Add tests

Library/Homebrew/test/global_spec.rb

@@ -8,4 +8,14 @@ describe "brew", :integration_test do
       .and not_to_output.to_stderr
       .and be_a_success
   end
+
+  it "does not require i18n" do
+    # This is a transitive dependency of activesupport, but we don't use it.
+    expect { I18n }.to raise_error(NameError)
+  end
+
+  it "does not require ActiveSupport::Inflector" do
+    # ActiveSupport inflections are slow to load, so we don't use them.
+    expect { ActiveSupport::Inflector }.to raise_error(NameError)
+  end
 end