CLI: Include .mjs and .js in default test file extensions

This re-enables the `.mjs` test file that was converted
in commit 8808b04, which moved it to `main` but we test that
in package.json as `qunit test/main test/cli/` which means it wasn't
getting run anymore.

bin/qunit.js

@@ -10,7 +10,7 @@ const pkg = require('../package.json');
 const description = `Runs tests using the QUnit framework.
 
   Files should be a space-separated list of files, directories, or glob expressions.
-  Defaults to 'test/**/*.js'.
+  Defaults to 'test/**/*.{js,mjs,cjs}'.
 
   For more info on working with QUnit, check out https://qunitjs.com.`;
 

src/cli/utils.js

@@ -29,8 +29,7 @@ function getFilesFromArgs (args) {
 
   // Default to files in the test directory
   if (!patterns.length) {
-    // TODO: In QUnit 3.0, change the default to {js,mjs}
-    patterns.push('test/**/*.js');
+    patterns.push('test/**/*.{js,mjs,cjs}');
   }
 
   const files = new Set();
@@ -47,8 +46,7 @@ function getFilesFromArgs (args) {
       files.add(pattern);
     } else {
       if (stat && stat.isDirectory()) {
-        // TODO: In QUnit 3.0, change the default to {js,mjs}
-        pattern = `${pattern}/**/*.js`;
+        pattern = `${pattern}/**/*.{js,mjs,cjs}`;
       }
       const results = glob(pattern, {
         cwd: process.cwd(),