dart-collect-coverage

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• Ignore a single line: // coverage:ignore-line

• Ignore a block of code: // coverage:ignore-start and // coverage:ignore-end

• Ignore an entire file: // coverage:ignore-file

Workflow: Configuring and Generating Coverage Reports

Follow this sequential workflow to add the coverage package, execute tests, and generate an LCOV report.

Task Progress Checklist:

• 1. Add coverage as a dev_dependency.

• 2. Execute the automated coverage script.

• 3. Validate the LCOV output.

1. Add Dependencies

Add the coverage package as a dev_dependency to your project. Do not add it to standard dependencies.

If working in a standard Dart project:

dart pub add dev:coverage

If working in a Flutter project:

flutter pub add dev:coverage

2. Collect Coverage and Generate LCOV

Use the bundled test_with_coverage script. This script automatically runs all tests, collects the JSON coverage data from the Dart VM, and formats it into an LCOV report.

dart run coverage:test_with_coverage

Note: If working within a Dart workspace (monorepo), specify the test directories explicitly (e.g., dart run coverage:test_with_coverage -- pkgs/foo/test pkgs/bar/test).

3. Feedback Loop: Validate Output

Run validator -> review errors -> fix:

• Verify that the coverage/ directory was created in the project root.

• Ensure coverage/coverage.json (raw data) and coverage/lcov.info (formatted report) exist.

• If coverage is missing for specific files, ensure they are imported and executed by your test files, or add // coverage:ignore-file if they are intentionally excluded.

Workflow: Advanced Manual Coverage Collection

If you require granular control over the VM service, isolate pausing, or need branch/function-level coverage, use the manual collection workflow.

Task Progress Checklist:

• 1. Run tests with VM service enabled.

• 2. Collect raw JSON coverage.

• 3. Format JSON to LCOV.

1. Run Tests with VM Service

Execute tests while pausing isolates on exit and exposing the VM service on a specific port (e.g., 8181).

dart run --pause-isolates-on-exit --disable-service-auth-codes --enable-vm-service=8181 test &

2. Collect Raw Coverage

Extract the coverage data from the running VM service and output it to a JSON file.

dart run coverage:collect_coverage --wait-paused --uri=http://127.0.0.1:8181/ -o coverage/coverage.json --resume-isolates

Optional: Append --function-coverage and --branch-coverage to gather deeper metrics (requires Dart VM 2.17.0+).

3. Format to LCOV

Convert the raw JSON data into the standard LCOV format.

dart run coverage:format_coverage --packages=.dart_tool/package_config.json --lcov -i coverage/coverage.json -o coverage/lcov.info --check-ignore

Examples

Example: pubspec.yaml Configuration

Ensure your pubspec.yaml reflects the coverage package strictly under dev_dependencies.

name: my_dart_app

environment:

  sdk: ^3.0.0

dependencies:

  path: ^1.8.0

dev_dependencies:

  test: ^1.24.0

  coverage: ^1.15.0

Example: Applying Ignore Directives

Use ignore directives to prevent generated code or untestable edge cases from lowering coverage scores.

// coverage:ignore-file

import 'package:meta/meta.dart';

class SystemConfig {

  final String env;

  SystemConfig(this.env);

  // coverage:ignore-start

  void legacyInit() {

    print('Deprecated initialization');

  }

  // coverage:ignore-end

  bool isProduction() {

    if (env == 'prod') return true;

    return false; // coverage:ignore-line

  }

}