brew/Library/Homebrew/test/cmd/desc_spec.rb

describe "brew desc", :integration_test do
  let(:desc_cache) { HOMEBREW_CACHE/"desc_cache.json" }

  it "shows a given Formula's description" do
    setup_test_formula "testball"

    expect { brew "desc", "testball" }
      .to output("testball: Some test\n").to_stdout
      .and not_to_output.to_stderr
      .and be_a_success
  end

  describe "--description" do
    it "creates a description cache" do
      expect(desc_cache).not_to exist

      expect { brew "desc", "--description", "testball" }.to be_a_success

      expect(desc_cache).to exist
    end
  end
end