From f4429dba6ce45663a9d3898d1afe83cc9fa184fa Mon Sep 17 00:00:00 2001
From: Simon Knott <info@simonknott.de>
Date: Fri, 19 Jan 2024 10:01:26 +0100
Subject: [PATCH] fix: mute system logger in local dev (#458)

Follow-up to https://github.com/netlify/functions/pull/457. The system
logger shouldn't be visible in local dev.
---
 src/lib/system_logger.ts   |  6 ++++++
 test/unit/system_logger.js | 22 ++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/src/lib/system_logger.ts b/src/lib/system_logger.ts
index a6cc5046..80afab13 100644
--- a/src/lib/system_logger.ts
+++ b/src/lib/system_logger.ts
@@ -1,3 +1,5 @@
+import { env } from 'process'
+
 const systemLogTag = '__nfSystemLog'
 
 const serializeError = (error: Error): Record<string, unknown> => {
@@ -28,6 +30,10 @@ class SystemLogger {
   }
 
   private doLog(logger: typeof console.log, message: string) {
+    if (env.NETLIFY_DEV && !env.NETLIFY_ENABLE_SYSTEM_LOGGING) {
+      return
+    }
+
     logger(systemLogTag, JSON.stringify({ msg: message, fields: this.fields }))
   }
 
diff --git a/test/unit/system_logger.js b/test/unit/system_logger.js
index 2a1926c7..712dfb28 100644
--- a/test/unit/system_logger.js
+++ b/test/unit/system_logger.js
@@ -1,3 +1,5 @@
+const process = require("process")
+
 const test = require('ava')
 
 const { systemLogger, LogLevel } = require('../../dist/internal')
@@ -35,3 +37,23 @@ test('Fields', (t) => {
 
   console.log = originalLog
 })
+
+test('Local Dev', (t) => {
+  const originalLog = console.log
+  const logs = []
+  console.log = (...message) => logs.push(message)
+  systemLogger.log('hello!')
+  t.is(logs.length, 1)
+
+  process.env.NETLIFY_DEV= "true"
+  systemLogger.log('hello!')
+  t.is(logs.length, 1)
+
+  process.env.NETLIFY_ENABLE_SYSTEM_LOGGING= "true"
+  systemLogger.log('hello!')
+  t.is(logs.length, 2)
+
+  delete process.env.NETLIFY_DEV
+  delete process.env.NETLIFY_ENABLE_SYSTEM_LOGGING
+  console.log = originalLog
+})