Engine: cleanup side effects between tests

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)

engine/engine.go

@@ -29,6 +29,10 @@ func Register(name string, handler Handler) error {
 	return nil
 }
 
+func unregister(name string) {
+	delete(globalHandlers, name)
+}
+
 // The Engine is the core of Docker.
 // It acts as a store for *containers*, and allows manipulation of these
 // containers by executing *jobs*.

engine/engine_test.go

@@ -16,6 +16,8 @@ func TestRegister(t *testing.T) {
 	if err := Register("dummy1", nil); err == nil {
 		t.Fatalf("Expecting error, got none")
 	}
+	// Register is global so let's cleanup to avoid conflicts
+	defer unregister("dummy1")
 
 	eng := newTestEngine(t)
 
@@ -32,6 +34,7 @@ func TestRegister(t *testing.T) {
 	if err := eng.Register("dummy2", nil); err == nil {
 		t.Fatalf("Expecting error, got none")
 	}
+	defer unregister("dummy2")
 }
 
 func TestJob(t *testing.T) {
@@ -48,6 +51,7 @@ func TestJob(t *testing.T) {
 	}
 
 	eng.Register("dummy2", h)
+	defer unregister("dummy2")
 	job2 := eng.Job("dummy2", "--level=awesome")
 
 	if job2.handler == nil {