From 374dd734169c335c4c38fcbe848971bd037483f4 Mon Sep 17 00:00:00 2001
From: Joel Purra <code+github@joelpurra.com>
Date: Mon, 21 Jun 2021 11:30:30 +0200
Subject: [PATCH] Support `xo.config.cjs` and `.xo-config.cjs` (#561)

---
 lib/constants.js                                        | 4 +++-
 readme.md                                               | 8 ++++++++
 test/fixtures/config-files/xo-config_cjs/.xo-config.cjs | 3 +++
 test/fixtures/config-files/xo-config_cjs/file.js        | 5 +++++
 test/fixtures/config-files/xo_config_cjs/file.js        | 5 +++++
 test/fixtures/config-files/xo_config_cjs/xo.config.cjs  | 3 +++
 test/lint-files.js                                      | 2 ++
 test/lint-text.js                                       | 2 ++
 8 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 test/fixtures/config-files/xo-config_cjs/.xo-config.cjs
 create mode 100644 test/fixtures/config-files/xo-config_cjs/file.js
 create mode 100644 test/fixtures/config-files/xo_config_cjs/file.js
 create mode 100644 test/fixtures/config-files/xo_config_cjs/xo.config.cjs

diff --git a/lib/constants.js b/lib/constants.js
index aa3ce5fb..570f9016 100644
--- a/lib/constants.js
+++ b/lib/constants.js
@@ -120,7 +120,9 @@ const CONFIG_FILES = [
 	`.${MODULE_NAME}-config`,
 	`.${MODULE_NAME}-config.json`,
 	`.${MODULE_NAME}-config.js`,
-	`${MODULE_NAME}.config.js`
+	`.${MODULE_NAME}-config.cjs`,
+	`${MODULE_NAME}.config.js`,
+	`${MODULE_NAME}.config.cjs`
 ];
 
 const TSCONFIG_DEFFAULTS = {
diff --git a/readme.md b/readme.md
index 5347b5aa..32cdba33 100644
--- a/readme.md
+++ b/readme.md
@@ -160,6 +160,14 @@ module.exports = {
 };
 ```
 
+4. For [ECMAScript module (ESM)](https://nodejs.org/api/esm.html) packages with [`"type": "module"`](https://nodejs.org/api/packages.html#packages_type), as a JavaScript module in `.xo-config.cjs` or `xo.config.cjs`:
+
+```js
+module.exports = {
+	space: true
+};
+```
+
 [Globals](https://eslint.org/docs/user-guide/configuring#specifying-globals) and [rules](https://eslint.org/docs/user-guide/configuring#configuring-rules) can be configured inline in files.
 
 ### envs
diff --git a/test/fixtures/config-files/xo-config_cjs/.xo-config.cjs b/test/fixtures/config-files/xo-config_cjs/.xo-config.cjs
new file mode 100644
index 00000000..3c3e28a5
--- /dev/null
+++ b/test/fixtures/config-files/xo-config_cjs/.xo-config.cjs
@@ -0,0 +1,3 @@
+module.exports = {
+	space: true
+};
diff --git a/test/fixtures/config-files/xo-config_cjs/file.js b/test/fixtures/config-files/xo-config_cjs/file.js
new file mode 100644
index 00000000..eb542496
--- /dev/null
+++ b/test/fixtures/config-files/xo-config_cjs/file.js
@@ -0,0 +1,5 @@
+const object = {
+	a: 1
+};
+
+console.log(object.a);
diff --git a/test/fixtures/config-files/xo_config_cjs/file.js b/test/fixtures/config-files/xo_config_cjs/file.js
new file mode 100644
index 00000000..eb542496
--- /dev/null
+++ b/test/fixtures/config-files/xo_config_cjs/file.js
@@ -0,0 +1,5 @@
+const object = {
+	a: 1
+};
+
+console.log(object.a);
diff --git a/test/fixtures/config-files/xo_config_cjs/xo.config.cjs b/test/fixtures/config-files/xo_config_cjs/xo.config.cjs
new file mode 100644
index 00000000..3c3e28a5
--- /dev/null
+++ b/test/fixtures/config-files/xo_config_cjs/xo.config.cjs
@@ -0,0 +1,3 @@
+module.exports = {
+	space: true
+};
diff --git a/test/lint-files.js b/test/lint-files.js
index 5821b549..ab1144df 100644
--- a/test/lint-files.js
+++ b/test/lint-files.js
@@ -278,6 +278,8 @@ async function configType(t, {dir}) {
 configType.title = (_, {type}) => `load config from ${type}`.trim();
 
 test(configType, {type: 'xo.config.js', dir: 'xo-config_js'});
+test(configType, {type: 'xo.config.cjs', dir: 'xo-config_cjs'});
 test(configType, {type: '.xo-config.js', dir: 'xo-config_js'});
+test(configType, {type: '.xo-config.cjs', dir: 'xo-config_cjs'});
 test(configType, {type: '.xo-config.json', dir: 'xo-config_json'});
 test(configType, {type: '.xo-config', dir: 'xo-config'});
diff --git a/test/lint-text.js b/test/lint-text.js
index 93312121..d365cfbb 100644
--- a/test/lint-text.js
+++ b/test/lint-text.js
@@ -324,6 +324,8 @@ async function configType(t, {dir}) {
 configType.title = (_, {type}) => `load config from ${type}`.trim();
 
 test(configType, {type: 'xo.config.js', dir: 'xo-config_js'});
+test(configType, {type: 'xo.config.cjs', dir: 'xo-config_cjs'});
 test(configType, {type: '.xo-config.js', dir: 'xo-config_js'});
+test(configType, {type: '.xo-config.cjs', dir: 'xo-config_cjs'});
 test(configType, {type: '.xo-config.json', dir: 'xo-config_json'});
 test(configType, {type: '.xo-config', dir: 'xo-config'});