oliverdavies.uk/content/node.077780fd-8480-426c-80b9-d54befef06b1.json

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    "title": [
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            "value": "Avoiding over-mocking\n"
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            "value": "\n          <p>In unit tests, and sometimes in kernel tests, you need to mock the dependencies you aren't testing, but you can over-mock and only be testing the mocks and not the code you want to test.<\/p>\n\n<p>Here's an example (thanks, ChatGPT, for the code).<\/p>\n\n<h2 id=\"the-class-to-be-tested-myclass.php\">The Class to be tested (MyClass.php)<\/h2>\n\n<pre><code class=\"language-php\">&lt;?php\n\nclass MyClass {\n\n  public function __construct(\n    private DependencyInterface $dependency\n  ) {\n  }\n\n  public function doSomething() {\n    $result = $this-&gt;dependency-&gt;performAction();\n\n    return \"Result: \" . $result;\n  }\n}\n<\/code><\/pre>\n\n<h2 id=\"dependency-interface-dependencyinterface.php\">Dependency Interface (DependencyInterface.php)<\/h2>\n\n<pre><code class=\"language-php\">&lt;?php\n\ninterface DependencyInterface {\n\n  public function performAction();\n\n}\n<\/code><\/pre>\n\n<h2 id=\"a-test-class-that-ends-up-testing-mocks-myclasstest.php\">A test class that ends up testing mocks (MyClassTest.php)<\/h2>\n\n<pre><code class=\"language-php\">&lt;?php\n\nuse PHPUnit\\Framework\\TestCase;\n\nclass MyClassTest extends TestCase {\n\n  public function testDoSomething() {\n    \/\/ Creating a mock of the DependencyInterface.\n    $dependencyMock = $this-&gt;createMock(DependencyInterface::class);\n\n    \/\/ Setting up the mock to return a specific value.\n    $dependencyMock-&gt;expects($this-&gt;once())\n      -&gt;method('performAction')\n      -&gt;willReturn('Mocked result');\n\n    \/\/ Creating an instance of MyClass with the mock.\n    $myClass = new MyClass($dependencyMock);\n\n    \/\/ Calling the method to be tested.\n    $result = $myClass-&gt;doSomething();\n\n    \/\/ Asserting that the result matches the expected value.\n    $this-&gt;assertEquals('Result: Mocked result', $result);\n  }\n\n}\n<\/code><\/pre>\n\n<h2 id=\"here%27s-the-thing\">Here's the thing<\/h2>\n\n<p>In this example, the test creates a mock for the <code>DependencyInterface<\/code> and sets up an expectation that the performAction method will be called once, returning a specific value.<\/p>\n\n<p>The test then calls the <code>doSomething<\/code> method on <code>MyClass<\/code> and asserts that the result is as expected.<\/p>\n\n<p>The issue with this test is that it's not testing the actual behaviour of <code>MyClass<\/code>.<\/p>\n\n<p>It's only testing that the mock is configured correctly.<\/p>\n\n<p>If the real implementation of <code>MyClass<\/code> has a bug, this test won't catch it.<\/p>\n\n        ",
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            "processed": "\n          <p>In unit tests, and sometimes in kernel tests, you need to mock the dependencies you aren't testing, but you can over-mock and only be testing the mocks and not the code you want to test.<\/p>\n\n<p>Here's an example (thanks, ChatGPT, for the code).<\/p>\n\n<h2 id=\"the-class-to-be-tested-myclass.php\">The Class to be tested (MyClass.php)<\/h2>\n\n<pre><code class=\"language-php\">&lt;?php\n\nclass MyClass {\n\n  public function __construct(\n    private DependencyInterface $dependency\n  ) {\n  }\n\n  public function doSomething() {\n    $result = $this-&gt;dependency-&gt;performAction();\n\n    return \"Result: \" . $result;\n  }\n}\n<\/code><\/pre>\n\n<h2 id=\"dependency-interface-dependencyinterface.php\">Dependency Interface (DependencyInterface.php)<\/h2>\n\n<pre><code class=\"language-php\">&lt;?php\n\ninterface DependencyInterface {\n\n  public function performAction();\n\n}\n<\/code><\/pre>\n\n<h2 id=\"a-test-class-that-ends-up-testing-mocks-myclasstest.php\">A test class that ends up testing mocks (MyClassTest.php)<\/h2>\n\n<pre><code class=\"language-php\">&lt;?php\n\nuse PHPUnit\\Framework\\TestCase;\n\nclass MyClassTest extends TestCase {\n\n  public function testDoSomething() {\n    \/\/ Creating a mock of the DependencyInterface.\n    $dependencyMock = $this-&gt;createMock(DependencyInterface::class);\n\n    \/\/ Setting up the mock to return a specific value.\n    $dependencyMock-&gt;expects($this-&gt;once())\n      -&gt;method('performAction')\n      -&gt;willReturn('Mocked result');\n\n    \/\/ Creating an instance of MyClass with the mock.\n    $myClass = new MyClass($dependencyMock);\n\n    \/\/ Calling the method to be tested.\n    $result = $myClass-&gt;doSomething();\n\n    \/\/ Asserting that the result matches the expected value.\n    $this-&gt;assertEquals('Result: Mocked result', $result);\n  }\n\n}\n<\/code><\/pre>\n\n<h2 id=\"here%27s-the-thing\">Here's the thing<\/h2>\n\n<p>In this example, the test creates a mock for the <code>DependencyInterface<\/code> and sets up an expectation that the performAction method will be called once, returning a specific value.<\/p>\n\n<p>The test then calls the <code>doSomething<\/code> method on <code>MyClass<\/code> and asserts that the result is as expected.<\/p>\n\n<p>The issue with this test is that it's not testing the actual behaviour of <code>MyClass<\/code>.<\/p>\n\n<p>It's only testing that the mock is configured correctly.<\/p>\n\n<p>If the real implementation of <code>MyClass<\/code> has a bug, this test won't catch it.<\/p>\n\n        ",
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