grunt-mocha-test

A grunt task for running server side mocha tests

Usage

Install next to your project's Gruntfile.js with:

npm install grunt-mocha-test --save-dev

Running tests

Here is a simple example gruntfile if you just want to run tests

module.exports = function(grunt) {

  // Add the grunt-mocha-test tasks.
  grunt.loadNpmTasks('grunt-mocha-test');

  grunt.initConfig({
    // Configure a mochaTest task
    mochaTest: {
      test: {
        options: {
          reporter: 'spec',
          captureFile: 'results.txt', // Optionally capture the reporter output to a file
          quiet: false, // Optionally suppress output to standard out (defaults to false)
          clearRequireCache: false, // Optionally clear the require cache before running tests (defaults to false)
          clearCacheFilter: (key) => true, // Optionally defines which files should keep in cache
          noFail: false // Optionally set to not fail on failed tests (will still fail on other errors)
        },
        src: ['test/**/*.js']
      }
    }
  });

  grunt.registerTask('default', 'mochaTest');

};

Options

The following options are specific to grunt-mocha-test (ie. not mocha options)

• captureFile - specify a file to capture all output to (will include any output from console.log)
• quiet - true to not output anything to console (normally used with the captureFile option when console output would not be human readable)
• clearRequireCache - true to clear the require cache before each test run (normally used with watch when not spawning each test run in a new nodejs context)
• clearCacheFilter - function() { return true/false } to say which files should remain in cache. Only works with clearRequireCache set to true)
• noFail - true to prevent the task failing on failed tests. Useful for CI setups where test reports are processed separately. Will still fail on other errors

The following mocha options have also been tested (others may have been added since the time of writing through changes to mocha)

• grep
• ui
• reporter
• timeout
• invert
• ignoreLeaks
• growl
• globals
• bail
• require
• slow

Specifying compilers

The Mocha --compilers option is almost identical to the --require option but with additional functionality for use with the Mocha --watch mode. As the --watch mode is not relevant for this plugin there is no need to implement a separate compilers option and actually the require option should be used instead.

The following example shows the use of the CoffeeScript compiler.

npm install coffee-script

mochaTest: {
  test: {
    options: {
      reporter: 'spec',
      require: 'coffee-script/register'
    },
    src: ['test/**/*.coffee']
  }
}

This is an example for the Babel 6 compiler (babel must be configured separately if you want to use it for something like ES6/ES2015).

npm install babel-register

mochaTest: {
  test: {
    options: {
      reporter: 'spec',
      require: 'babel-register'
    },
    src: ['test/**/*.js']
  }
}

In order to make this more user friendly, the require option can take either a single file/function or an array of files/functions in case you have other globals you wish to require.

eg.

mochaTest: {
  test: {
    options: {
      reporter: 'spec',
      require: [
        'coffee-script/register',
        './globals.js',
        function(){ testVar1=require('./stuff'); },
        function(){ testVar2='other-stuff'; }
      ]
    },
    src: ['test/**/*.coffee']
  }
}

NB. File references for the require option can only be used with Javascript files, ie. it is not possible to specify a ./globals.coffee in the above example.

Specifying a Mocha module

grunt-mocha-test uses npm's peerDependency functionality and thus uses whatever version of mocha is installed in your project. If your project does not have mocha installed, a compatible version will automatically be installed when adding grunt-mocha-test.

Generating coverage reports

Here is an example gruntfile that registers 2 test tasks, 1 to run the tests and 1 to generate a coverage report using blanket.js to instrument the javascript on the fly.

npm install blanket

module.exports = function(grunt) {

  grunt.loadNpmTasks('grunt-mocha-test');

  grunt.initConfig({
    mochaTest: {
      test: {
        options: {
          reporter: 'spec',
          // Require blanket wrapper here to instrument other required
          // files on the fly. 
          //
          // NB. We cannot require blanket directly as it
          // detects that we are not running mocha cli and loads differently.
          //
          // NNB. As mocha is 'clever' enough to only run the tests once for
          // each file the following coverage task does not actually run any
          // tests which is why the coverage instrumentation has to be done here
          require: 'coverage/blanket'
        },
        src: ['test/**/*.js']
      },
      coverage: {
        options: {
          reporter: 'html-cov',
          // use the quiet flag to suppress the mocha console output
          quiet: true,
          // specify a destination file to capture the mocha
          // output (the quiet option does not suppress this)
          captureFile: 'coverage.html'
        },
        src: ['test/**/*.js']
      }
    }
  });

  grunt.registerTask('default', 'mochaTest');
};

As noted above it is necessary to wrap the blanket require when calling mocha programatically so coverage/blanket.js should look something like this.

var path = require('path');
var srcDir = path.join(__dirname, '..', 'src');

require('blanket')({
  // Only files that match the pattern will be instrumented
  pattern: srcDir
});

This will preprocess all .js files in the src directory. Note that Blanket just uses pattern matching so this rework of the paths prevents files in node_modules being instrumented too. Also bear in mind using Blanket to instrument files on the fly only works if the file is not already in the require cache (this is an odd case but if you can't figure out why a file is not instrumented and the pattern looks ok then this may be the cause).

