try/catch plus test

example/config/.mocharc.js

@@ -33,7 +33,7 @@ module.exports = {
   parallel: false,
   recursive: false,
   reporter: 'spec',
-  'reporter-option': ['foo=bar', 'baz=quux'],
+  'reporter-option': ['foo=bar', 'baz=quux'], // array, not object
   require: '@babel/register',
   retries: 1,
   slow: '75',

example/config/.mocharc.yml

@@ -35,7 +35,7 @@ package: './package.json'
 parallel: false
 recursive: false
 reporter: 'spec'
-reporter-option:
+reporter-option: # array, not object
   - 'foo=bar'
   - 'baz=quux'
 require: '@babel/register'

lib/reporters/base.js

@@ -90,7 +90,7 @@ exports.colors = {
 
 exports.symbols = {
   ok: symbols.success,
-  err: symbols.err,
+  err: symbols.error,
   dot: '.',
   comma: ',',
   bang: '!'

lib/reporters/json.js

@@ -9,14 +9,14 @@
 var Base = require('./base');
 var fs = require('fs');
 var path = require('path');
-var errors = require('../errors');
-var createUnsupportedError = errors.createUnsupportedError;
+const createUnsupportedError = require('../errors').createUnsupportedError;
+const utils = require('../utils');
 var constants = require('../runner').constants;
 var EVENT_TEST_PASS = constants.EVENT_TEST_PASS;
+var EVENT_TEST_PENDING = constants.EVENT_TEST_PENDING;
 var EVENT_TEST_FAIL = constants.EVENT_TEST_FAIL;
 var EVENT_TEST_END = constants.EVENT_TEST_END;
 var EVENT_RUN_END = constants.EVENT_RUN_END;
-var EVENT_TEST_PENDING = constants.EVENT_TEST_PENDING;
 
 /**
  * Expose `JSON`.
@@ -34,7 +34,7 @@ exports = module.exports = JSONReporter;
  * @param {Runner} runner - Instance triggers reporter actions.
  * @param {Object} [options] - runner options
  */
-function JSONReporter(runner, options) {
+function JSONReporter(runner, options = {}) {
   Base.call(this, runner, options);
 
   var self = this;
@@ -44,11 +44,11 @@ function JSONReporter(runner, options) {
   var passes = [];
   var output;
 
-  if (options && options.reporterOptions && options.reporterOptions.output) {
-    if (!fs || !fs.writeFileSync) {
+  if (options.reporterOption && options.reporterOption.output) {
+    if (utils.isBrowser()) {
       throw createUnsupportedError('file output not supported in browser');
     }
-    output = options.reporterOptions.output;
+    output = options.reporterOption.output;
   }
 
   runner.on(EVENT_TEST_END, function(test) {
@@ -80,8 +80,15 @@ function JSONReporter(runner, options) {
 
     var json = JSON.stringify(obj, null, 2);
     if (output) {
-      fs.mkdirSync(path.dirname(output), {recursive: true});
-      fs.writeFileSync(output, json);
+      try {
+        fs.mkdirSync(path.dirname(output), {recursive: true});
+        fs.writeFileSync(output, json);
+      } catch (err) {
+        console.error(
+          `${Base.symbols.err} [mocha] writing output to "${output}" failed: ${err.message}\n`
+        );
+        process.stdout.write(json);
+      }
     } else {
       process.stdout.write(json);
     }

test/reporters/json.spec.js

@@ -3,6 +3,7 @@
 var fs = require('fs');
 var sinon = require('sinon');
 var JSONReporter = require('../../lib/reporters/json');
+var utils = require('../../lib/utils');
 var Mocha = require('../../');
 var Suite = Mocha.Suite;
 var Runner = Mocha.Runner;
@@ -98,6 +99,7 @@ describe('JSON reporter', function() {
       suite.addTest(test);
 
       runner.run(function(failureCount) {
+        sinon.restore();
         expect(runner, 'to satisfy', {
           testResults: {
             passes: [
@@ -150,11 +152,11 @@ describe('JSON reporter', function() {
     });
   });
 
-  describe("when 'reporterOptions.output' is provided", function() {
+  describe('when "reporterOption.output" is provided', function() {
     var expectedDirName = 'reports';
     var expectedFileName = 'reports/test-results.json';
     var options = {
-      reporterOptions: {
+      reporterOption: {
         output: expectedFileName
       }
     };
@@ -171,34 +173,61 @@ describe('JSON reporter', function() {
       suite.addTest(test);
     });
 
-    describe('when file can be created', function() {
-      it('should write test results to file', function(done) {
-        var fsMkdirSync = sinon.stub(fs, 'mkdirSync');
-        var fsWriteFileSync = sinon.stub(fs, 'writeFileSync');
+    it('should write test results to file', function(done) {
+      const fsMkdirSync = sinon.stub(fs, 'mkdirSync');
+      const fsWriteFileSync = sinon.stub(fs, 'writeFileSync');
 
-        fsWriteFileSync.callsFake(function(filename, content) {
-          var expectedJson = JSON.stringify(runner.testResults, null, 2);
-          expect(expectedFileName, 'to be', filename);
-          expect(content, 'to be', expectedJson);
-        });
+      fsWriteFileSync.callsFake(function(filename, content) {
+        const expectedJson = JSON.stringify(runner.testResults, null, 2);
+        expect(expectedFileName, 'to be', filename);
+        expect(content, 'to be', expectedJson);
+      });
 
-        runner.run(function() {
-          fsMkdirSync.calledWith(expectedDirName, {recursive: true});
-          expect(fsWriteFileSync.calledOnce, 'to be true');
-          done();
-        });
+      runner.run(function() {
+        expect(
+          fsMkdirSync.calledWith(expectedDirName, {recursive: true}),
+          'to be true'
+        );
+        expect(fsWriteFileSync.calledOnce, 'to be true');
+        done();
       });
     });
 
-    describe('when run in browser', function() {
-      it('should throw unsupported error', function() {
-        sinon.stub(fs, 'writeFileSync').value(false);
+    it('should warn and write test results to console', function(done) {
+      const fsMkdirSync = sinon.stub(fs, 'mkdirSync');
+      const fsWriteFileSync = sinon.stub(fs, 'writeFileSync');
+
+      fsWriteFileSync.throws('unable to write file');
+
+      const outLog = [];
+      const fake = chunk => outLog.push(chunk);
+      sinon.stub(process.stderr, 'write').callsFake(fake);
+      sinon.stub(process.stdout, 'write').callsFake(fake);
+
+      runner.run(function() {
+        sinon.restore();
+        expect(
+          fsMkdirSync.calledWith(expectedDirName, {recursive: true}),
+          'to be true'
+        );
+        expect(fsWriteFileSync.calledOnce, 'to be true');
         expect(
-          () => new JSONReporter(runner, options),
-          'to throw',
-          'file output not supported in browser'
+          outLog[0],
+          'to contain',
+          `[mocha] writing output to "${expectedFileName}" failed:`
         );
+        expect(outLog[1], 'to match', /"fullTitle": "JSON suite json test 1"/);
+        done();
       });
     });
+
+    it('should throw "unsupported error" in browser', function() {
+      sinon.stub(utils, 'isBrowser').callsFake(() => true);
+      expect(
+        () => new JSONReporter(runner, options),
+        'to throw',
+        'file output not supported in browser'
+      );
+    });
   });
 });