Gomock not returning the expected value-CodePudding

I'm an experienced programmer but new to Go. I'm writing some logging tests, and for these purposes I've generated a mock of the LogSink class (using mockgen). Since that part is all auto-generated, I think we can assume nothing untoward there.

So here is my test code:

func TestLogging(t *testing.T) {
    ls := mock.NewMockLogSink(gomock.NewController(t))
    ls.EXPECT().Init(gomock.Any())
    const logLevel = 1
    ls.EXPECT().Enabled(gomock.Any()).AnyTimes().Do(func(level int) bool {
        return level <= logLevel
    })
    log.Set(logr.New(ls))
    ls.EXPECT().Info(gomock.Any(), "Foo").Times(1)
    log.Info("Foo")
    ls.EXPECT().Info(gomock.Any(), "Bar").Times(0)
    log.V(2).Info("Bar")
}

But this test fails, because the "Foo" log never gets called. I stepped through the code and found that my EXPECT().Do() code is being called as expected, and is returning true, but inside the mock code, it sees the result of Logger.sink.Enabled() as false!

What am I doing wrong? Is there a secret switch I'm missing?

CodePudding user response：

Well, it turns out .Do() intentionally ignores return values. Here's the documentation from the code:

// Do declares the action to run when the call is matched. The function's
// return values are ignored to retain backward compatibility. To use the
// return values call DoAndReturn.

Backward compatibility. Right. Bloody pit in the public domain, if you ask me...