Revert "Test Sync() call when calling AddSync"

This reverts commit 9da32f3.

zapcore/write_syncer.go

@@ -40,26 +40,12 @@ type WriteSyncer interface {
 func AddSync(w io.Writer) WriteSyncer {
 	switch w := w.(type) {
 	case WriteSyncer:
-		if !checkSync(w.(WriteSyncer)) {
-			return writerWrapper{w}
-		}
 		return w
 	default:
 		return writerWrapper{w}
 	}
 }
 
-// checkSync executes a Sync() on the WriteSyncer to check whether it operates
-// cleanly.  In the particular case of the WriteSyncer being a special file,
-// calling Sync will return an `os.ErrInvalid` error.  If, for whatever reason,
-// the call of `Sync()` returns an error, this will return a `false`.
-func checkSync(w WriteSyncer) bool {
-	if err := w.Sync(); err != nil {
-		return false
-	}
-	return true
-}
-
 type lockedWriteSyncer struct {
 	sync.Mutex
 	ws WriteSyncer

zapcore/write_syncer_test.go

@@ -23,8 +23,6 @@ package zapcore
 import (
 	"bytes"
 	"errors"
-	"io/ioutil"
-	"os"
 	"testing"
 
 	"io"
@@ -67,20 +65,6 @@ func TestAddSyncWriter(t *testing.T) {
 	assert.NoError(t, ws.Sync(), "Unexpected error calling a no-op Sync method.")
 }
 
-func TestCheckSync(t *testing.T) {
-	assert.False(t, checkSync(os.Stdout), "Expected os.Stdout to fail sync check")
-	assert.False(t, checkSync(os.Stderr), "Expected os.Stderr to fail sync check")
-
-	// Test a real file, which should pass
-	tmpFile, err := ioutil.TempFile("/tmp", "zapcore-test")
-	if err != nil {
-		t.SkipNow()
-		return
-	}
-	defer tmpFile.Close()
-	assert.True(t, checkSync(tmpFile), "Expected os.Stderr to fail sync check")
-}
-
 func TestMultiWriteSyncerWritesBoth(t *testing.T) {
 	first := &bytes.Buffer{}
 	second := &bytes.Buffer{}