In PHP development, testing is a very important link. Testing can greatly reduce the occurrence of errors and improve code quality. Mock testing is a form of testing that can simulate fake objects or data in order to test a specific function or scenario of our code.

PHPUnit is a very popular testing framework in PHP, which supports Mock testing. In this article, we will explore how to use PHPUnit for mock testing.

1. What is Mock testing

Before we begin, let’s first understand the concept of Mock testing. Mock testing is a type of simulation test that allows us to test without real dependencies.

For example, we are developing an e-commerce website that includes a shopping cart functionality. When conducting shopping cart testing, we need to test functions such as adding, deleting, and price calculations for items. However, these features may rely on other modules or external APIs. This makes our testing very difficult. If we need to conduct real testing, the testing cost will be very high.

Mock testing allows us to test without real dependencies. In the shopping cart test, we can use the Mock testing framework to create a mock product and use it in the test to test the addition, deletion, price calculation and other functions of the product. This way we can easily test the functionality of the shopping cart without requiring real items or an external API.

2. Use PHPUnit for Mock testing

Next, we will use the PHPUnit testing framework for Mock testing. In PHPUnit, we can use the PHPUnitFrameworkMockObjectMockBuilder class to create Mock objects. MockBuilder is a class in PHPUnit that can help us create Mock objects.

1. Create Mock objects

In PHPUnit, we can use MockBuilder to create Mock objects. We can create a mock object through MockBuilder and define its methods and properties. We can then use the Mock object to test our code.

For example, we need to simulate a product object in the shopping cart test. We can use MockBuilder to create a mock commodity object.

Code example:

use PHPUnitFrameworkTestCase;

class ShoppingCartTest extends TestCase
{
    public function testAddProduct()
    {
        // 創(chuàng)建 MockBuilder 對(duì)象
        $product = $this->getMockBuilder(Product::class)
            ->getMock();

        // 測(cè)試真實(shí)代碼，使用假對(duì)象
        $cart = new ShoppingCart();
        $cart->addProduct($product);

        // 斷言購(gòu)物車(chē)中包含模擬的商品
        $this->assertTrue($cart->hasProduct($product));
    }
}

In this example code, we create a MockBuilder object to build a simulated product object (Product). Then, we use this object to perform the add product function of the shopping cart. Finally, we used the assertTrue() assertion to verify whether the shopping cart contains the product object we constructed.

2. Method definition and return value setting

We can simulate real objects or data by setting the methods and properties of the Mock object.

For example, we have a Person class, which has a sayHello() method, which can return a string "Hello".

Code example:

class Person {
    public function sayHello() {
        return "Hello";
    }
}

Now, we have a Greeting class whose method depends on the sayHello() method of the Person class. We can use MockBuilder to create a mock Person object and call the Greeting method in the test.

Code example:

use PHPUnitFrameworkTestCase;

class GreetingTest extends TestCase
{
    public function testSayHello()
    {
        // 創(chuàng)建 MockBuilder 對(duì)象
        $person = $this->getMockBuilder(Person::class)
            ->getMock();

        // 定義方法返回值
        $person->expects($this->any())
            ->method('sayHello')
            ->willReturn('Hello, Mock');

        // 測(cè)試真實(shí)代碼，使用假對(duì)象
        $greeting = new Greeting($person);
        $this->assertEquals('Hello, Mock', $greeting->sayHello());
    }
}

In this example code, we create a MockBuilder object to build a mock Person object. Then, we define the return value of the sayHello() method of the Person object as "Hello, Mock". Finally, we used the object to execute Greeting's sayHello() method, and used assertEquals() to assert whether the method returned "Hello, Mock".

3. Method call verification

In PHPUnit, we can use Mock objects to verify method calls. We can use PHPUnit's expectations API to verify that the method was called.

For example, we have a Person class, which has a sayHello() method, which returns a string "Hello".

Code example:

class Person {
    public function sayHello() {
        return "Hello";
    }
}

Now, we have a Greeting class whose constructor requires a Person object and has a sayHello() method that depends on the SayHello() method of the Person class. We can use the expectations API to test whether the sayHello() method of the greeting class successfully calls the sayHello() method of the Person class.

Code example:

use PHPUnitFrameworkTestCase;

class GreetingTest extends TestCase
{
    public function testSayHello()
    {
        // 創(chuàng)建 MockBuilder 對(duì)象
        $person = $this->getMockBuilder(Person::class)
            ->getMock();

        // 驗(yàn)證方法是否被調(diào)用
        $person->expects($this->once())
            ->method('sayHello');

        // 測(cè)試真實(shí)代碼，使用假對(duì)象
        $greeting = new Greeting($person);
        $greeting->sayHello();
    }
}

In this example code, we create a MockBuilder object to build a mock Person object. We then use the expectations API to verify whether the sayHello() method of the Person class was successfully called.

4. Mock test of constructor

In PHPUnit, we can use the getMock() method to simulate the instantiation process of a class and set the constructor and constructor parameters respectively.

For example, we have a Calculator class that has a constructor and an add method. In the constructor, we need to pass a number $a and $b. The add method adds a and b and returns the result.

Code Example:

class Calculator
{
    public function __construct($a, $b)
    {
        $this->a = $a;
        $this->b = $b;
    }

    public function add()
    {
        return $this->a + $this->b;
    }
}

Now, we have a CalculatorTest class that needs to test the add method of the Calculator class. We can use the getMock() method to simulate the creation process of the Calculator object and set the parameters of the constructor.

Code example:

use PHPUnitFrameworkTestCase;

class CalculatorTest extends TestCase
{
    public function testAdd()
    {
        // 創(chuàng)建 Mock 對(duì)象
        $calculator = $this->getMockBuilder(Calculator::class)
            ->disableOriginalConstructor()
            ->getMock();

        // 手動(dòng)設(shè)置構(gòu)造函數(shù)參數(shù)
        $calculator->expects($this->any())
            ->method('__construct')
            ->with(2, 3)
            ->willReturn(5);

        // 測(cè)試真實(shí)代碼，使用假對(duì)象
        $this->assertEquals(5, $calculator->add());
    }
}

在這個(gè)示例代碼中，我們創(chuàng)建了一個(gè)MockBuilder對(duì)象來(lái)構(gòu)建一個(gè)模擬Calculator對(duì)象。然后，我們使用getMock()方法來(lái)模擬Calculator對(duì)象的創(chuàng)建過(guò)程，并使用disableOriginalConstructor()方法來(lái)禁用原始構(gòu)造函數(shù)。接著，我們使用expects()方法來(lái)設(shè)置構(gòu)造函數(shù)的參數(shù)，并在willReturn()方法中返回我們的期望值。

最后，我們使用assertEquals()斷言來(lái)驗(yàn)證add()方法是否返回我們預(yù)期的值。

三、總結(jié)

Mock測(cè)試可以輕松地幫助我們?cè)诓恍枰鎸?shí)依賴(lài)的情況下進(jìn)行測(cè)試。在PHPUnit中，PHPUnitFrameworkMockObjectMockBuilder類(lèi)可以幫助我們創(chuàng)建Mock對(duì)象并進(jìn)行Mock測(cè)試。

在使用MockBuilder創(chuàng)建Mock對(duì)象時(shí)，我們可以設(shè)置需要模擬的屬性和方法，包括方法的返回值和調(diào)用次數(shù)，甚至模擬構(gòu)造函數(shù)。Mock測(cè)試可以使我們的測(cè)試更加簡(jiǎn)單和高效，并且隔離了我們的代碼與外部依賴(lài)的測(cè)試。

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