feat: added optional jsw format to json reporter

docs/index.md

@@ -1970,6 +1970,8 @@ The JSON reporter outputs a single large JSON object when the tests have complet
 
 By default, it will output to the console. To write directly to a file, use `--reporter-option output=filename.json`.
 
+The indentation of the JSON reporter can be set with --reporter-option indentation=Number. Number being any integer. Alternatively, you can set the indentation to a tab character using --reporter-option indentation='\t'.
+
 ![json reporter](images/reporter-json.png?withoutEnlargement&resize=920,9999){:class="screenshot" loading="lazy"}
 
 ### JSON Stream

lib/reporters/json.js

@@ -78,7 +78,16 @@ function JSONReporter(runner, options = {}) {
 
     runner.testResults = obj;
 
-    var json = JSON.stringify(obj, null, 2);
+    const indentation = options.reporterOption?.indentation?? 2;
+
+    var json;
+
+    if (indentation === '\\t') {
+      json = JSON.stringify(obj, null, '\t');
+    } else {
+      json = JSON.stringify(obj, null, parseInt(indentation, 10));
+    }
+
     if (output) {
       try {
         fs.mkdirSync(path.dirname(output), {recursive: true});

test/reporters/json.spec.js

@@ -229,5 +229,19 @@ describe('JSON reporter', function () {
         'file output not supported in browser'
       );
     });
+
+    it('should set options.indentation with a number', function () {
+      var options = {indentation: 4};
+      var mochaReporter = new mocha._reporter(runner, options);
+
+      expect(mochaReporter.options.indentation, 'to be', 4);
+    });
+
+    it('should set options.indentation correctly with a tab', function () {
+      var options = {indentation: '\t'};
+      var mochaReporter = new mocha._reporter(runner, options);
+
+      expect(mochaReporter.options.indentation, 'to be', '\t');
+    });
   });
 });