logging/zap/ctxzap: add shorthand functions (#408)

Fixes #407

logging/zap/ctxzap/context.go

@@ -62,3 +62,27 @@ func ToContext(ctx context.Context, logger *zap.Logger) context.Context {
 	}
 	return context.WithValue(ctx, ctxMarkerKey, l)
 }
+
+// Debug is equivalent to calling Debug on the zap.Logger in the context.
+// It is a no-op if the context does not contain a zap.Logger.
+func Debug(ctx context.Context, msg string, fields ...zap.Field) {
+	Extract(ctx).Debug(msg, fields...)
+}
+
+// Info is equivalent to calling Info on the zap.Logger in the context.
+// It is a no-op if the context does not contain a zap.Logger.
+func Info(ctx context.Context, msg string, fields ...zap.Field) {
+	Extract(ctx).Info(msg, fields...)
+}
+
+// Warn is equivalent to calling Warn on the zap.Logger in the context.
+// It is a no-op if the context does not contain a zap.Logger.
+func Warn(ctx context.Context, msg string, fields ...zap.Field) {
+	Extract(ctx).Warn(msg, fields...)
+}
+
+// Error is equivalent to calling Error on the zap.Logger in the context.
+// It is a no-op if the context does not contain a zap.Logger.
+func Error(ctx context.Context, msg string, fields ...zap.Field) {
+	Extract(ctx).Error(msg, fields...)
+}

logging/zap/ctxzap/context_test.go

@@ -0,0 +1,51 @@
+package ctxzap
+
+import (
+	"context"
+	"testing"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+	"go.uber.org/zap/zaptest"
+)
+
+func TestShorthands(t *testing.T) {
+	cases := []struct {
+		fn    func(ctx context.Context, msg string, fields ...zapcore.Field)
+		level zapcore.Level
+	}{
+		{Debug, zap.DebugLevel},
+		{Info, zap.InfoLevel},
+		{Warn, zap.WarnLevel},
+		{Error, zap.ErrorLevel},
+	}
+	const message = "omg!"
+	for _, c := range cases {
+		t.Run(c.level.String(), func(t *testing.T) {
+			called := false
+			logger := zaptest.NewLogger(t, zaptest.WrapOptions(zap.Hooks(func(e zapcore.Entry) error {
+				called = true
+				if e.Level != c.level {
+					t.Fatalf("Expected %v, got %v", c.level, e.Level)
+				}
+				if e.Message != message {
+					t.Fatalf("message: expected %v, got %v", message, e.Message)
+				}
+				return nil
+			})))
+			ctx := ToContext(context.Background(), logger)
+			c.fn(ctx, message)
+			if !called {
+				t.Fatal("hook not called")
+			}
+		})
+	}
+}
+
+func TestShorthandsNoop(t *testing.T) {
+	// Just check we don't panic if there is no logger in the context.
+	Debug(context.Background(), "no-op")
+	Info(context.Background(), "no-op")
+	Warn(context.Background(), "no-op")
+	Error(context.Background(), "no-op")
+}