Watch for test files are crashed (#4614)

Signed-off-by: Outsider <outsideris@gmail.com>

Author: outsideris

lib/cli/watch-run.js

@@ -261,17 +261,21 @@ const createRerunner = (mocha, watcher, {beforeRun} = {}) => {
   let rerunScheduled = false;
 
   const run = () => {
-    mocha = beforeRun ? beforeRun({mocha, watcher}) || mocha : mocha;
-    runner = mocha.run(() => {
-      debug('finished watch run');
-      runner = null;
-      blastCache(watcher);
-      if (rerunScheduled) {
-        rerun();
-      } else {
-        console.error(`${logSymbols.info} [mocha] waiting for changes...`);
-      }
-    });
+    try {
+      mocha = beforeRun ? beforeRun({mocha, watcher}) || mocha : mocha;
+      runner = mocha.run(() => {
+        debug('finished watch run');
+        runner = null;
+        blastCache(watcher);
+        if (rerunScheduled) {
+          rerun();
+        } else {
+          console.error(`${logSymbols.info} [mocha] waiting for changes...`);
+        }
+      });
+    } catch (e) {
+      console.error(e.stack);
+    }
   };
 
   const scheduleRun = () => {

test/integration/helpers.js

@@ -470,6 +470,7 @@ async function runMochaWatchJSONAsync(args, opts, change) {
       // eslint-disable-next-line no-control-regex
       .replace(/\u001b\[\?25./g, '')
       .split('\u001b[2K')
+      .filter(x => x)
       .map(x => JSON.parse(x))
   );
 }

test/integration/options/watch.spec.js

@@ -47,6 +47,19 @@ describe('--watch', function() {
       });
     });
 
+    it('reruns test when watched test file crashes', function() {
+      const testFile = path.join(tempDir, 'test.js');
+      copyFixture(DEFAULT_FIXTURE, testFile);
+
+      replaceFileContents(testFile, 'done();', 'done((;');
+
+      return runMochaWatchJSONAsync([testFile], tempDir, () => {
+        replaceFileContents(testFile, 'done((;', 'done();');
+      }).then(results => {
+        expect(results, 'to have length', 1);
+      });
+    });
+
     describe('when in parallel mode', function() {
       it('reruns test when watched test file is touched', function() {
         const testFile = path.join(tempDir, 'test.js');
@@ -58,6 +71,19 @@ describe('--watch', function() {
           expect(results, 'to have length', 2);
         });
       });
+
+      it('reruns test when watched test file is crashed', function() {
+        const testFile = path.join(tempDir, 'test.js');
+        copyFixture(DEFAULT_FIXTURE, testFile);
+
+        replaceFileContents(testFile, 'done();', 'done((;');
+
+        return runMochaWatchJSONAsync([testFile], tempDir, () => {
+          replaceFileContents(testFile, 'done((;', 'done();');
+        }).then(results => {
+          expect(results, 'to have length', 1);
+        });
+      });
     });
 
     it('reruns test when file matching --watch-files changes', function() {