How do I focus on one spec in jasmine.js?

Question

When using Karma, you can enable only one test with fit or fdescribe (iit and ddescribe in Jasmine before 2.1).

---

This only runs Spec1:

// or "ddescribe" in Jasmine prior 2.1
fdescribe('Spec1', function () {
    it('should do something', function () {
        // ...
    });
});

describe('Spec2', function () {
    it('should do something', function () {
        // ...
    });
});

---

This only runs testA:

describe('Spec1', function () {

    // or "iit" in Jasmine prior 2.1
    fit('testA', function () {
        // ...
    });

    it('testB', function () {
        // ...
    });

});

In core since 2.1 with fit and fdescribe.

You can run a single spec by using the url for the spec

describe("MySpec", function() { 
  it('function 1', function() { 
    //... 
  }) 

  it('function 2', function() { 
    //... 
  } 

}) 

Now you can run just the whole spec by this url http://localhost:8888?spec=MySpec and a the first test with http://localhost:8888?spec=MySpec+function+1

There are a few ways you can do it.

There is: Jasmine's feature Focused Specs (2.2): http://jasmine.github.io/2.2/focused_specs.html

Focusing specs will make it so that they are the only specs that run. Any spec declared with fit is focused.

describe("Focused specs", function() {
  fit("is focused and will run", function() {
    expect(true).toBeTruthy();
  });

  it('is not focused and will not run', function(){
    expect(true).toBeFalsy();
  });
});

However, I don't really like the idea of editing my tests (fit and fdescribe) to run them selectively. I prefer to use a test runner like karma which can filter out tests using a regular expression.

Here's an example using grunt.

$ grunt karma:dev watch --grep=mypattern

If you're using gulp (which is my favourite task runner), you can pass args into gulp-karma with yargs and match patterns by setting karma's config.

Kinda like this:

var Args = function(yargs) {
  var _match = yargs.m || yargs.match;
  var _file = yargs.f || yargs.file;
  return {
    match: function() { if (_match) { return {args: ['--grep', _match]} } }
  };
}(args.argv);


var Tasks = function() {
  var test = function() {
    return gulp.src(Files.testFiles)
      .pipe(karma({ configFile: 'karma.conf.js', client: Args.match()}))
      .on('error', function(err) { throw err; });
  };

  return {
    test: function() { return test() }
  }
}(Args);

gulp.task('default', ['build'], Tasks.test);

See my gist: https://gist.github.com/rimian/0f9b88266a0f63696f21

So now, I can run a single spec using the description:

My local test run: (Executed 1 of 14 (skipped 13))

gulp -m 'triggers the event when the API returns success'
[20:59:14] Using gulpfile ~/gulpfile.js
[20:59:14] Starting 'clean'...
[20:59:14] Finished 'clean' after 2.25 ms
[20:59:14] Starting 'build'...
[20:59:14] Finished 'build' after 17 ms
[20:59:14] Starting 'default'...
[20:59:14] Starting Karma server...
INFO [karma]: Karma v0.12.31 server started at http://localhost:9876/
INFO [launcher]: Starting browser Chrome
WARN [watcher]: All files matched by "/spec/karma.conf.js" were excluded.
INFO [Chrome 42.0.2311 (Mac OS X 10.10.3)]: Connected on socket hivjQFvQbPdNT5Hje2x2 with id 44705181
Chrome 42.0.2311 (Mac OS X 10.10.3): Executed 1 of 14 (skipped 13) SUCCESS (0.012 secs / 0.009 secs)
[20:59:16] Finished 'default' after 2.08 s

Also see: https://github.com/karma-runner/karma-jasmine

For anyone stumbling upon this, a better approach, which you can set up from the code itself, is to use this plugin: https://github.com/davemo/jasmine-only

It allows you set the spec exclusivity right on the code like this:

describe.only("MySpec", function() { 
  it('function 1', function() { 
    //... 
  }) 

  it.only('function 2', function() { 
    //... 
  }
})
// This won't be run if there are specs using describe.only/ddescribe or it.only/iit
describe("Spec 2", function(){}) 

There has been a long discussion to get this added to Jasmine core, see: https://github.com/pivotal/jasmine/pull/309

If you happen to be using Jasmine via Karma/Testacular you should already have access to ddescribe() and iit()

You can create your all your specs up front but disable them with xdescribe and xit until you're ready to test them.

describe('BuckRogers', function () {
  it('shoots aliens', function () {
    // this will be tested
  });

  xit('rescues women', function () {
    // this won't
  });
});

// this whole function will be ignored
xdescribe('Alien', function () {
  it('dies when shot', function () {
  });
});