Add Must(*Logger, error) *Logger function (#1105)

example_test.go

@@ -91,10 +91,7 @@ func Example_basicConfiguration() {
 	if err := json.Unmarshal(rawJSON, &cfg); err != nil {
 		panic(err)
 	}
-	logger, err := cfg.Build()
-	if err != nil {
-		panic(err)
-	}
+	logger := zap.Must(cfg.Build())
 	defer logger.Sync()
 
 	logger.Info("logger construction succeeded")
@@ -278,10 +275,7 @@ func ExampleAtomicLevel_config() {
 	if err := json.Unmarshal(rawJSON, &cfg); err != nil {
 		panic(err)
 	}
-	logger, err := cfg.Build()
-	if err != nil {
-		panic(err)
-	}
+	logger := zap.Must(cfg.Build())
 	defer logger.Sync()
 
 	logger.Info("info logging enabled")

logger.go

@@ -107,6 +107,19 @@ func NewDevelopment(options ...Option) (*Logger, error) {
 	return NewDevelopmentConfig().Build(options...)
 }
 
+// Must is a helper that wraps a call to a function returning (*Logger, error)
+// and panics if the error is non-nil. It is intended for use in variable
+// initialization such as:
+//
+//     var logger := zap.Must(zap.NewProduction())
+func Must(logger *Logger, err error) *Logger {
+	if err != nil {
+		panic(err)
+	}
+
+	return logger
+}
+
 // NewExample builds a Logger that's designed for use in zap's testable
 // examples. It writes DebugLevel and above logs to standard out as JSON, but
 // omits the timestamp and calling function to keep example output

logger_test.go

@@ -628,6 +628,16 @@ func TestNopLogger(t *testing.T) {
 	})
 }
 
+func TestMust(t *testing.T) {
+	t.Run("must without an error does not panic", func(t *testing.T) {
+		assert.NotPanics(t, func() { Must(NewNop(), nil) }, "must paniced with no error")
+	})
+
+	t.Run("must with an error panics", func(t *testing.T) {
+		assert.Panics(t, func() { Must(nil, errors.New("an error")) }, "must did not panic with an error")
+	})
+}
+
 func infoLog(logger *Logger, msg string, fields ...Field) {
 	logger.Info(msg, fields...)
 }