fix: remove ansi escape sequences from escaped xunit output

lib/utils.js

@@ -33,7 +33,12 @@ exports.inherits = util.inherits;
  * @return {string}
  */
 exports.escape = function (html) {
-  return he.encode(String(html), {useNamedReferences: false});
+  return he
+    .encode(String(html), {useNamedReferences: false})
+    .replace(/&#x([0-9A-F]);/g, (match) => {
+      const val = Number.parseInt(match); 
+      return val === 0x9 || val === 0xA || val === 0xD || (val >= 0xE000 && val <= 0xFFFD) || (val >= 0x10000 && val <= 0x10FFFF) ? `&#x${match};` : '';
+    });
 };
 
 /**

test/integration/fixtures/ansi.fixture.js

@@ -0,0 +1,13 @@
+'use strict';
+
+var assert = require('assert');
+
+describe('suite', function () {
+  it('test1', function () {
+    assert(true);
+  });
+
+  it('test2', function () {
+    assert.ok(false, '\u001b[31mnot ok\u001b[39m');
+  });
+});

test/integration/reporters.spec.js

@@ -62,6 +62,32 @@ describe('reporters', function () {
         done(err);
       });
     });
+
+    it('does not include ansi escape sequences (issue: 4526)', function(done) {
+      var randomStr = crypto.randomBytes(8).toString('hex');
+      var tmpDir = os.tmpdir().replace(new RegExp(path.sep + '$'), '');
+      var tmpFile = tmpDir + path.sep + 'test-issue-4526-' + randomStr + '.xml';
+
+      var args = [
+        '--reporter=xunit',
+        '--reporter-options',
+        'output=' + tmpFile
+      ];
+      var unexpectedOutput = ['', ''];
+
+      run('ansi.fixture.js', args, function(err, result) {
+        if (err) return done(err);
+
+        var xml = fs.readFileSync(tmpFile, 'utf8');
+        fs.unlinkSync(tmpFile);
+
+        unexpectedOutput.forEach(function(line) {
+          expect(xml, 'not to contain', line);
+        });
+
+        done(err);
+      });
+    });
   });
 
   describe('loader', function () {