Define environment variables to be injected in the test file processes

docs/06-configuration.md

@@ -30,6 +30,9 @@ To ignore files, prefix the pattern with an `!` (exclamation mark).
 		"concurrency": 5,
 		"failFast": true,
 		"failWithoutAssertions": false,
+		"environmentVariables": {
+			"MY_ENVIRONMENT_VARIABLE": "some value"
+		},
 		"tap": true,
 		"verbose": true,
 		"compileEnhancements": false,
@@ -57,6 +60,7 @@ Arguments passed to the CLI will always take precedence over the CLI options con
 - `cache`: cache compiled test and helper files under `node_modules/.cache/ava`. If `false`, files are cached in a temporary directory instead
 - `failFast`: stop running further tests once a test fails
 - `failWithoutAssertions`: if `false`, does not fail a test if it doesn't run [assertions](./03-assertions.md)
+- `environmentVariables`: specifies environment variables to be made available to the tests. The environment variables defined here override the ones from `process.env`
 - `tap`: if `true`, enables the [TAP reporter](./05-command-line.md#tap-reporter)
 - `verbose`: if `true`, enables verbose output
 - `snapshotDir`: specifies a fixed location for storing snapshot files. Use this if your snapshots are ending up in the wrong location

lib/cli.js

@@ -163,6 +163,7 @@ exports.run = async () => { // eslint-disable-line complexity
 	const babelPipeline = require('./babel-pipeline');
 	const normalizeExtensions = require('./extensions');
 	const {normalizeGlobs} = require('./globs');
+	const validateEnvironmentVariables = require('./environment-variables');
 
 	let babelConfig = null;
 	try {
@@ -171,6 +172,13 @@ exports.run = async () => { // eslint-disable-line complexity
 		exit(error.message);
 	}
 
+	let environmentVariables;
+	try {
+		environmentVariables = validateEnvironmentVariables(conf.environmentVariables);
+	} catch (error) {
+		exit(error.message);
+	}
+
 	let extensions;
 	try {
 		extensions = normalizeExtensions(conf.extensions || [], babelConfig);
@@ -206,6 +214,7 @@ exports.run = async () => { // eslint-disable-line complexity
 		failFast: conf.failFast,
 		failWithoutAssertions: conf.failWithoutAssertions !== false,
 		globs,
+		environmentVariables,
 		match,
 		parallelRuns,
 		projectDir,

lib/environment-variables.js

@@ -0,0 +1,16 @@
+'use strict';
+function validateEnvironmentVariables(environmentVariables) {
+	if (!environmentVariables) {
+		return {};
+	}
+
+	for (const value of Object.values(environmentVariables)) {
+		if (typeof value !== 'string') {
+			throw new TypeError('The \'environmentVariables\' configuration must be an object containing string values.');
+		}
+	}
+
+	return environmentVariables;
+}
+
+module.exports = validateEnvironmentVariables;

lib/fork.js

@@ -9,20 +9,20 @@ if (fs.realpathSync(__filename) !== __filename) {
 	console.warn('WARNING: `npm link ava` and the `--preserve-symlink` flag are incompatible. We have detected that AVA is linked via `npm link`, and that you are using either an early version of Node 6, or the `--preserve-symlink` flag. This breaks AVA. You should upgrade to Node 6.2.0+, avoid the `--preserve-symlink` flag, or avoid using `npm link ava`.');
 }
 
-const env = {NODE_ENV: 'test', ...process.env};
+// In case the test file imports a different AVA install,
+// the presence of this variable allows it to require this one instead
+const AVA_PATH = path.resolve(__dirname, '..');
 
 // Ensure NODE_PATH paths are absolute
-if (env.NODE_PATH) {
-	env.NODE_PATH = env.NODE_PATH
+let NODE_PATH;
+
+if (process.env.NODE_PATH) {
+	NODE_PATH = process.env.NODE_PATH
 		.split(path.delimiter)
 		.map(x => path.resolve(x))
 		.join(path.delimiter);
 }
 
-// In case the test file imports a different AVA install,
-// the presence of this variable allows it to require this one instead
-env.AVA_PATH = path.resolve(__dirname, '..');
-
 const describeTTY = tty => ({
 	colorDepth: tty.getColorDepth ? tty.getColorDepth() : undefined,
 	columns: tty.columns || 80,
@@ -56,7 +56,7 @@ module.exports = (file, opts, execArgv) => {
 	const subprocess = childProcess.fork(workerPath, args, {
 		cwd: opts.projectDir,
 		silent: true,
-		env,
+		env: {NODE_ENV: 'test', ...process.env, ...opts.environmentVariables, AVA_PATH, NODE_PATH},
 		execArgv: execArgv || process.execArgv
 	});
 

test/fixture/environment-variables/ava.config.js

@@ -0,0 +1,5 @@
+const config = require('.');
+
+export default {
+	environmentVariables: {[config.name]: config.value}
+};

test/fixture/environment-variables/index.js

@@ -0,0 +1,6 @@
+'use strict';
+
+module.exports = {
+	name: 'MY_ENVIRONMENT_VARIABLE',
+	value: 'some value'
+};

test/fixture/environment-variables/package.json

@@ -0,0 +1 @@
+{}

test/fixture/environment-variables/test.js

@@ -0,0 +1,6 @@
+import test from '../../..';
+import {name, value} from '.';
+
+test('works', t => {
+	t.is(process.env[name], value);
+});

test/fixture/invalid-environment-variables/package.json

@@ -0,0 +1,7 @@
+{
+	"ava": {
+		"environmentVariables": {
+			"SOME_INVALID_ENVIRONMENT_VARIABLE": {}
+		}
+	}
+}

test/integration/environment-variables.js

@@ -0,0 +1,36 @@
+'use strict';
+const {test} = require('tap');
+const figures = require('figures');
+const {execCli} = require('../helper/cli');
+const {name, value} = require('../fixture/environment-variables');
+
+test('sets default environment variables from the config', t => {
+	execCli(['test.js'], {dirname: 'fixture/environment-variables'}, (err, stdout) => {
+		t.ifError(err);
+		t.match(stdout, /1 test passed/);
+		t.end();
+	});
+});
+
+test('overrides environment variables provided through the CLI', t => {
+	const env = {[name]: `${value} (updated)`};
+
+	execCli(['test.js'], {dirname: 'fixture/environment-variables', env}, (err, stdout) => {
+		t.ifError(err);
+		t.match(stdout, /1 test passed/);
+		t.end();
+	});
+});
+
+test('errors if environment variables are not string values', t => {
+	execCli(['es2015.js'], {dirname: 'fixture/invalid-environment-variables'}, (err, stdout, stderr) => {
+		t.ok(err);
+
+		let expectedOutput = '\n';
+		expectedOutput += figures.cross + ' The \'environmentVariables\' configuration must be an object containing string values.';
+		expectedOutput += '\n';
+
+		t.is(stderr, expectedOutput);
+		t.end();
+	});
+});