From d48e0d767b424062b6ba54f3eed8d76cd2d96f1d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=98yvind=20Saltvik?= <oyvind.saltvik@gmail.com>
Date: Tue, 14 Dec 2021 00:16:48 +0100
Subject: [PATCH] feat: added option to throw on missing env (#664)

* feat: added option to throw on missing env

* fix: passing tests for throwOnMissing
---
 README.md         |  2 ++
 index.js          |  1 +
 node.js           |  8 ++++++++
 test/main.test.js | 19 +++++++++++++++++++
 4 files changed, 30 insertions(+)

diff --git a/README.md b/README.md
index be6ac30f..0d250d6e 100644
--- a/README.md
+++ b/README.md
@@ -556,6 +556,8 @@ Options:
   Default is `false`.
 * `dangerousExtend`: Disable security checks for `extend` query.
   Default is `false`.
+* `throwOnMissing`: throw a error if env is not found.
+  Default is `false`.
 * `mobileToDesktop`: Use desktop browsers if Can I Use doesn’t have data
   about this mobile version. Can I Use has only data only about
   latest versions of mobile browsers. By default, `last 2 and_ff versions`
diff --git a/index.js b/index.js
index 73babdf1..8ef429df 100644
--- a/index.js
+++ b/index.js
@@ -397,6 +397,7 @@ var cache = {}
  *                                                     version in direct query.
  * @param {boolean} [opts.dangerousExtend] Disable security checks
  *                                         for extend query.
+ * @param {boolean} [opts.throwOnMissing] Throw error on missing env.
  * @param {boolean} [opts.mobileToDesktop] Alias mobile browsers to the desktop
  *                                         version when Can I Use doesn't have
  *                                         data about the specified version.
diff --git a/node.js b/node.js
index 0e869d36..66e69d25 100644
--- a/node.js
+++ b/node.js
@@ -82,6 +82,14 @@ function pickEnv(config, opts) {
     name = 'production'
   }
 
+  if (opts.throwOnMissing) {
+    if (name && name !== 'defaults' && !config[name]) {
+      throw new BrowserslistError(
+        'Missing config for Browserslist environment `' + name + '`.'
+      )
+    }
+  }
+  
   return config[name] || config.defaults
 }
 
diff --git a/test/main.test.js b/test/main.test.js
index b313d634..d0c1ae2b 100644
--- a/test/main.test.js
+++ b/test/main.test.js
@@ -260,4 +260,23 @@ test('correctly works with not and one-version browsers', () => {
   equal(browserslist('last 1 Baidu version, not <2% in AT'), ['baidu 7.12'])
 })
 
+test('throws error on missing env', () => {
+  throws(
+    () => browserslist(null, { path: PACKAGE, throwOnMissing: true, env: 'test' }),
+    "Missing config for Browserslist environment 'test'."
+  )
+})
+
+test('does not throw error on missing defaults env', () => {
+  equal(
+    browserslist(null, { path: PACKAGE, throwOnMissing: true, env: 'defaults' }), DEFAULTS
+  )
+})
+
+test('does not throw error on missing env', () => {
+  equal(
+    browserslist(null, { path: PACKAGE, throwOnMissing: false, env: 'test' }), DEFAULTS
+  )
+})
+
 test.run()