Add test for `uninstall` before removing artifacts.

Library/Homebrew/cask/spec/cask/cli/uninstall_spec.rb

@@ -41,6 +41,25 @@ describe Hbc::CLI::Uninstall do
     expect(Hbc.appdir.join("Caffeine.app")).not_to exist
   end
 
+  it "calls `uninstall` before removing artifacts" do
+    cask = Hbc::CaskLoader.load_from_file(TEST_FIXTURE_DIR/"cask/Casks/with-uninstall-script-app.rb")
+
+    shutup do
+      Hbc::Installer.new(cask).install
+    end
+
+    expect(cask).to be_installed
+
+    expect {
+      shutup do
+        Hbc::CLI::Uninstall.run("with-uninstall-script-app")
+      end
+    }.not_to raise_error
+
+    expect(cask).not_to be_installed
+    expect(Hbc.appdir.join("MyFancyApp.app")).not_to exist
+  end
+
   describe "when multiple versions of a cask are installed" do
     let(:token) { "versioned-cask" }
     let(:first_installed_version) { "1.2.3" }

Library/Homebrew/test/support/fixtures/cask/Casks/with-uninstall-script-app.rb

+cask 'with-uninstall-script-app' do
+  version '1.2.3'
+  sha256 '5633c3a0f2e572cbf021507dec78c50998b398c343232bdfc7e26221d0a5db4d'
+
+  url "file://#{TEST_FIXTURE_DIR}/cask/MyFancyApp.zip"
+  homepage 'http://example.com/MyFancyApp'
+
+  app 'MyFancyApp/MyFancyApp.app'
+
+  postflight do
+    IO.write "#{appdir}/MyFancyApp.app/uninstall.sh", <<-EOS.undent
+      #!/bin/sh
+      /bin/rm -r "#{appdir}/MyFancyApp.app"
+    EOS
+  end
+
+  uninstall script: {
+                      executable: "#{appdir}/MyFancyApp.app/uninstall.sh",
+                      sudo: false
+                    }
+end