chore(config/env): polish watcher (#1341)

* chore(config/env): polish watcher

config/env/watcher.go

@@ -7,8 +7,6 @@ import (
 )
 
 type watcher struct {
-	exit chan struct{}
-
 	ctx    context.Context
 	cancel context.CancelFunc
 }
@@ -17,7 +15,7 @@ var _ config.Watcher = (*watcher)(nil)
 
 func NewWatcher() (config.Watcher, error) {
 	ctx, cancel := context.WithCancel(context.Background())
-	return &watcher{exit: make(chan struct{}), ctx: ctx, cancel: cancel}, nil
+	return &watcher{ctx: ctx, cancel: cancel}, nil
 }
 
 // Next will be blocked until the Stop method is called
@@ -25,13 +23,10 @@ func (w *watcher) Next() ([]*config.KeyValue, error) {
 	select {
 	case <-w.ctx.Done():
 		return nil, w.ctx.Err()
-	case <-w.exit:
-		return nil, nil
 	}
 }
 
 func (w *watcher) Stop() error {
-	close(w.exit)
 	w.cancel()
 	return nil
 }

config/env/watcher_test.go

@@ -0,0 +1,29 @@
+package env
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_watcher_next(t *testing.T) {
+	t.Run("next after stop should return err", func(t *testing.T) {
+		w, err := NewWatcher()
+		require.NoError(t, err)
+
+		_ = w.Stop()
+		_, err = w.Next()
+		assert.Error(t, err)
+	})
+}
+
+func Test_watcher_stop(t *testing.T) {
+	t.Run("stop multiple times should not panic", func(t *testing.T) {
+		w, err := NewWatcher()
+		require.NoError(t, err)
+
+		_ = w.Stop()
+		_ = w.Stop()
+	})
+}