given_when_then

A Flutter package for creating more readable tests. If you are not familiar with Flutter's Widget tests please take a moment to review them.

Given we feel that our tests are the best documentation of the behaviors in our code.
When we read our tests.
Then we want them to be easy to understand.

Flutter widget tests are great but they can be a little verbose. The intention of this package is to enable code reuse while making our tests more readable. Consider this very simple widget test case from Flutter's Widget tests documentation.

Without given_when_then

testWidgets('MyWidget has a title and message', (WidgetTester tester) async {
    await tester.pumpWidget(MyWidget(title: 'T', message: 'M'));
    final titleFinder = find.text('T');
    final messageFinder = find.text('M');

    // Use the `findsOneWidget` matcher provided by flutter_test to verify
    // that the Text widgets appear exactly once in the widget tree.
    expect(titleFinder, findsOneWidget);
    expect(messageFinder, findsOneWidget);
});

With given_when_then

testWidgets('MyWidget has a title and message', harness((given, when, then) async {
    await given.pumpMyWidget(title: 'T', message: 'M');
    then.myTitleIs('T');
    then.myMessageIs('M');
  }));

As you can see, we are able to remove the details that are not important by moving them into the classes WidgetTestGiven, WidgetTestWhen, and WidgetTestThen.

For a complete example of how to use this please look at sample tests here: example_widget_test_support.dart

License Information

Copyright 2019-2020 eBay Inc.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  • Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
  • Neither the name of eBay Inc. nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Libraries

given_when_then