Testing Yeoman generator with bowerInstall and/or npmInstall - mocha.js

Question

I have a Yeoman generator that uses this.bowerInstall()
When I test it, it tries to install all the bower dependencies that I initialized this way. Is there a way to mock this function ?
The same goes for the this.npmInstall() function.

Answer 1

I eventually went with a different approach. The method from drorb's answer works if you are bootstrapping the test generators manually. If you use the RunContext based setup (as described on the Yeoman (testing page)[http://yeoman.io/authoring/testing.html]), the before block of the test looks something like this.
before(function (done) {
helpers.run(path.join( __dirname, '../app'))
.inDir(path.join( __dirname, './tmp')) // Clear the directory and set it as the CWD
.withOptions({ foo: 'bar' }) // Mock options passed in
.withArguments(['name-x']) // Mock the arguments
.withPrompt({ coffee: false }) // Mock the prompt answers
.on('ready', function (generator) {
// this is called right before `generator.run()`
})
.on('end', done);
})
You can add mock functions to the generator in the 'ready' callback, like so:
.on('ready', function(generator) {
generator.bowerInstall = function(args) {
// Do something when generator runs bower install
};
})
The other way is to include an option in the generator itself. Such as:
installAngular: function() {
if (!this.options['skip-install']) {
this.bowerInstall('angular', {
'save': true
});
}
}
finalInstall: function() {
this.installDependencies({
skipInstall: this.options['skip-install']
});
}
Now since you run the test with the 'skip-install' option, the dependencies are not installed. This has the added advantage of ensuring the command line skip-install argument works as expected. In the alternate case, even if you run the generator with the skip-install argument, the bowerInstall and npmInstall functions from your generator are executed even though, the installDependencies function is not (as it is usually configured as above)

Answer 2

Take a look at the tests for the Bootstrap generator, it contains an example of mocking the bowerInstall() function:
beforeEach(function (done) {
this.bowerInstallCalls = [];
// Mock bower install and track the function calls.
this.app.bowerInstall = function () {
this.bowerInstallCalls.push(arguments);
}.bind(this);
}.bind(this));