Simplify and fix unstable test

sd/internal/instance/cache_test.go

@@ -12,50 +12,33 @@ var _ sd.Instancer = &Cache{} // API check
 
 // The test verifies the following:
 // registering causes initial notification of the current state
-// notifications delivered to two receivers
-// identical notifications cause no updates
-// different update causes new notification
 // instances are sorted
+// different update causes new notification
+// identical notifications cause no updates
 // no updates after de-registering
 func TestCache(t *testing.T) {
  e1 := sd.Event{Instances: []string{"y", "x"}} // not sorted
  e2 := sd.Event{Instances: []string{"c", "a", "b"}}
 
- c := NewCache()
- if want, have := 0, len(c.State().Instances); want != have {
+ cache := NewCache()
+ if want, have := 0, len(cache.State().Instances); want != have {
  t.Fatalf("want %v instances, have %v", want, have)
  }
 
- c.Update(e1) // sets initial state
- if want, have := 2, len(c.State().Instances); want != have {
+ cache.Update(e1) // sets initial state
+ if want, have := 2, len(cache.State().Instances); want != have {
  t.Fatalf("want %v instances, have %v", want, have)
  }
 
  r1 := make(chan sd.Event)
- go c.Register(r1)
+ go cache.Register(r1)
  expectUpdate(t, r1, []string{"x", "y"})
 
- r2 := make(chan sd.Event)
- go c.Register(r2)
- expectUpdate(t, r2, []string{"x", "y"})
-
- // send the same instances but in different order.
- // because it's a duplicate it should not cause new notification.
- // if it did, this call would deadlock trying to send to channels with no readers
- c.Update(sd.Event{Instances: []string{"x", "y"}})
- expectNoUpdate(t, r1)
- expectNoUpdate(t, r2)
-
- go c.Update(e2) // different set
+ go cache.Update(e2) // different set
  expectUpdate(t, r1, []string{"a", "b", "c"})
- expectUpdate(t, r2, []string{"a", "b", "c"})
 
- c.Deregister(r1)
- c.Deregister(r2)
+ cache.Deregister(r1)
  close(r1)
- close(r2)
- // if deregister didn't work, Update would panic on closed channels
- c.Update(e1)
 }
 
 func expectUpdate(t *testing.T, r chan sd.Event, expect []string) {
@@ -65,15 +48,30 @@ func expectUpdate(t *testing.T, r chan sd.Event, expect []string) {
  t.Fatalf("want: %v, have: %v", want, have)
  }
  case <-time.After(time.Second):
- t.Fatalf("did not receive expected update")
+ t.Fatalf("did not receive expected update %v", expect)
  }
 }
 
-func expectNoUpdate(t *testing.T, r chan sd.Event) {
- select {
- case e := <-r:
- t.Errorf("received unexpected update %v", e)
- case <-time.After(time.Millisecond):
- return // as expected
+func TestRegistry(t *testing.T) {
+ reg := make(registry)
+ c1 := make(chan sd.Event, 1)
+ c2 := make(chan sd.Event, 1)
+ reg.register(c1)
+ reg.register(c2)
+
+ // validate that both channels receive the update
+ reg.broadcast(sd.Event{Instances: []string{"x", "y"}})
+ if want, have := []string{"x", "y"}, (<-c1).Instances; !reflect.DeepEqual(want, have) {
+ t.Fatalf("want: %v, have: %v", want, have)
  }
+ if want, have := []string{"x", "y"}, (<-c2).Instances; !reflect.DeepEqual(want, have) {
+ t.Fatalf("want: %v, have: %v", want, have)
+ }
+
+ reg.deregister(c1)
+ reg.deregister(c2)
+ close(c1)
+ close(c2)
+ // if deregister didn't work, broadcast would panic on closed channels
+ reg.broadcast(sd.Event{Instances: []string{"x", "y"}})
 }