When running the following assertion,

Expect(t, fmt.Errorf("some error")).To(Not(HaveOccurred()))

we get the output below

$ go test
--- FAIL: TestSomething (0.00s)
	expect.go:44: match matchers.HaveOccurredMatcher{}
		/Users/wfernandes/workspace/go/src/test/some_test.go:14

match matchers.HaveOccurredMatcher{} is not as useful when it comes to understanding what originally failed. It would be nice to see the failure from the HaveOccurred matcher.