Guinness

Guinness is a port of the Jasmine library to Dart. It is inspired by the AngularDart implementation of Jasmine.

Installation

Add the Guinness dependency to your project’s pubspec.yaml.

dev_dependencies:
  guinness: ">=0.0.1 <1.0.0"

Then, run pub install.

Finally, import the guinness library.

import 'package:guinness/guinness.dart';

main() {
  //you specs
}

Or if you are testing a client-side application, and you want to use html matchers, import the guinness_html library.

import 'package:guinness/guinness_html.dart';

main() {
  guinnessEnableHtmlMatchers();
  //you specs
}

Syntax

Guinness specs are comprised of describe, it, beforeEach, and afterEach blocks.

import 'package:guinness/guinness.dart';

main(){
  describe("syntax", () {
    beforeEach(() {
      print("outer before");
    });

    afterEach(() {
      print("outer after");
    });

    it("runs first", () {
      print("first");
    });

    describe("nested describe", () {
      beforeEach(() {
        print("inner before");
      });

      afterEach(() {
        print("inner after");
      });

      it("runs second", () {
        print("second");
      });
    });
  });
}

This will print:

outer before, first, outer after
outer before, inner before, second, inner after, outer after
  • To exclude a describe, change it to xdescribe.
  • To exclude an it, change it to xit.
  • To make a describe exclusive, change it to ddescribe.
  • To make an it exclusive, change it to iit.

If there is an iit in your spec files, Guinness will run only iits. In this case ddescribes will be ignored.

Async

Since Dart has built-in futures, the Guinness framework makes a good use out of them. If you return a future from beforeEach, afterEach, or it, the framework will wait for that future to be resolved.

For instance:

beforeEach(connectToTheDatabase);

where connectToTheDatabase returns a future.

Similarly, you can write:

afterEach(releaseConnection);

You can also write async specs using the following technique:

it("should return an empty list when the database is empty", () {
  return queryDatabase().then((results){
    expect(results).toEqual([]);
  });
});

If a returned future gets rejected, the test fails.

Expect

They way you write assertions in Guinness is by using the expect function, as follows:

expect(2).toEqual(2);

These are a few examples:

expect(2).toEqual(2);
expect([1,2]).toContain(2);
expect(2).toBe(2);
expect(()=> throw "BOOM").toThrow();
expect(()=> throw "BOOM").toThrow("BOOM");
expect(false).toBeFalsy();
expect(null).toBeFalsy();
expect(true).toBeTruthy();
expect("any object").toBeTruthy();
expect("any object").toBeDefined();
expect(null).toBeNull();
expect("not null").toBeNotNull();

expect(2).not.toEqual(1);
expect([1,2]).not.toContain(3);
expect([1,2]).not.toBe([1,2]);
expect((){}).not.toThrow();
expect(null).not.toBeDefined();

expect(new DocumentFragment.html("<div>some html</div>"))
    .toHaveHtml("<div>some html</div>");

expect(new DocumentFragment.html("<div>some text</div>"))
    .toHaveText("some text");

expect(new DivElement()..classes.add('abc'))
    .toHaveClass("abc");

expect(new DivElement()..attributes['attr'] = 'value')
    .toHaveAttribute("attr");

expect(new DocumentFragment.html("<div>some html</div>"))
    .not.toHaveHtml("<div>some other html</div>");

expect(new DocumentFragment.html("<div>some text</div>"))
    .not.toHaveText("some other text");

expect(new DivElement()..classes.add('abc'))
    .not.toHaveClass("def");

expect(new DivElement()..attributes['attr'] = 'value')
    .not.toHaveAttribute("other-attr");

final select = new SelectElement();
select.children
  ..add(new OptionElement(value: "1"))
  ..add(new OptionElement(value: "2", selected: true))
  ..add(new OptionElement(value: "3"));
expect(select).toEqualSelect(["1", ["2"], "3"]);

You can also use unittest matchers, like this:

expect(myObject).to(beValid); //where beValid is a unittest matcher

Migrating from Unittest

To make migration from the unittest library to Guinness easier, expect supports an optional second argument.

expect(myObject, beValid); //same as expect(myObject).to(beValid);

This keeps your unittest assertions working, so you can change them one by one.

While transitioning you can have both the unittest and guinness libraries imported:

import 'package:unittest/unittest.dart' hide expect;
import 'package:guinness/guinness.dart';

Extending Guinness

If you are using a lot of custom matchers, and using expect(object).to(matcher) is tedious, you can extend the library, as follows:

library test_helper;

import 'guinness.dart' as gns;
export 'guinness.dart';

final _m = gns.guinness.matchers;

class CustomExpect extends gns.Expect {
  CustomExpect(actual) : super(actual);

  toBePositive() => _m.expect(actual > 0, true, reason: 'is not positive');
}

CustomExpect expect(actual) => new CustomExpect(actual);

Spy

Guinness supports Jasmine-like spy functions:

final s = guinness.createSpy("my spy");
expect(s).not.toHaveBeenCalled();

s(1);
expect(s).toHaveBeenCalled();
expect(s).toHaveBeenCalledOnce();
expect(s).toHaveBeenCalledWith(1);
expect(s).toHaveBeenCalledOnceWith(1);
expect(s).not.toHaveBeenCalledWith(2);

s(2);
expect((){
  expect(s).toHaveBeenCalledOnce();
}).toThrow();

expect((){
  expect(s).toHaveBeenCalledOnceWith(1);
}).toThrow();

You can also use the mock and dart_mocks libraries with it.

Guinness and Unittest

Guinness supports pluggable backends, but by default runs on top of the unittest library. Which means that if unittest.autoStart is set to true, your specs will run automatically.

You can always initialize specs manually:

guinness.initSpecs();

You can also run the specs, like this:

guinness.runSpecs();

Usually, you don't need to worry about it.

Guinness and Karma

Guinness works with Karma. Just configure karmaDartImports:

karmaDartImports: {
  guinness: 'package:guinness/guinness_html.dart'
}

Status

There are a few things that are still not supported (e.g., handling named parameters in expectations).

Implementation Details

Key Ideas

The main idea is to treat the Jasmine syntax as a domain specific language. Therefore, the implementation clearly separates such things as: syntax, semantic model, and execution model. Let's quickly look at the benefits this approach provides:

The semantic model is separate from the syntax.

The semantic model consists of It, Describe, Suite, BeforeEach, and AfterEach objects. You can create and analyse them without using the context-dependent nested Jasmine syntax.

The parsing of specs is separate from the execution of specs.

The library builds a tree of the It, Describe, Suite, BeforeEach, and AfterEach objects first. And after that, as a separate step, executes them. It enables all sorts of preprocessing (e.g., filtering, reordering).

Pluggable backends.

Since the library is a DSL, there can be multiple backend libraries actually executing the specs. By default, the library comes with the unittest backend.

Libraries

guinness
guinness_html