Dart Test Fundamentals

Dart Test Fundamentals

When to use this skill

Use this skill when:

• Writing new test files.
• structuring test suites with group.
• Configuring test execution via dart_test.yaml.
• Understanding test lifecycle methods.

Core Concepts

1. Test Structure (test and group)

• test: The fundamental unit of testing.

``dart test('description', () { // assertions }); ``

• group: Used to organize tests into logical blocks.
• Groups can be nested.
• Descriptions are concatenated (e.g., "Group Description Test Description").
• Helps scope setUp and tearDown calls.
• Naming: Use PascalCase for groups that correspond to a class name

(e.g., group('MyClient', ...)).

• Avoid Single Groups: Do not wrap all tests in a file with a single

group call if it's the only one.

• Naming Tests:
• Avoid redundant "test" prefixes.
• Include the expected behavior or outcome in the description (e.g.,

'throws StateError' or 'adds API key to URL').

• Descriptions should read well when concatenated with their group name.

• Named Parameters Placement:
• For test and group calls, place named parameters (e.g., testOn,

timeout, skip) immediately after the description string, before the callback closure. This improves readability by keeping the test logic last. ``dart test('description', testOn: 'vm', () { // assertions }); ``

2. Lifecycle Methods (setUp, tearDown)

• setUp: Runs before every test in the current group (and nested

groups).

• tearDown: Runs after every test in the current group.
• setUpAll: Runs once before any test in the group.
• tearDownAll: Runs once after all tests in the group.

Best Practice:

• Use setUp for resetting state to ensure test isolation.
• Avoid sharing mutable state between tests without resetting it.

3. Configuration (dart_test.yaml)

The dart_test.yaml file configures the test runner. Common configurations include:

Platforms

Define where tests run (vm, chrome, node).

platforms:
  - vm
  - chrome

Tags

Categorize tests to run specific subsets.

tags:
  integration:
    timeout: 2x

Usage in code:

@Tags(['integration'])
import 'package:test/test.dart';

Running tags: dart test --tags integration

Timeouts

Set default timeouts for tests.

timeouts:
  2x # Double the default timeout

4. File Naming

• Test files must end in _test.dart to be picked up by the test runner.
• Place tests in the test/ directory.

Common commands

• dart test: Run all tests.
• dart test test/path/to/file_test.dart: Run a specific file.
• dart test --name "substring": Run tests matching a description.

Related Skills

dart-test-fundamentals is the core skill for structuring and configuring tests. For writing assertions within those tests, refer to:

• [dart-matcher-best-practices]:

Use this if the project sticks with the traditional package:matcher (expect calls).

• [dart-checks-migration]: Use this

if the project is migrating to the modern package:checks (check calls).

[dart-matcher-best-practices]: https://github.com/kevmoo/dashskills/blob/main/.agent/skills/dart-matcher-best-practices/SKILL.md [dart-checks-migration]: https://github.com/kevmoo/dashskills/blob/main/.agent/skills/dart-checks-migration/SKILL.md

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: mdazadhossain95
• Source: mdazadhossain95/flutter-agent-skills
• License: MIT

Install and usage instructions live in the source repository linked above.