Native types exceptions can crash Mocha

- Any non-extensible type thrown in an async callback raises an exception in Mocha runner, stopping tests.
mochajs · Apr 12, 2018 · 41fe763 · 41fe763
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commit 41fe763
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diff --git a/lib/runner.js b/lib/runner.js
@@ -704,6 +704,9 @@ Runner.prototype.uncaught = function (err) {
     debug('uncaught undefined exception');
     err = undefinedError();
   }
+  if (!(err instanceof Error || (err && typeof err.message === 'string'))) {
+    err = new Error('the ' + type(err) + ' ' + stringify(err) + ' was thrown, throw an Error :)');
+  }
   err.uncaught = true;
 
   var runnable = this.currentRunnable;

diff --git a/test/unit/throw.spec.js b/test/unit/throw.spec.js
@@ -26,6 +26,24 @@ describe('a test that throws', function () {
     });
   });
 
+  describe('extensible', function () {
+    it('should not crash if throwing non-extensible type', function (done) {
+      var test = new Test('im async and throw string async', function (done2) {
+        process.nextTick(function () {
+          throw 'error';
+        });
+      });
+      suite.addTest(test);
+      runner = new Runner(suite);
+      runner.on('end', function () {
+        expect(runner.failures).to.equal(1);
+        expect(test.state).to.equal('failed');
+        done();
+      });
+      runner.run();
+    });
+  });
+
   describe('undefined', function () {
     it('should not pass if throwing sync and test is sync', function (done) {
       var test = new Test('im sync and throw undefined sync', function () {