karma-ng-html2js-preprocessor

> Preprocessor for converting HTML files to AngularJS 1.x and Angular 2 templates.

Note: If you are looking for a general preprocessor that is not tied to Angular, check out karma-html2js-preprocessor.

Installation

The easiest way is to keep karma-ng-html2js-preprocessor as a devDependency in your package.json. Just run

$ npm install karma-ng-html2js-preprocessor --save-dev

Configuration

// karma.conf.js
module.exports = function(config) {
  config.set({
    preprocessors: {
      '**/*.html': ['ng-html2js']
    },

    files: [
      '*.js',
      '*.html',
      '*.html.ext',
      // if you wanna load template files in nested directories, you must use this
      '**/*.html'
    ],

    // if you have defined plugins explicitly, add karma-ng-html2js-preprocessor
    // plugins: [
    //     
    //     'karma-ng-html2js-preprocessor',
    // ]

    ngHtml2JsPreprocessor: {
      // strip this from the file path
      stripPrefix: 'public/',
      stripSuffix: '.ext',
      // prepend this to the
      prependPrefix: 'served/',

      // or define a custom transform function
      // - cacheId returned is used to load template
      //   module(cacheId) will return template at filepath
      cacheIdFromPath: function(filepath) {
        // example strips 'public/' from anywhere in the path
        // module(app/templates/template.html) => app/public/templates/template.html
        var cacheId = filepath.strip('public/', '');
        return cacheId;
      },

      // - setting this option will create only a single module that contains templates
      //   from all the files, so you can load them all with module('foo')
      // - you may provide a function(htmlPath, originalPath) instead of a string
      //   if you'd like to generate modules dynamically
      //   htmlPath is a originalPath stripped and/or prepended
      //   with all provided suffixes and prefixes
      moduleName: 'foo'
    }
  })
}

Multiple module names

Use function if more than one module that contains templates is required.

// karma.conf.js
module.exports = function(config) {
  config.set({
    // ...

    ngHtml2JsPreprocessor: {
      // ...

      moduleName: function (htmlPath, originalPath) {
        return htmlPath.split('/')[0];
      }
    }
  })
}

If only some of the templates should be placed in the modules, return '', null or undefined for those which should not.

// karma.conf.js
module.exports = function(config) {
  config.set({
    // ...

    ngHtml2JsPreprocessor: {
      // ...

      moduleName: function (htmlPath, originalPath) {
        var module = htmlPath.split('/')[0];
        return module !== 'tpl' ? module : null;
      }
    }
  })
}

How does it work ?

This preprocessor converts HTML files into JS strings and generates Angular modules. These modules, when loaded, puts these HTML files into the $templateCache and therefore Angular won't try to fetch them from the server.

For instance this template.html...

<div>something</div>

... will be served as template.html.js:

angular.module('template.html', []).run(function($templateCache) {
  $templateCache.put('template.html', '<div>something</div>')
})

See the ng-directive-testing for a complete example.

Angular2 template caching

For using this preprocessor with Angular 2 templates use angular: 2 option in the config file.

// karma.conf.js
module.exports = function(config) {
  config.set({
    // ...

    ngHtml2JsPreprocessor: {
      // ...

      angular: 2
    }
  })
}

The template template.html...

<div>something</div>

... will be served as template.html.js that sets the template content in the global $templateCache variable:

window.$templateCache = window.$templateCache || {}
window.$templateCache['template.html'] = '<div>something</div>';

To use the cached templates in your Angular 2 tests use the provider for the Cached XHR implementation - CACHED_TEMPLATE_PROVIDER from angular2/platform/testing/browser. The following shows the change in karma-test-shim.js to use the cached XHR and template cache in all your tests.

// karma-test-shim.js
...
System.import('angular2/testing').then(function(testing) {
  return System.import('angular2/platform/testing/browser').then(function(providers) {
    testing.setBaseTestProviders(
      providers.TEST_BROWSER_PLATFORM_PROVIDERS,
      [providers.TEST_BROWSER_APPLICATION_PROVIDERS, providers.CACHED_TEMPLATE_PROVIDER]);
  });
}).then(function() {
...

Now when your component under test uses template.html in its templateUrl the contents of the template will be used from the template cache instead of making a XHR to fetch the contents of the template. This can be useful while writing fakeAsync tests where the component can be loaded synchronously without the need to make a XHR to get the templates.

For more information on Karma see the homepage.