render_tests 0.1.0

A regression test framework for Dart.

render_tests

A regression test framework for Dart.

render_tests performs regression tests by comparing the rendered output against an expected output file. It also provides an easy way to create expected output files (called rebaselining).

Usage

Let's create regression tests for markdownToHtml function from markdown package.

The first thing you need to do is to implement Renderer<T> instance. render_tests uses it to generate an output from the given file. You can implement Renderer<T> by overriding render method with a call to markdownToHtml. Here, StringRenderer is a synonym for Renderer<String>.

class MarkdownRenderer implements StringRenderer {
  String render(String input) => markdownToHtml(input);
}

Once you have a Renderer<T>, you can construct a RendererTests instance from it. The second argument of the RendererTests is a glob pattern which specifies the input files. Let's grab every file with markdown extension.

Renderer<String> renderer = new MarkdownRenderer();
RendererTests tests = new RendererTests(renderer, '**.markdown');

If you run the test for the first time, you don't yet have the expected outputs to compare. You can create the expected outputs using rebaseline or rebaselineAll. If glob pattern matches foo.markdown, rebaselining will generate foo.markdown.expected file in the same directory as foo.markdown. Later, render_tests will use these expected outputs to find regression bugs. Don't forget to add these files to your VCS.

NOTE: render_tests does not provide a script to perform rebaselining because you need to create your own RendererTests instance with your custom Renderer<T>. I recommend you to create a small script which helps you perform rebaselining easily.

tests.rebaselineAll();

Now you are ready to perform regression tests. Let's assume you made a few changes to markdownToHtml function and want to make sure that it didn't introduce any regression bug. You can register tests using runTests functions. Just create a test group and call runTests in it. render_tests compares the rendered result with the expected output and check if they are still the same.

group('markdownToHtml tests', () {
  tests.runTests();
});

example/base64encoder_tests.dart is another example you can reference. The script provides commands to run tests and perform rebaselining.

base64encoder tests

Usage: base64encoder_tests <command> [arguments]

Global options:
-h, --help    Print this usage information.

Available commands:
  help         Display help information for base64encoder_tests.
  rebaseline   rebaseline the tests
  run          run the tests

Run "base64encoder_tests help <command>" for more information about a command.

Features and bugs

Please file feature requests and bugs at the issue tracker.