matchers.go
func ContainSubstring(substr string, args ...interface{}) types.GomegaMatcher {
	return &matchers.ContainSubstringMatcher{
		Substr: substr,
		Args:   args,
	}
}
func ContainSubstring(substr string, args ...interface{}) types.GomegaMatcher {
	return &matchers.ContainSubstringMatcher{
		Substr: substr,
		Args:   args,
	}
}
//ContainSubstring succeeds if actual is a string or stringer that contains the
//passed-in substring.  Optional arguments can be provided to construct the substring
//via fmt.Sprintf().