From a78e02e8253fcfd6c443eb130b10b91f3bcf7966 Mon Sep 17 00:00:00 2001
From: Pierre Vanduynslager <pierre.denis.vanduynslager@gmail.com>
Date: Wed, 10 Jan 2018 15:11:26 -0500
Subject: [PATCH] Set target engines to 8 for default AVA files

---
 index.js                |  2 +-
 lib/options-manager.js  | 23 +++++++++++++++++++++++
 readme.md               | 19 -------------------
 test/options-manager.js | 21 +++++++++++++++++++++
 4 files changed, 45 insertions(+), 20 deletions(-)

diff --git a/index.js b/index.js
index b042ed94..a0526303 100644
--- a/index.js
+++ b/index.js
@@ -42,7 +42,7 @@ const runEslint = (paths, opts) => {
 module.exports.lintText = (str, opts) => {
 	opts = optionsManager.preprocess(opts);
 
-	if (opts.overrides && opts.overrides.length > 0) {
+	if (opts.overrides && opts.overrides.length > 0 && opts.filename) {
 		const overrides = opts.overrides;
 		delete opts.overrides;
 
diff --git a/lib/options-manager.js b/lib/options-manager.js
index 681d6a97..4fd75fcd 100644
--- a/lib/options-manager.js
+++ b/lib/options-manager.js
@@ -30,6 +30,16 @@ const DEFAULT_EXTENSION = [
 	'jsx'
 ];
 
+const AVA_NODE_TARGET = 8;
+
+const AVA_DEFAULT_FILES = [
+	'test.js',
+	'test-*.js',
+	'test',
+	'**/__tests__',
+	'**/*.test.js'
+];
+
 const DEFAULT_CONFIG = {
 	useEslintrc: false,
 	cache: true,
@@ -325,10 +335,21 @@ const getIgnores = opts => {
 	return opts;
 };
 
+const getDefaultOverrides = opts => {
+	// Only apply if the user uses AVA, and the `engines.node` supoort Node version lower than AVA target
+	if (opts.cwd && resolveFrom.silent(opts.cwd, 'ava') && (!opts.engines || !opts.engines.node || !semver.validRange(opts.engines.node) || semver.intersects(opts.engines.node, `<${AVA_NODE_TARGET}`))) {
+		opts.overrides = arrify(opts.overrides);
+		opts.overrides.push(mergeWith({}, {files: AVA_DEFAULT_FILES}, {engines: {nodes: `>=${AVA_NODE_TARGET}`}}));
+	}
+
+	return opts;
+};
+
 const preprocess = opts => {
 	opts = mergeWithPkgConf(opts);
 	opts = normalizeOpts(opts);
 	opts = getIgnores(opts);
+	opts = getDefaultOverrides(opts);
 	opts.extensions = DEFAULT_EXTENSION.concat(opts.extensions || []);
 
 	return opts;
@@ -336,6 +357,7 @@ const preprocess = opts => {
 
 module.exports.DEFAULT_IGNORE = DEFAULT_IGNORE;
 module.exports.DEFAULT_CONFIG = DEFAULT_CONFIG;
+module.exports.AVA_DEFAULT_FILES = AVA_DEFAULT_FILES;
 module.exports.mergeWithPkgConf = mergeWithPkgConf;
 module.exports.mergeWithPrettierConf = mergeWithPrettierConf;
 module.exports.normalizeOpts = normalizeOpts;
@@ -346,3 +368,4 @@ module.exports.groupConfigs = groupConfigs;
 module.exports.preprocess = preprocess;
 module.exports.emptyOptions = emptyOptions;
 module.exports.getIgnores = getIgnores;
+module.exports.getDefaultOverrides = getDefaultOverrides;
diff --git a/readme.md b/readme.md
index 9d84c802..0d73de7e 100644
--- a/readme.md
+++ b/readme.md
@@ -313,25 +313,6 @@ If you have a directory structure with nested `package.json` files and you want
 
 Put a `package.json` with your config at the root and add `"xo": false` to the `package.json` in your bundled packages.
 
-### Transpilation
-
-If some files in your project are transpiled in order to support an older Node version you can use the [Config Overrides](#config-overrides) option to set a specific [nodeVersion](#nodeversion) target to these files.
-
-For example, if your project targets Node 4 (your `package.json` is configured with `engines.node` to `>=4`) and you are using [AVA](https://github.com/avajs/ava), then your test files are automatically transpiled. You can override `nodeVersion` for the tests files:
-
-```json
-{
-	"xo": {
-		"overrides": [
-			{
-				"files": "{test,tests,spec,__tests__}/**/*.js",
-				"nodeVersion": ">=9"
-			}
-		]
-	}
-}
-```
-
 
 ## FAQ
 
diff --git a/test/options-manager.js b/test/options-manager.js
index bcd9ff8a..916941c7 100644
--- a/test/options-manager.js
+++ b/test/options-manager.js
@@ -382,3 +382,24 @@ test('mergeWithPkgConf: XO engine options false supersede package.json\'s', t =>
 	const expected = Object.assign({}, {engines: false}, {cwd});
 	t.deepEqual(result, expected);
 });
+
+test('getDefaultOverrides: add AVA override if node engine <=8', t => {
+	const cwd = path.resolve('fixtures', 'engines');
+	const config = manager.getDefaultOverrides({cwd, engines: {node: '>=4'}});
+
+	t.deepEqual(config.overrides, [{engines: {nodes: '>=8'}, files: manager.AVA_DEFAULT_FILES}]);
+});
+
+test('getDefaultOverrides: add AVA override is node engine undefined', t => {
+	const cwd = path.resolve('fixtures', 'engines');
+	const config = manager.getDefaultOverrides({cwd});
+
+	t.deepEqual(config.overrides, [{engines: {nodes: '>=8'}, files: manager.AVA_DEFAULT_FILES}]);
+});
+
+test('getDefaultOverrides: Ado not add AVA override if node engine >=8', t => {
+	const cwd = path.resolve('fixtures', 'engines');
+	const config = manager.getDefaultOverrides({cwd, engines: {node: '>=8'}});
+
+	t.is(config.overrides, undefined);
+});