Testing Classes with Service-Based Dependency Injection

<?php

namespace AKlump\PHPUnit\Test\EasyMock;

use AKlump\PHPUnit\EasyMock;
use AKlump\PHPUnit\EasyMockTrait;
use PHPUnit\Framework\TestCase;

Abstract Test Base Providing Services

To be able to provide class arguments based on service ids, you must implement getService in your test class (or abstract parent class), which hooks into your app's service container.

abstract class TestBase extends TestCase {

  use EasyMockTrait;

  static $lima, $november;

  /**
   * A contrived example of a service container retrieval.
   */
  public function getService($service_name) {
    switch ($service_name) {
      case 'my_app.lima':
        if (!static::$lima) {
          static::$lima = new Lima();
        }

        return static::$lima;

      case 'my_app.mike':
        // Non-shared: each call is a new instance.
        return new Mike();

      case 'my_app.november':
        if (!static::$november) {
          static::$november = new November();
        }

        return static::$november;
    }

    return NULL;
  }

}

Here is the Test

class ConstructorArgumentsUsingServiceIdsUnitTest extends TestBase {

  protected function getSchema() {
    return [
      'classToBeTested' => "AKlump\PHPUnit\Test\EasyMock\Kilo",

      // This is how we provide arguments to the class being tested using
      // service ids, in this example we have a service id 'my_app.lima'.
      // The order must match that of the constructor.
      'classArgumentsMap' => [

        'lima' => ['my_app.lima', EasyMock::SERVICE],

        // This is a shorthand form of the above; a string prefixed with '@'
        // means a shared service, where the id is 'my_app.november'.
        'november' => '@my_app.november',

        'mike' => ['my_app.mike', EasyMock::NON_SHARED_SERVICE],
      ],
    ];
  }

  public function testAbleToCallServiceMethodsAsExpectedViaDependencyGetter() {
    $this->assertSame('parrotlet', $this->obj->getLima()->getAnimal());
    $this->assertSame('zebra', $this->obj->getMike()->getAnimal());
    $this->assertSame('cat', $this->obj->getNovember()->getAnimal());
  }

  public function testConstructor() {

    // Use this assertion to quickly make sure constructor works as expected.
    $this->assertConstructorSetsInternalProperties();
  }

}

Class Being Tested

class Kilo {

  protected $lima, $mike, $november;

  public function __construct(Lima $lima, November $november, Mike $mike) {
    $this->lima = $lima;
    $this->mike = $mike;
    $this->november = $november;
  }

  public function getLima() {
    return $this->lima;
  }

  public function getMike() {
    return $this->mike;
  }

  public function getNovember() {
    return $this->november;
  }

}

Dependency Injected Service Classes

/**
 * Lima is registered in our app under the service id `my_app.lima`.
 */
class Lima {

  public function getAnimal() {
    return 'parrotlet';
  }

}

/**
 * November is registered in our app under the service id `my_app.november`.
 */
class November {

  public function getAnimal() {
    return 'cat';
  }

}

Dependency Injected Non-Shared Service Class

Learn more about non-shared services.

/**
 * Mike is registered in our app under the service id `my_app.mike`. It is a
 * non-shared service.
 */
class Mike {

  public function getAnimal() {
    return 'zebra';
  }

}