From e370117ff3fe963c9ec1cc538414961b306c00bd Mon Sep 17 00:00:00 2001
From: Sam Verschueren <sam.verschueren@gmail.com>
Date: Fri, 9 Jun 2017 16:41:54 +0200
Subject: [PATCH] Extend environment by default - fixes #87 (#88)

---
 fixtures/environment |  4 ++++
 index.js             |  4 ++++
 readme.md            |  9 ++++++++-
 test.js              | 19 +++++++++++++++++++
 4 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100755 fixtures/environment

diff --git a/fixtures/environment b/fixtures/environment
new file mode 100755
index 000000000..280faea9c
--- /dev/null
+++ b/fixtures/environment
@@ -0,0 +1,4 @@
+#!/usr/bin/env node
+'use strict';
+console.log(process.env.FOO);
+console.log(process.env.BAR);
diff --git a/index.js b/index.js
index bab0bd910..1169b398d 100644
--- a/index.js
+++ b/index.js
@@ -16,6 +16,10 @@ const TEN_MEGABYTES = 1000 * 1000 * 10;
 function handleArgs(cmd, args, opts) {
 	let parsed;
 
+	if (opts && opts.env && opts.extendEnv !== false) {
+		opts.env = Object.assign({}, process.env, opts.env);
+	}
+
 	if (opts && opts.__winShell === true) {
 		delete opts.__winShell;
 		parsed = {
diff --git a/readme.md b/readme.md
index 59bffeb3a..8a4a39df0 100644
--- a/readme.md
+++ b/readme.md
@@ -114,7 +114,14 @@ Current working directory of the child process.
 Type: `Object`<br>
 Default: `process.env`
 
-Environment key-value pairs.
+Environment key-value pairs. Extends automatically from `process.env`. Set `extendEnv` to `false` if you don't want this.
+
+#### extendEnv
+
+Type: `boolean`<br>
+Default: `true`
+
+Set to `false` if you don't want to extend the environment variables when providing the `env` property.
 
 #### argv0
 
diff --git a/test.js b/test.js
index 04eacddbc..5f67d6cd7 100644
--- a/test.js
+++ b/test.js
@@ -10,6 +10,7 @@ import tempfile from 'tempfile';
 import m from './';
 
 process.env.PATH = path.join(__dirname, 'fixtures') + path.delimiter + process.env.PATH;
+process.env.FOO = 'foo';
 
 test('execa()', async t => {
 	const {stdout} = await m('noop', ['foo']);
@@ -418,3 +419,21 @@ if (process.platform !== 'win32') {
 		}
 	});
 }
+
+test('extend environment variables by default', async t => {
+	const result = await m.stdout('environment', [], {env: {BAR: 'bar'}});
+
+	t.deepEqual(result.split('\n'), [
+		'foo',
+		'bar'
+	]);
+});
+
+test('do not extend environment with `envExtend` option', async t => {
+	const result = await m.stdout('environment', [], {env: {BAR: 'bar', PATH: process.env.PATH}, extendEnv: false});
+
+	t.deepEqual(result.split('\n'), [
+		'undefined',
+		'bar'
+	]);
+});