Adding tests for dependency_collector on Linux

Library/Homebrew/test/dependency_collector_spec.rb

@@ -140,3 +140,4 @@ describe DependencyCollector do
     end
   end
 end
+require "test/os/dependency_collector_spec"

Library/Homebrew/test/os/dependency_collector_spec.rb

@@ -0,0 +1 @@
+require "test/os/linux/dependency_collector_spec" if OS.linux?

Library/Homebrew/test/os/linux/dependency_collector_spec.rb

@@ -0,0 +1,23 @@
+require "dependency_collector"
+
+describe DependencyCollector do
+  alias_matcher :be_a_build_requirement, :be_build
+
+  after(:each) do
+    described_class.clear_cache
+  end
+
+  describe "#add" do
+    it "creates a resource dependency from a '.zip' URL" do
+      resource = Resource.new
+      resource.url("http://example.com/foo.zip")
+      expect(subject.add(resource)).to eq(Dependency.new("zip", [:build]))
+    end
+
+    it "creates a resource dependency from a '.bzip2' URL" do
+      resource = Resource.new
+      resource.url("http://example.com/foo.tar.bzip2")
+      expect(subject.add(resource)).to eq(Dependency.new("bzip2", [:build]))
+    end
+  end
+end