resource.apply("patch1.diff")
+      expect(subject.patch_files).to eq(["patch1.diff"])
+
+      subject.resource.apply("patch2.diff", "patch3.diff")
+      expect(subject.patch_files).to eq(["patch1.diff", "patch2.diff", "patch3.diff"])
+
+      subject.resource.apply(["patch4.diff", "patch5.diff"])
+      expect(subject.patch_files.count).to eq(5)
+
+      subject.resource.apply("patch4.diff", ["patch5.diff", "patch6.diff"], "patch7.diff")
+      expect(subject.patch_files.count).to eq(7)
+    end
+  end
+
+  describe "#normalize_legacy_patches" do
+    it "can create a patch from a single string" do
+      patches = described_class.normalize_legacy_patches("http://example.com/patch.diff")
+      expect(patches.length).to eq(1)
+      expect(patches.first.strip).to eq(:p1)
+    end
+
+    it "can create patches from an array" do
+      patches = described_class.normalize_legacy_patches(
+        %w[http://example.com/patch1.diff http://example.com/patch2.diff],
+      )
+
+      expect(patches.length).to eq(2)
+      expect(patches[0].strip).to eq(:p1)
+      expect(patches[1].strip).to eq(:p1)
+    end
+
+    it "can create patches from a :p0 hash" do
+      patches = Patch.normalize_legacy_patches(
+        p0: "http://example.com/patch.diff",
+      )
+
+      expect(patches.length).to eq(1)
+      expect(patches.first.strip).to eq(:p0)
+    end
+
+    it "can create patches from a :p1 hash" do
+      patches = Patch.normalize_legacy_patches(
+        p1: "http://example.com/patch.diff",
+      )
+
+      expect(patches.length).to eq(1)
+      expect(patches.first.strip).to eq(:p1)
+    end
+
+    it "can create patches from a mixed hash" do
+      patches = Patch.normalize_legacy_patches(
+        p1: "http://example.com/patch1.diff",
+        p0: "http://example.com/patch0.diff",
+      )
+
+      expect(patches.length).to eq(2)
+      expect(patches.count { |p| p.strip == :p0 }).to eq(1)
+      expect(patches.count { |p| p.strip == :p1 }).to eq(1)
+    end
+
+    it "can create patches from a mixed hash with array" do
+      patches = Patch.normalize_legacy_patches(
+        p1: [
+          "http://example.com/patch10.diff",
+          "http://example.com/patch11.diff",
+        ],
+        p0: [
+          "http://example.com/patch00.diff",
+          "http://example.com/patch01.diff",
+        ],
+      )
+
+      expect(patches.length).to eq(4)
+      expect(patches.count { |p| p.strip == :p0 }).to eq(2)
+      expect(patches.count { |p| p.strip == :p1 }).to eq(2)
+    end
+
+    it "returns an empty array if given nil" do
+      expect(Patch.normalize_legacy_patches(nil)).to be_empty
+    end
+  end
+end
+
+describe EmbeddedPatch do
+  describe "#new" do
+    subject { described_class.new(:p1) }
+    its(:inspect) { is_expected.to eq("#<EmbeddedPatch: :p1>") }
+  end
+end
+
+describe ExternalPatch do
+  subject { described_class.new(:p1) { url "file:///my.patch" } }
+
+  describe "#url" do
+    its(:url) { is_expected.to eq("file:///my.patch") }
+  end
+
+  describe "#inspect" do
+    its(:inspect) { is_expected.to eq('#<ExternalPatch: :p1 "file:///my.patch">') }
+  end
+
+  describe "#cached_download" do
+    before(:each) do
+      allow(subject.resource).to receive(:cached_download).and_return("/tmp/foo.tar.gz")
+    end
+
+    its(:cached_download) { is_expected.to eq("/tmp/foo.tar.gz") }
+  end
+end
diff --git a/Library/Homebrew/test/patch_test.rb b/Library/Homebrew/test/patch_test.rb
deleted file mode 100644
index 3055eaf48d..0000000000
--- a/Library/Homebrew/test/patch_test.rb
+++ /dev/null
@@ -1,155 +0,0 @@
-require "testing_env"
-require "patch"
-
-class PatchTests < Homebrew::TestCase
-  def test_create_simple
-    patch = Patch.create(:p2, nil)
-    assert_kind_of ExternalPatch, patch
-    assert_predicate patch, :external?
