Function TestCacheUnchanged

net/dnsfallback/dnsfallback_test.go:107–177

(t *testing.T)

}

func TestCacheUnchanged(t *testing.T) {
	cacheFile := filepath.Join(t.TempDir(), "cache.json")

	// Write initial cache value
	initialCache := &tailcfg.DERPMap{
		Regions: map[int]*tailcfg.DERPRegion{
			99: {
				RegionID:   99,
				RegionCode: "test",
				RegionName: "Testville",
				Nodes: []*tailcfg.DERPNode{{
					Name:     "99a",
					RegionID: 99,
					HostName: "derp99a.tailscale.com",
					IPv4:     "1.2.3.4",
				}},
			},
		},
	}
	d, err := json.Marshal(initialCache)
	if err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(cacheFile, d, 0666); err != nil {
		t.Fatal(err)
	}

	// Clear any existing cached DERP map(s)
	cachedDERPMap.Store(nil)

	// Load the cache
	SetCachePath(cacheFile, t.Logf)
	if cm := cachedDERPMap.Load(); !reflect.DeepEqual(initialCache, cm) {
		t.Fatalf("cached map was %+v; want %+v", cm, initialCache)
	}

	// Remove the cache file on-disk, then re-set to the current value. If
	// our equality comparison is working, we won't rewrite the file
	// on-disk since the cached value won't have changed.
	if err := os.Remove(cacheFile); err != nil {
		t.Fatal(err)
	}

	UpdateCache(initialCache, t.Logf)
	if _, err := os.Stat(cacheFile); !os.IsNotExist(err) {
		t.Fatalf("got err=%v; expected to not find cache file", err)
	}

	// Now, update the cache with something slightly different and verify
	// that we did re-write the file on-disk.
	updatedCache := &tailcfg.DERPMap{
		Regions: map[int]*tailcfg.DERPRegion{
			99: {
				RegionID:   99,
				RegionCode: "test",
				RegionName: "Testville",
				Nodes:      []*tailcfg.DERPNode{ /* set below */ },
			},