The Dart unittest library allows you to run just a single test; to do so, just change the call for that test form test() to solo_test().

Another way to run a subset of your tests is by using the filterTests() function. filterTests() takes a String or a RegExp argument and matches it against each test description; if the description matches, the test runs, otherwise, it doesn’t.

Before you use filterTests(), you need to disable the automatic running of tests (set autoStart to false) and ensure that the your configuration is initialized.

You can do this by creating a custom configuration:

import "package:unittest/unittest.dart";
import "package:args/args.dart";

class FilterTests extends Configuration {
  get autoStart => false;
}

void useFilteredTests() {
  configure(new FilterTests());
  ensureInitialized();  
}

Then, you can call useFilteredTests() in your main(), define all your tests, call filteredTests() with a string or regexp argument and run your tests using runTests():

void main() {
  useFilteredTests();

  // your tests go here

  filterTests(some_string_or_regexp);
  runTests();
}

Here is a little working example:

void main() {
  useFilteredTests();

  test("one test", () {
    expect(1, equals(1));
  }); 

  test("another test", () {
    expect(2, equals(2));
  });

  test("and another", () {
    expect(3, equals(3));
  });

  filterTests('test');
  // filterTests('another');

  runTests();
}

filterTests('test') will run the first 2 tests; filterTests('another') will run the last 2 tests.

It is easy to make this considerably more useful by getting the argument to filterTests() from the command line. That way, you can control what subset of tests to run without having to change the code in your test suite. Here is a slightly expanded version of the same example:

void main() {
  useFilteredTests();
  ArgParser argParser = new ArgParser();
  Options options = new Options();
  ArgResults results = argParser.parse(options.arguments);
  List<String> args = results.rest; // get the args from the command line

  test("one test", (){
    expect(1, equals(1));
  }); 

  test("another test", (){
    expect(2, equals(2));
  });

  test("and another", (){
    expect(3, equals(3));
  });

  // we add a group() to show how we can easily run just the tests
  // contained in it
  group("foo", () {
    test("this", (){
      expect('bar', equals('bar'));
    }); 

    test("that", (){
      expect('baz', equals('baz'));
    });
  });

  if (!args.isEmpty) {
    filterTests(args[0]);
  }
  runTests();
}

You can run the tests from the command line by using the

`dart name_of_file.dart [keyword]`

syntax. If the keyword is this, only one test will run. If the keyword is foo, all tests in the group() with the description of foo will run. If you do not provide a keyword, all 5 tests will run.