test(CheckedEntry): Reuse detection

Add a test for CheckedEntry re-use detection
that logs a message to ErrorOutput
when a CheckedEntry is accidentally reused.

zapcore/entry_ext_test.go

@@ -0,0 +1,55 @@
+// Copyright (c) 2023 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore_test
+
+import (
+	"bytes"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+	"go.uber.org/zap/zaptest"
+)
+
+func TestCheckedEntryIllegalReuse(t *testing.T) {
+	t.Parallel()
+
+	var errOut bytes.Buffer
+
+	testCore := zaptest.NewLogger(t).Core()
+	ce := testCore.Check(zapcore.Entry{
+		Level:   zapcore.InfoLevel,
+		Time:    time.Now(),
+		Message: "hello",
+	}, nil)
+	ce.ErrorOutput = zapcore.AddSync(&errOut)
+
+	// The first write should succeed.
+	ce.Write(zap.String("k", "v"), zap.Int("n", 42))
+	assert.Empty(t, errOut.String(), "Expected no errors on first write.")
+
+	// The second write should fail.
+	ce.Write(zap.String("foo", "bar"), zap.Int("x", 1))
+	assert.Contains(t, errOut.String(), "Unsafe CheckedEntry re-use near Entry",
+		"Expected error logged on second write.")
+}