fixed tests

[frairon]

No description provided.

[mmreza79]

One question. Is there any difference between Emit and EmitWithHeaders in this PR because you didn't pass any header info.

[frairon]

For this test there is no difference, but the underlying context-implementation changed. A producer has the methods Emit and EmitWithHeaders, those are used when e.g. you call ctx.Emit(..), because the producer-method is passed to the callback-context here: https://github.com/lovoo/goka/blob/master/partition_processor.go#L497
So whatever is passed there, will be called (whether headers are used or not).
And since this commit, EmitWithHeaders is always used, so the mock has to expect that too or the tests will fail.