Function TestSingleflightWithError

registry/cache/cache_test.go:133–175

TestSingleflightWithError verifies that when etcd fails, only one request is made and all concurrent callers receive the error

(t *testing.T)

// TestSingleflightWithError verifies that when etcd fails, only one request is made
// and all concurrent callers receive the error
func TestSingleflightWithError(t *testing.T) {
	expectedErr := errors.New("etcd connection failed")
	mock := &mockRegistry{
		delay: 50 * time.Millisecond,
		err:   expectedErr,
	}

	// Type assertion to *cache is necessary to access internal state for verification
	c := New(mock, func(o *Options) {
		o.TTL = time.Minute
		o.Logger = logger.DefaultLogger
	}).(*cache)

	// Launch concurrent requests
	const concurrency = 10
	var wg sync.WaitGroup
	wg.Add(concurrency)

	errs := make([]error, concurrency)

	for i := 0; i < concurrency; i++ {
		go func(idx int) {
			defer wg.Done()
			_, err := c.GetService("test.service")
			errs[idx] = err
		}(i)
	}

	wg.Wait()

	// Verify that only 1 call was made to the underlying registry
	callCount := mock.getCallCount()
	if callCount != 1 {
		t.Errorf("Expected 1 call to registry even on error, got %d", callCount)
	}

	// Verify all requests got the error
	for i := 0; i < concurrency; i++ {
		if errs[i] == nil {
			t.Errorf("Request %d should have failed", i)
		}
	}
}

// TestStaleCacheOnError verifies that stale cache is returned when registry fails
func TestStaleCacheOnError(t *testing.T) {