feat: LDP-1689: Add database connection trait. (#23)

* feat: LDP-1689: Add database connection trait.

* LDP-1689: Fix phpcs errors.

* test: LDP-1689: Add tests for database connection trait.

* LDP-1689: Improve test for watchdog errors.

src/Core/Database/DatabaseConnectionTrait.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace drunomics\ServiceUtils\Core\Database;
+
+use Drupal\Core\Database\Connection;
+
+/**
+ * Allows setter injection and simple usage of the service.
+ */
+trait DatabaseConnectionTrait {
+
+  /**
+   * The database connection service.
+   *
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $connection;
+
+  /**
+   * Sets database connection.
+   *
+   * @param \Drupal\Core\Database\Connection $connection
+   *   The database connection service.
+   *
+   * @return \Drupal\Core\Database\Connection
+   */
+  public function setDatabaseConnection(Connection $connection) {
+    $this->connection = $connection;
+    return $this;
+  }
+
+  /**
+   * Gets database connection service.
+   *
+   * @return \Drupal\Core\Database\Connection
+   *   The database connection service.
+   */
+  public function getDatabaseConnection() {
+    if (empty($this->connection)) {
+      $this->connection = \Drupal::service('database');
+    }
+    return $this->connection;
+  }
+
+}

tests/src/Core/Database/DatabaseConnectionTraitTest.php

@@ -0,0 +1,73 @@
+<?php
+
+namespace drunomics\ServiceUtils\Tests\Core\Database;
+
+use drunomics\ServiceUtils\Core\Database\DatabaseConnectionTrait;
+use Drupal\Core\DependencyInjection\Container;
+use Drupal\Core\Database\Connection;
+use PHPUnit\Framework\TestCase;
+use Prophecy\PhpUnit\ProphecyTrait;
+
+/**
+ * @coversDefaultClass \drunomics\ServiceUtils\Core\Database\DatabaseConnectionTrait
+ * @group ServiceUtils
+ */
+class DatabaseConnectionTraitTest extends TestCase {
+
+  use DatabaseConnectionTrait;
+  use ProphecyTrait;
+
+  /**
+   * The id of the trait's service.
+   *
+   * @var string
+   */
+  protected $serviceId = 'database';
+
+  /**
+   * @covers ::getDatabaseConnection
+   */
+  public function testGetter() {
+    // Verify the container is used once and the right service is returned.
+    $service = $this->mockContainerWithFakeService(['calls' => 1]);
+    $this->assertsame($service, $this->getDatabaseConnection());
+    // Multiple calls should fetch the service from the container only once.
+    $this->getDatabaseConnection();
+  }
+
+  /**
+   * @covers ::setDatabaseConnection
+   */
+  public function testSetter() {
+    // Verify the set service is returned.
+    $this->mockContainerWithFakeService(['calls' => 0]);
+    $service = $this->prophesize()
+      ->willExtend(Connection::class)
+      ->reveal();
+    $this->setDatabaseConnection($service);
+    $this->assertsame($service, $this->getDatabaseConnection());
+  }
+
+  /**
+   * Helper to mock the container with a stub service.
+   *
+   * @param int[] $options
+   *   An array with the following keys:
+   *   - calls: The number of calls to get the service the mocked container
+   *     expects.
+   *
+   * @return object
+   *   The fake service returned by the container.
+   */
+  protected function mockContainerWithFakeService(array $options) {
+    $service = new \Stdclass();
+    $container = $this->prophesize(Container::class);
+    $prophecy = $container->get($this->serviceId);
+    /** @var \Prophecy\Prophecy\MethodProphecy $prophecy */
+    $prophecy->shouldBeCalledTimes($options['calls']);
+    $prophecy->willReturn($service);
+    \Drupal::setContainer($container->reveal());
+    return $service;
+  }
+
+}