chore(config/env): polish watcher

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()
+	})
+}