slog: fix race failures

The race detector messes with tests that measure allocations,
so disable those tests when it is running.

Fixes golang/go#54978.

Change-Id: I5e8e720f6a91f11257bcbb267927a236b2dfdafc
Reviewed-on: https://go-review.googlesource.com/c/exp/+/430075
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
Run-TryBot: Jonathan Amsterdam <[email protected]>

Author: jba

slog/attr_test.go

@@ -103,26 +103,24 @@ func TestAttrNoAlloc(t *testing.T) {
 	_ = x
 }
 
-func TestAnyLevel(t *testing.T) {
+func TestAnyLevelAlloc(t *testing.T) {
 	// Because typical Levels are small integers,
 	// they are zero-alloc.
 	var a Attr
 	x := DebugLevel + 100
 	wantAllocs(t, 0, func() { a = Any("k", x) })
+	_ = a
+}
+
+func TestAnyLevel(t *testing.T) {
+	x := DebugLevel + 100
+	a := Any("k", x)
 	v := a.Value()
 	if _, ok := v.(Level); !ok {
 		t.Errorf("wanted Level, got %T", v)
 	}
 }
 
-func wantAllocs(t *testing.T, want int, f func()) {
-	t.Helper()
-	got := int(testing.AllocsPerRun(5, f))
-	if got != want {
-		t.Errorf("got %d allocs, want %d", got, want)
-	}
-}
-
 //////////////// Benchmark for accessing Attr values
 
 // The "As" form is the slowest.

slog/norace_test.go

@@ -0,0 +1,17 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !race
+
+package slog
+
+import "testing"
+
+func wantAllocs(t *testing.T, want int, f func()) {
+	t.Helper()
+	got := int(testing.AllocsPerRun(5, f))
+	if got != want {
+		t.Errorf("got %d allocs, want %d", got, want)
+	}
+}

slog/race_test.go

@@ -0,0 +1,13 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build race
+
+package slog
+
+import "testing"
+
+func wantAllocs(t *testing.T, want int, f func()) {
+	t.Log("skipping allocation tests with race detector")
+}