Issue #3315119 by Murz: Implement a getter for mocked method in MockObject

src/UnitTestHelpers.php

@@ -12,6 +12,8 @@ use Drupal\Core\Entity\Query\ConditionInterface as EntityQueryConditionInterface
 use Drupal\test_helpers\Stub\ModuleHandlerStub;
 use Drupal\test_helpers\Stub\TokenStub;
 use PHPUnit\Framework\Assert;
+use PHPUnit\Framework\MockObject\Builder\InvocationMocker;
+use PHPUnit\Framework\MockObject\MethodNameNotConfiguredException;
 use PHPUnit\Framework\MockObject\MockObject;
 use Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException;
 use Symfony\Component\Yaml\Yaml;
@@ -63,6 +65,32 @@ class UnitTestHelpers {
     return $property->getValue($class);
   }
 
+  /**
+   * Gets a mocked method from the Mock object to replace return value.
+   *
+   * This allows to replace the return value of the already defined method via
+   * `$mockedMethod->willReturn('New Value')`.
+   *
+   * It's not possible with PHPUnit API, but here is a feature request about it:
+   * https://github.com/sebastianbergmann/phpunit/issues/5070 - please vote!
+   */
+  public static function getMockedMethod(MockObject $mock, string $method) {
+    $invocationHandler = $mock->__phpunit_getInvocationHandler();
+    $configurableMethods = self::getProtectedProperty($invocationHandler, 'configurableMethods');
+    $matchers = self::getProtectedProperty($invocationHandler, 'matchers');
+    foreach ($matchers as $matcher) {
+      $methodNameRuleObject = self::getProtectedProperty($matcher, 'methodNameRule');
+      if ($methodNameRuleObject->matchesName($method)) {
+        return new InvocationMocker(
+            $invocationHandler,
+            $matcher,
+            ...$configurableMethods
+        );
+      }
+    }
+    throw new MethodNameNotConfiguredException();
+  }
+
   /**
    * Parses the annotation for a class and gets the definition.
    */

tests/src/Unit/UnitTestHelpersTest.php

+<?php
+
+namespace Drupal\Tests\test_helpers\Unit;
+
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\test_helpers\UnitTestHelpers;
+use Drupal\Tests\UnitTestCase;
+use PHPUnit\Framework\MockObject\MethodNameAlreadyConfiguredException;
+
+/**
+ * Tests UnitTestHelpers functions.
+ *
+ * @coversDefaultClass \Drupal\test_helpers\UnitTestHelpers
+ * @group test_helpers
+ */
+class UnitTestHelpersTest extends UnitTestCase {
+
+  /**
+   * @covers ::getMockedMethod
+   */
+  public function testGetMockedMethod() {
+    $mock = $this->createMock(EntityInterface::class);
+    $mock->method('label')->willReturn('foo');
+    $mock->method('id')->willReturn('42');
+    $this->assertEquals('foo', $mock->label());
+
+    // Ensuring that default overriding is not yet available.
+    try {
+      $mock->method('label')->willReturn('bar');
+    }
+    catch (MethodNameAlreadyConfiguredException $e) {
+      $this->assertInstanceOf(MethodNameAlreadyConfiguredException::class, $e);
+    }
+    $this->assertNotEquals('bar', $mock->label());
+
+    // Testing custom overriding of the method return value.
+    $labelMethod = UnitTestHelpers::getMockedMethod($mock, 'label');
+    $labelMethod->willReturn('baz');
+    $mock->method('uuid')->willReturn('myUUID');
+    $this->assertEquals('baz', $mock->label());
+    $this->assertNotEquals('foo', $mock->label());
+    $this->assertEquals('42', $mock->id());
+    $this->assertEquals('myUUID', $mock->uuid());
+
+    // Testing the second overriding of the method return value.
+    $labelMethod->willReturn('qux');
+    $this->assertEquals('qux', $mock->label());
+
+    // Testing a next getter and overriding of the method return value.
+    $labelMethod2 = UnitTestHelpers::getMockedMethod($mock, 'label');
+    $labelMethod2->willReturnArgument(1);
+    $this->assertEquals('arg1', $mock->label('arg0', 'arg1'));
+
+    // Testing a getter with callback function
+    $idMethod = UnitTestHelpers::getMockedMethod($mock, 'id');
+    $idMethod->willReturnCallback(function () {
+      return 777;
+    });
+    $this->assertSame(777, $mock->id());
+  }
+
+}