type tb struct {
	name            string
	mu              sync.Mutex
	output          []string
	skipped, failed bool
	// The testing.TB interface has an unexported method "to prevent users implementing the
	// interface and so future additions to it will not violate Go 1 compatibility."
	//
	// This may cause problems across Go versions, but let's ignore them and
	// work around that restriction by embedding a T so we satisfy the unexported methods of the interface.
	*testing.T
}

var _ testing.TB = (*tb)(nil)

func (t *tb) Error(args ...interface{}) {
	t.Log(args...)
	t.Fail()
}
func (t *tb) Errorf(format string, args ...interface{}) {
	t.Logf(format, args...)
	t.Fail()
}
func (t *tb) Fail() {
	t.mu.Lock()
	t.failed = true
	t.mu.Unlock()
}
func (t *tb) FailNow() {
	t.Fail()
	runtime.Goexit()
}
func (t *tb) Failed() bool {
	t.mu.Lock()
	failed := t.failed
	t.mu.Unlock()
	return failed
}
func (t *tb) Fatal(args ...interface{}) {
	t.Log(args...)
	t.FailNow()
}
func (t *tb) Fatalf(format string, args ...interface{}) {
	t.Logf(format, args...)
	t.FailNow()
}
func (t *tb) Log(args ...interface{}) {
	t.mu.Lock()
	defer t.mu.Unlock()
	t.output = append(t.output, fmt.Sprintln(args...))
}
func (t *tb) Logf(format string, args ...interface{}) {
	t.mu.Lock()
	defer t.mu.Unlock()
	// Ensure message ends with newline.
	if len(format) > 0 && format[len(format)-1] != '\n' {
		format += "\n"
	}
	t.output = append(t.output, fmt.Sprintf(format, args...))
}
func (t *tb) Name() string {
	return t.name
}
func (t *tb) Skip(args ...interface{}) {
	t.Log(args...)
	t.SkipNow()
}
func (t *tb) SkipNow() {
	t.mu.Lock()
	t.skipped = true
	t.mu.Unlock()
	runtime.Goexit()
}
func (t *tb) Skipf(format string, args ...interface{}) {
	t.Logf(format, args...)
	t.SkipNow()
}
func (t *tb) Skipped() bool {
	t.mu.Lock()
	skipped := t.skipped
	t.mu.Unlock()
	return skipped
}
func (t *tb) Helper() {}