dars_test

Testing utilities and matchers for the dars package.

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Features

• Smart Result Matchers - isOk and isErr that automatically handle values, matchers, and predicates.
• Type-safe Verification - isOk<T>() and isErr<E>() for strict type checking.
• Rich Error Messages - Detailed mismatch descriptions including type information.
• Mockito Integration - whenResult and whenFutureResult helpers for stubbing Result-returning methods.

Installation

dev_dependencies:
  dars_test:

Usage

import 'package:dars/dars.dart';
import 'package:dars_test/dars_test.dart';
import 'package:test/test.dart';

void main() {
  test('example', () {
    final Result<int, String> result = Ok(42);

    // Basic variant check
    expect(result, isOk);

    // Value check
    expect(result, isOk(42));

    // Matcher check
    expect(result, isOk(greaterThan(0)));

    // Predicate check
    expect(result, isOk((v) => v % 2 == 0));

    // Type-safe check
    expect(result, isOk<int>(42));
  });
}

Example

See example/example.dart for more detailed examples.

Mockito Integration

dars_test provides utilities for stubbing methods that return Result types with Mockito.

Installation

Add mockito to your dev dependencies:

dev_dependencies:
  dars_test:
  mockito:
  build_runner:  # Required for @GenerateMocks

Usage

import 'package:dars/dars.dart';
import 'package:dars_test/mockito.dart';
import 'package:mockito/mockito.dart';

// For synchronous Result-returning methods
whenResult(
  () => mock.fetchData('123'),
  dummy: Ok('dummy'),
).thenReturn(Ok('Actual data'));

// For async Future<Result>-returning methods
whenFutureResult(
  () => mock.fetchDataAsync('456'),
  dummy: Ok('dummy'),
).thenAnswer((_) async => Ok('Actual async data'));

See example/mockito_example.dart for a complete example.

Error Messages

When a test fails, dars_test provides detailed information:

• Variant Mismatch: Expected: Ok but was: Err('timeout')
• Type Mismatch: Expected: Ok<int> but was: Ok<String>('42')
• Value Mismatch: Expected: Ok(42) but was: Ok(0)

License

BSD 3-Clause License