chore: import upstream snapshot with attribution

config/source/file/watcher_test.go

@@ -0,0 +1,120 @@
+package file_test
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"go-micro.dev/v6/config/source"
+	"go-micro.dev/v6/config/source/file"
+)
+
+// createTestFile a local helper to creates a temporary file with the given data
+func createTestFile(data []byte) (*os.File, func(), string, error) {
+	path := filepath.Join(os.TempDir(), fmt.Sprintf("file.%d", time.Now().UnixNano()))
+	fh, err := os.Create(path)
+	if err != nil {
+		return nil, func() {}, "", err
+	}
+
+	_, err = fh.Write(data)
+	if err != nil {
+		return nil, func() {}, "", err
+	}
+
+	return fh, func() {
+		fh.Close()
+		os.Remove(path)
+	}, path, err
+}
+
+func TestWatcher(t *testing.T) {
+	data := []byte(`{"foo": "bar"}`)
+	fh, cleanup, path, err := createTestFile(data)
+	if err != nil {
+		t.Error(err)
+	}
+	defer cleanup()
+
+	f := file.NewSource(file.WithPath(path))
+	if err != nil {
+		t.Error(err)
+	}
+
+	// create a watcher
+	w, err := f.Watch()
+	if err != nil {
+		t.Error(err)
+	}
+
+	newdata := []byte(`{"foo": "baz"}`)
+
+	go func() {
+		sc, err := w.Next()
+		if err != nil {
+			t.Error(err)
+			return
+		}
+
+		if !bytes.Equal(sc.Data, newdata) {
+			t.Error("expected data to be different")
+		}
+	}()
+
+	// rewrite to the file to trigger a change
+	_, err = fh.WriteAt(newdata, 0)
+	if err != nil {
+		t.Error(err)
+	}
+
+	// wait for the underlying watcher to detect changes
+	time.Sleep(time.Second)
+}
+
+func TestWatcherStop(t *testing.T) {
+	data := []byte(`{"foo": "bar"}`)
+	_, cleanup, path, err := createTestFile(data)
+	if err != nil {
+		t.Error(err)
+	}
+	defer cleanup()
+
+	src := file.NewSource(file.WithPath(path))
+	if err != nil {
+		t.Error(err)
+	}
+
+	// create a watcher
+	w, err := src.Watch()
+	if err != nil {
+		t.Error(err)
+	}
+
+	defer func() {
+		var err error
+		c := make(chan struct{})
+		defer close(c)
+
+		go func() {
+			_, err = w.Next()
+			c <- struct{}{}
+		}()
+
+		select {
+		case <-time.After(2 * time.Second):
+			err = errors.New("timeout waiting for Watcher.Next() to return")
+		case <-c:
+		}
+
+		if !errors.Is(err, source.ErrWatcherStopped) {
+			t.Error(err)
+		}
+	}()
+
+	// stop the watcher
+	w.Stop()
+}