chore: add tests for event.Bus

Small tests to make sure code works as expected.

Signed-off-by: Andrey Smirnov <smirnov.andrey@gmail.com>

internal/app/machined/internal/event/event_test.go

@@ -0,0 +1,58 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package event_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+
+	"github.com/talos-systems/talos/internal/app/machined/internal/event"
+)
+
+type EventSuite struct {
+	suite.Suite
+}
+
+func (suite *EventSuite) TestBus() {
+	// publish event without subscribers
+	event.Bus().Publish(event.Shutdown)
+
+	subscriber1 := make(chan event.Type, 1)
+	subscriber2 := make(chan event.Type, 1)
+
+	event.Bus().Subscribe(subscriber1)
+	defer event.Bus().Unsubscribe(subscriber1)
+
+	event.Bus().Subscribe(subscriber2)
+	defer event.Bus().Unsubscribe(subscriber2)
+
+	select {
+	case <-subscriber1:
+		suite.Require().Fail("no previous messages should be delivered")
+	default:
+	}
+
+	// test fan-out
+	event.Bus().Publish(event.Reboot)
+
+	suite.Assert().Equal(event.Reboot, <-subscriber1)
+	suite.Assert().Equal(event.Reboot, <-subscriber2)
+
+	event.Bus().Unsubscribe(subscriber2)
+
+	event.Bus().Publish(event.Upgrade)
+
+	select {
+	case <-subscriber2:
+		suite.Require().Fail("message to subscriber2 should not be delivered")
+	default:
+	}
+	suite.Assert().Equal(event.Upgrade, <-subscriber1)
+}
+
+func TestEventSuite(t *testing.T) {
+	suite.Run(t, new(EventSuite))
+}