Add integration tests for autoremove cmd

Library/Homebrew/test/cmd/autoremove_spec.rb

@@ -5,4 +5,34 @@ require "cmd/shared_examples/args_parse"
 
 describe "brew autoremove" do
   it_behaves_like "parseable arguments"
+
+  describe "integration test" do
+    let(:requested_formula) { Formula["testball1"] }
+    let(:unused_formula) { Formula["testball2"] }
+
+    before do
+      install_test_formula "testball1"
+      install_test_formula "testball2"
+
+      # Make testball2 an unused dependency
+      tab = Tab.for_name("testball2")
+      tab.installed_on_request = false
+      tab.installed_as_dependency = true
+      tab.write
+    end
+
+    it "only removes unused dependencies", :integration_test do
+      expect(requested_formula.any_version_installed?).to be true
+      expect(unused_formula.any_version_installed?).to be true
+
+      # When there are unused dependencies
+      expect { brew "autoremove" }
+        .to be_a_success
+        .and output(/Autoremoving/).to_stdout
+        .and not_to_output.to_stderr
+
+      expect(requested_formula.any_version_installed?).to be true
+      expect(unused_formula.any_version_installed?).to be false
+    end
+  end
 end