Failing tests if a coverage threshold is not reached

Building on the previous example, if you wish to have your tests fail if it falls below a certain coverage threshold then I advise using the travis-cov reporter

npm install travis-cov

module.exports = function(grunt) {

  grunt.loadNpmTasks('grunt-mocha-test');

  grunt.initConfig({
    mochaTest: {
      test: {
        options: {
          reporter: 'spec',
          require: 'coverage/blanket'
        },
        src: ['test/**/*.js']
      },
      'html-cov': {
        options: {
          reporter: 'html-cov',
          quiet: true,
          captureFile: 'coverage.html'
        },
        src: ['test/**/*.js']
      },
      // The travis-cov reporter will fail the tests if the
      // coverage falls below the threshold configured in package.json
      'travis-cov': {
        options: {
          reporter: 'travis-cov'
        },
        src: ['test/**/*.js']
      }
    }
  });

  grunt.registerTask('default', 'mochaTest');
};

Don't forget to update package.json with options for travis-cov, for example:

  ...

  "config": {
    "travis-cov": {
      // Yes, I like to set the coverage threshold to 100% ;)
      "threshold": 100
    }
  },

  ...

Instrumenting source files with coverage data before running tests

In most cases it may be more useful to instrument files before running tests. This has the added advantage of creating intermediate files that will match the line numbers reported in exception reports. Here is one possible Gruntfile.js that uses the grunt-blanket plug in.

npm install grunt-contrib-clean
npm install grunt-contrib-copy
npm install grunt-blanket
npm install travis-cov

module.exports = function(grunt) {

  grunt.loadNpmTasks('grunt-mocha-test');
  grunt.loadNpmTasks('grunt-contrib-clean');
  grunt.loadNpmTasks('grunt-contrib-copy');
  grunt.loadNpmTasks('grunt-blanket');

  grunt.initConfig({
    clean: {
      coverage: {
        src: ['coverage/']
      }
    },
    copy: {
      coverage: {
        src: ['test/**'],
        dest: 'coverage/'
      }
    },
    blanket: {
      coverage: {
        src: ['src/'],
        dest: 'coverage/src/'
      }
    },
    mochaTest: {
      test: {
        options: {
          reporter: 'spec',
        },
        src: ['/coverage/test/**/*.js']
      },
      coverage: {
        options: {
          reporter: 'html-cov',
          quiet: true,
          captureFile: 'coverage.html'
        },
        src: ['/coverage/test/**/*.js']
      },
      'travis-cov': {
        options: {
          reporter: 'travis-cov'
        },
        src: ['/coverage/test/**/*.js']
      }
    }
  });

  grunt.registerTask('default', ['clean', 'blanket', 'copy', 'mochaTest']);
};

This will delete any previously instrumented files, copy the test files to a coverage folder and instrument the src javascript files to the coverage folder. Lastly it runs tests from the coverage folder. It's more complicated but often easier to work with.

Running in permanent environments (like watch)

If you run grunt-mocha-test with grunt-contrib-watch using the spawn: false option, you will notice that the tests only run on the first change. Subsequent changes will result in an empty report with a 0 passing message.

This happens because mocha loads your tests using require resulting in them being added to the require cache. Thus once they have been loaded in a process the subsequent calls to require hit the cache without executing the code again. To prevent this from happening, use the clearRequireCache option (default value is false).

Here is an example that also demonstrates how to only run changed tests:

module.exports = function(grunt) {

  grunt.loadNpmTasks('grunt-mocha-test');
  grunt.loadNpmTasks('grunt-contrib-watch');

  grunt.initConfig({
    mochaTest: {
      test: {
        options: {
          reporter: 'spec',
          clearRequireCache: true
        },
        src: ['test/**/*.js']
      },
    },

    watch: {
      js: {
        options: {
          spawn: false,
        },
        files: '**/*.js',
        tasks: ['default']
      }
    }
  });

  // On watch events, if the changed file is a test file then configure mochaTest to only
  // run the tests from that file. Otherwise run all the tests
  var defaultTestSrc = grunt.config('mochaTest.test.src');
  grunt.event.on('watch', function(action, filepath) {
    grunt.config('mochaTest.test.src', defaultTestSrc);
    if (filepath.match('test/')) {
      grunt.config('mochaTest.test.src', filepath);
    }
  });

  grunt.registerTask('default', 'mochaTest');
};

Using node flags

There are some flags that Mocha supports that are actually Node flags, eg.

• --debug
• --harmony-generators

It is currently not possible to set these at runtime when using Mocha as a library and as such cannot be supported by grunt-mocha-test without a major refactor (and severe impact on performance as it would involve spawning processes).

The recommended way of using these flags would be to pass them to node when starting the grunt process. The simplest way to do this would be to leverage the scripts functionality of NPM and package.json.

  ...
  },
  "scripts": {
    "test": "node --debug --harmony-generators ./node_modules/.bin/grunt test"
  }
  ...

The tests would then be run using

npm test

Note that this assumes that grunt-cli has been installed locally and not globally

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using:

npm test

License

Copyright © 2016 Peter Halliday
Licensed under the MIT license.

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