add new spec to cmd/fetch_spec

Library/Homebrew/test/cmd/fetch_spec.rb

@@ -4,6 +4,10 @@
 require "cmd/shared_examples/args_parse"
 
 describe "brew fetch" do
+  let(:local_transmission) do
+    Cask::CaskLoader.load(cask_path("local-transmission"))
+  end
+
   it_behaves_like "parseable arguments"
 
   it "downloads the Formula's URL", :integration_test do
@@ -14,4 +18,27 @@ describe "brew fetch" do
     expect(HOMEBREW_CACHE/"testball--0.1.tbz").to be_a_symlink
     expect(HOMEBREW_CACHE/"testball--0.1.tbz").to exist
   end
+
+  it "prevents double fetch (without nuking existing installation)", :integration_test, :needs_macos do
+    cached_location = Cask::Download.new(local_transmission).fetch
+
+    old_ctime = File.stat(cached_location).ctime
+
+    expect { brew "fetch", "local-transmission", "--cask", "--no-quarantine" }.to be_a_success
+    new_ctime = File.stat(cached_location).ctime
+
+    expect(old_ctime.to_i).to eq(new_ctime.to_i)
+  end
+
+  it "allows double fetch with --force", :integration_test, :needs_macos do
+    cached_location = Cask::Download.new(local_transmission).fetch
+
+    old_ctime = File.stat(cached_location).ctime
+    sleep(1)
+
+    expect { brew "fetch", "local-transmission", "--cask", "--force", "--no-quarantine" }.to be_a_success
+    new_ctime = File.stat(cached_location).ctime
+
+    expect(new_ctime.to_i).to be > old_ctime.to_i
+  end
 end