I am not convinced that you need this change. In particular, I don't think utils/gomega_helpers.go is maintainable in the long run, as gomega has so many assert functions. Are we going to keep wrapping them, as we introduce new ones? I think the wrappers are making things more complex.

E.g., if I see:

gomega.Expect(err).Should(gomega.BeNil(), fmt.Sprintf("failed to inject: %s", stderr)

I can look up the godoc to see what it does.

With this change:

utils.ExpectNil(err, "`linkerd inject` command failed: %s\n%s", out, stderr)

Now I also need to look up what utils.ExpectNil() does (e.g. what are out and stderr used for).

The simplest is still just if err == nil 😄.

It feels like we picked a test framework, now we are trying to work around it (specifically, its verbosity), instead of with it.