-    assert_equal :p2, patch.strip
-  end
-
-  def test_create_string
-    patch = Patch.create(:p0, "foo")
-    assert_kind_of StringPatch, patch
-    assert_equal :p0, patch.strip
-  end
-
-  def test_create_string_without_strip
-    patch = Patch.create("foo", nil)
-    assert_kind_of StringPatch, patch
-    assert_equal :p1, patch.strip
-  end
-
-  def test_create_data
-    patch = Patch.create(:p0, :DATA)
-    assert_kind_of DATAPatch, patch
-    assert_equal :p0, patch.strip
-  end
-
-  def test_create_data_without_strip
-    patch = Patch.create(:DATA, nil)
-    assert_kind_of DATAPatch, patch
-    assert_equal :p1, patch.strip
-  end
-
-  def test_raises_for_unknown_values
-    assert_raises(ArgumentError) { Patch.create(Object.new) }
-    assert_raises(ArgumentError) { Patch.create(Object.new, Object.new) }
-  end
-end
-
-class LegacyPatchTests < Homebrew::TestCase
-  def test_patch_single_string
-    patches = Patch.normalize_legacy_patches("http://example.com/patch.diff")
-    assert_equal 1, patches.length
-    assert_equal :p1, patches.first.strip
-  end
-
-  def test_patch_array
-    patches = Patch.normalize_legacy_patches(
-      %w[http://example.com/patch1.diff http://example.com/patch2.diff],
-    )
-
-    assert_equal 2, patches.length
-    assert_equal :p1, patches[0].strip
-    assert_equal :p1, patches[1].strip
-  end
-
-  def test_p0_hash_to_string
-    patches = Patch.normalize_legacy_patches(
-      p0: "http://example.com/patch.diff",
-    )
-
-    assert_equal 1, patches.length
-    assert_equal :p0, patches.first.strip
-  end
-
-  def test_p1_hash_to_string
-    patches = Patch.normalize_legacy_patches(
-      p1: "http://example.com/patch.diff",
-    )
-
-    assert_equal 1, patches.length
-    assert_equal :p1, patches.first.strip
-  end
-
-  def test_mixed_hash_to_strings
-    patches = Patch.normalize_legacy_patches(
-      p1: "http://example.com/patch1.diff",
-      p0: "http://example.com/patch0.diff",
-    )
-    assert_equal 2, patches.length
-    assert_equal 1, patches.count { |p| p.strip == :p0 }
-    assert_equal 1, patches.count { |p| p.strip == :p1 }
-  end
-
-  def test_mixed_hash_to_arrays
-    patches = Patch.normalize_legacy_patches(
-      p1: ["http://example.com/patch10.diff",
-           "http://example.com/patch11.diff"],
-      p0: ["http://example.com/patch00.diff",
-           "http://example.com/patch01.diff"],
-    )
-
-    assert_equal 4, patches.length
-    assert_equal 2, patches.count { |p| p.strip == :p0 }
-    assert_equal 2, patches.count { |p| p.strip == :p1 }
-  end
-
-  def test_nil
-    assert_empty Patch.normalize_legacy_patches(nil)
-  end
-end
-
-class EmbeddedPatchTests < Homebrew::TestCase
-  def test_inspect
-    p = EmbeddedPatch.new :p1
-    assert_equal "#<EmbeddedPatch: :p1>", p.inspect
-  end
-end
-
-class ExternalPatchTests < Homebrew::TestCase
-  def setup
-    super
-    @p = ExternalPatch.new(:p1) { url "file:///my.patch" }
-  end
-
-  def test_url
-    assert_equal "file:///my.patch", @p.url
-  end
-
-  def test_inspect
-    assert_equal '#<ExternalPatch: :p1 "file:///my.patch">', @p.inspect
-  end
-
-  def test_cached_download
-    @p.resource.stubs(:cached_download).returns "/tmp/foo.tar.gz"
-    assert_equal "/tmp/foo.tar.gz", @p.cached_download
-  end
-end
-
-class ApplyPatchTests < Homebrew::TestCase
-  def test_empty_patch_files
-    patch = Patch.create(:p2, nil)
-    resource = patch.resource
-    patch_files = patch.patch_files
-    assert_kind_of Resource::Patch, resource
-    assert_equal patch_files, resource.patch_files
-    assert_equal patch_files, []
-  end
-
-  def test_resource_patch_apply_method
-    patch = Patch.create(:p2, nil)
-    resource = patch.resource
-    patch_files = patch.patch_files
-    resource.apply("patch1.diff")
-    assert_equal patch_files, ["patch1.diff"]
-    resource.apply("patch2.diff", "patch3.diff")
-    assert_equal patch_files, ["patch1.diff", "patch2.diff", "patch3.diff"]
-    resource.apply(["patch4.diff", "patch5.diff"])
-    assert_equal patch_files.count, 5
-    resource.apply("patch4.diff", ["patch5.diff", "patch6.diff"], "patch7.diff")
-    assert_equal patch_files.count, 7
-  end
-end