Function contains

internal/app/done_test.go:280–287

contains is a tiny strings.Contains shim so done_test.go doesn't need a strings import just for this.

(haystack, needle string)

// contains is a tiny strings.Contains shim so done_test.go doesn't need
// a strings import just for this.
func contains(haystack, needle string) bool {
	for i := 0; i+len(needle) <= len(haystack); i++ {
		if haystack[i:i+len(needle)] == needle {
			return true
		}
	}
	return false
}