Add streaming Test

[Lily922]

Add unit test to streaming part.

[k8s-reviewable]

This change is 

[resouer]

@LilyFaFa Awesome work! btw, you can install coverage tool for golang to measure your work.

go get golang.org/x/tools/cmd/cover
go test -coverprofile <filename> <package name>

Then you can measure your work for even single file.

[resouer]

/lgtm