Function TestFetchDERPMapMemoryCache

tailcat_test.go:428–448

TestFetchDERPMapMemoryCache verifies the default in-memory DERP map cache: a second fetch of the same URL within the freshness window makes no network request.

(t *testing.T)

// cache: a second fetch of the same URL within the freshness window
// makes no network request.
func TestFetchDERPMapMemoryCache(t *testing.T) {
	var fetches atomic.Int32
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fetches.Add(1)
		fmt.Fprint(w, `{"Regions":{"1":{"RegionID":1}}}`)
	}))
	defer srv.Close()

	for range 2 {
		dm, err := FetchDERPMap(context.Background(), DERPMapURL(srv.URL))
		if err != nil {
			t.Fatal(err)
		}
		if len(dm.Regions) != 1 {
			t.Fatalf("got %d regions; want 1", len(dm.Regions))
		}
	}
	if n := fetches.Load(); n != 1 {
		t.Errorf("fetches = %d; want 1", n)
	}
}