Added stopper module tests.

Author: vvuwei

pkg/modules/stopper/stopper_test.go

@@ -0,0 +1,32 @@
+package stopper
+
+import (
+	"context"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestStopperCallsStop(t *testing.T) {
+	stopWasCalled := false
+
+	var stopFunc context.CancelFunc = func() {
+		stopWasCalled = true
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	stopperModule := NewModule(stopFunc)
+	stopperModule.Start(ctx)
+
+	stopperInput, err := stopperModule.Input(InputName)
+	assert.NoError(t, err)
+
+	// Act: send stop signal to stopper
+	stopperInput.Push(struct{}{})
+
+	err = stopperModule.Close()
+	assert.NoError(t, err)
+
+	assert.True(t, stopWasCalled, "stop was never called")
+}