Testing

When testing commands, use the fake executor instead of the production executor. The production executor writes to stdout and stderr and manages process exit codes; the fake executor returns a MambaExecutionResult that you can assert against in tests.

A MambaSuccessResult is returned when a command produces output or null. A MambaFailureResult is returned when a command or hook throws an MambaException.

Write a test

Create a file in the test/ folder:

import 'package:mamba/mamba.dart';
import 'package:test/test.dart';

final class AddCommand extends Command {
  AddCommand() : super(mandatoryPositionals: [word]);

  static final word = NormalPositional('word');

  @override
  String get name => 'add';

  @override
  String get shortDescription => 'Add a word.';

  @override
  String run(CommandInvocation invocation, List<String> args) {
    final wordValue = invocation.valueOf(word);
    return 'Added $wordValue';
  }
}

void main() {
  test('add command succeeds', () async {
    final result = await Executor(
      'my-app',
      'This is my app.',
      '1.0.0',
      [AddCommand()],
    ).fake().execute(['add', 'something']);

    expect(result, isA<MambaSuccessResult>());
    expect((result as MambaSuccessResult).output, 'Added something');
  });
}

Triggering a failure

To trigger a failure, either:

1. Throw an MambaException from within run.
2. Pass an invalid value that the parser rejects, such as omitting a required input or supplying a value that fails validation.

Option 1: Throw an MambaException

@override
String run(CommandInvocation invocation, List<String> args) {
  throw MambaException('Something went wrong.');
}

Option 2: Trigger a parse error

Register a mandatory positional and invoke the command without it:

@override
String get name => 'add';

@override
String get shortDescription => 'Add a word.';

AddCommand() : super(mandatoryPositionals: [word]);

Running execute(['add']) without a word fails before run is called. The fake executor returns a MambaFailureResult whose exitCode and errors describe the parse failure.