Add support for configuration files with ".jsonc" extension (#3760); closes #3753

Author: sstephant

docs/index.md

@@ -1627,7 +1627,7 @@ In addition to supporting the legacy [`mocha.opts`](#mochaopts) run-control form
 
 - **JavaScript**: Create a `.mocharc.js` in your project's root directory, and export an object (`module.exports = {/* ... */}`) containing your configuration.
 - **YAML**: Create a `.mocharc.yaml` (or `.mocharc.yml`) in your project's root directory.
-- **JSON**: Create a `.mocharc.json` in your project's root directory. Comments — while not valid JSON — are allowed in this file, and will be ignored by Mocha.
+- **JSON**: Create a `.mocharc.json` (or `.mocharc.jsonc`) in your project's root directory. Comments — while not valid JSON — are allowed in this file, and will be ignored by Mocha.
 - **`package.json`**: Create a `mocha` property in your project's `package.json`.
 
 Mocha suggests using one of the above strategies for configuration instead of the legacy `mocha.opts` format.
@@ -1649,6 +1649,7 @@ If no custom path was given, and if there are multiple configuration files in th
 1. `.mocharc.js`
 1. `.mocharc.yaml`
 1. `.mocharc.yml`
+1. `.mocharc.jsonc`
 1. `.mocharc.json`
 
 ### Merging

example/config/.mocharc.jsonc

@@ -0,0 +1,14 @@
+// This config file contains Mocha's defaults.
+// As you can see, comments are allowed.
+// This same configuration could be provided in the `mocha` property of your
+// project's `package.json`.
+{
+  "diff": true,
+  "extension": ["js"],
+  "opts": "./test/mocha.opts",
+  "package": /* 📦 */ "./package.json",
+  "reporter": /* 📋 */ "spec",
+  "slow": 75,
+  "timeout": 2000,
+  "ui": "bdd"
+}

lib/cli/config.js

@@ -24,6 +24,7 @@ exports.CONFIG_FILES = [
   '.mocharc.js',
   '.mocharc.yaml',
   '.mocharc.yml',
+  '.mocharc.jsonc',
   '.mocharc.json'
 ];
 

test/node-unit/cli/config.spec.js

@@ -24,7 +24,7 @@ describe('cli/config', function() {
         sandbox.stub(parsers, 'js').returns(config);
       });
 
-      describe('when supplied a filepath with .yaml extension', function() {
+      describe('when supplied a filepath with ".yaml" extension', function() {
         const filepath = 'foo.yaml';
 
         it('should use the YAML parser', function() {
@@ -35,7 +35,7 @@ describe('cli/config', function() {
         });
       });
 
-      describe('when supplied a filepath with .yml extension', function() {
+      describe('when supplied a filepath with ".yml" extension', function() {
         const filepath = 'foo.yml';
 
         it('should use the YAML parser', function() {
@@ -46,7 +46,7 @@ describe('cli/config', function() {
         });
       });
 
-      describe('when supplied a filepath with .js extension', function() {
+      describe('when supplied a filepath with ".js" extension', function() {
         const filepath = 'foo.js';
 
         it('should use the JS parser', function() {
@@ -57,7 +57,18 @@ describe('cli/config', function() {
         });
       });
 
-      describe('when supplied a filepath with .json extension', function() {
+      describe('when supplied a filepath with ".jsonc" extension', function() {
+        const filepath = 'foo.jsonc';
+
+        it('should use the JSON parser', function() {
+          loadConfig('foo.jsonc');
+          expect(parsers.json, 'to have calls satisfying', [
+            {args: [filepath], returned: config}
+          ]).and('was called times', 1);
+        });
+      });
+
+      describe('when supplied a filepath with ".json" extension', function() {
         const filepath = 'foo.json';
 
         it('should use the JSON parser', function() {