Forget a runtime's old instance once it answers under a new one, so a restart is not reported as a missed answer

node-tools/internal/console/runtimes_test.go

@@ -198,3 +198,22 @@ func TestARuntimeHeardBeforeAndNotNowIsNamed(t *testing.T) {
 		t.Errorf("%v", err)
 	}
 }
+
+// A runtime restarted answers under a new instance id; its old instance is gone, not unheard.
+func TestARestartedRuntimeIsNotNamedUnheard(t *testing.T) {
+	heard := func(id string) *index {
+		return &index{Modules: map[string]*moduleInfo{}, Recorded: map[string][]string{}, Discovery: announce.Discovery{At: time.Now().UTC(),
+			Heard: []announce.Heard{{Info: micro.Info{ServiceIdentity: micro.ServiceIdentity{Name: "node-tools", ID: id,
+				Metadata: map[string]string{"node": "laptop"}}}}}}}
+	}
+	s := &Surface{}
+	s.remember(heard("before-restart"))
+	after := heard("after-restart")
+	s.remember(after)
+	if len(after.Unheard) != 0 {
+		t.Errorf("a restarted runtime was named unheard: %+v", after.Unheard)
+	}
+	if len(s.runtimes) != 1 {
+		t.Errorf("the old instance is still kept: %d runtimes", len(s.runtimes))
+	}
+}