From e06e09a6d396031c89b87383eef3cad6f647cf2c Mon Sep 17 00:00:00 2001
From: Craig Pastro <craig.pastro@auth0.com>
Date: Fri, 3 Jun 2022 10:34:29 -0700
Subject: [PATCH] Add Must(*Logger, error) *Logger function (#1105)

---
 example_test.go | 10 ++--------
 logger.go       | 13 +++++++++++++
 logger_test.go  | 10 ++++++++++
 3 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/example_test.go b/example_test.go
index aecf41246..327e3ef39 100644
--- a/example_test.go
+++ b/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")
diff --git a/logger.go b/logger.go
index febc3d827..c84145d66 100644
--- a/logger.go
+++ b/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
diff --git a/logger_test.go b/logger_test.go
index c71306c7d..58b756a56 100644
--- a/logger_test.go
+++ b/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...)
 }