Skip to main content

New setUp/tearDown in Unit Test library

Posted by Seth Ladd

Graham Wheeler, an engineer on the Dart project, announced today:


Our unit tests now support setUp/tearDown functions. To use these you need to put the tests within a group(). Inside the group body, in addition to calling test() you can call setUp() and/or tearDown() with function arguments. The setUp function will be called before each test and tearDown after each test.

Usually you would set these up at the start of the group:

group('foo', () {
  setUp(() {...});
  tearDown(() {...});
  test(description, () {...});
  ...
});

but you can interlace them differently; each test() will use the most recently set values setUp/tearDown.

Whenever a new group is started these are reset. This applies for nested groups too. Nested groups do not inherit these functions or augment them; they get their own. This seemed the most flexible approach as chaining can always be done explicitly.

Another new (unrelated) change is that you can now pass a --filter=<string> argument to test.py. Only tests whose descriptions match the supplied string will be executed. The string gets wrapped in a RegExp so you can use flexible matching. This can be combined with other restrictions, so for example I could use:

tools/test.py --compiler=none --runtime=vm --filter=contains lib/unittest

to run all the tests in lib/unittest/test*.dart that have descriptions containing the word contains.

As always, you can join the Dart mailing list to send along your feedback. Thanks for trying Dart!

Popular posts from this blog

AngularDart 4

AngularDart v4 is now available. We've been busy since the release angular2 v3.1.0 in May. Not only did we "drop the 2", but we also improved the compiler and tightened up the framework to give you smaller code, we updated the package structure to improve usability, and we added several new features. Check out the updated documentation to get started.
Just angular Upgrading to v4 will require more than updating your version constraint. The package has changed names (back) to angular – dropping the 2. You'll need to update your pubspec.yaml and the corresponding imports in your code. In most instances, find-and-replace should do the trick. Going forward, the package will be called package:angular. We'll just update the version number.
Smaller code The updated compiler in 4.0 allows type-based optimizations that not only improve runtime performance but generate better code because we are able to strongly type templates. A big result of the update is that many ap…

The new AdWords UI uses Dart — we asked why

Google just announced a re-designed AdWords experience. In case you’re not familiar with AdWords: businesses use it to advertise on google.com and partner websites. Advertising makes up majority of Google’s revenue, so when Google decides to completely redo the customer-facing front end to it, it’s a big deal. The Dart team is proud to say that this new front end is built with Dart and Angular 2. Whenever you asked us whether Google is ‘even using Dart for anything,’ this is what we had in mind but couldn’t say aloud. Until now. We asked Joshy Joseph, the primary technical lead on the project, some questions. Joshy is focusing on things like infrastructure, application latency and development velocity, so he’s the right person to ask about Dart.Q: What exactly did we launch on Monday?It’s a complete redesign of the AdWords customer experience that is rolling out slowly as a test to a small initial set of advertisers. The most noticeable thing is probably the Material Design look and f…

Const, Static, Final, Oh my!

Posted by Seth Ladd

(This is an "oldie but a goodie" misc@dartlang.org post originally written by Bob Nystrom. It is being posted here as the explanations still ring true.)

Bob writes:


"static", "final", and "const" mean entirely distinct things in Dart:

"static" means a member is available on the class itself instead of on instances of the class. That's all it means, and it isn't used for anything else. static modifies *members*.

"final" means single-assignment: a final variable or field *must* have an initializer. Once assigned a value, a final variable's value cannot be changed. final modifies *variables*.

"const" has a meaning that's a bit more complex and subtle in Dart. const modifies *values*. You can use it when creating collections, like const [1, 2, 3], and when constructing objects (instead of new) like const Point(2, 3). Here, const means that the object's entire deep state can be determ…