phpunitHow to mock a private method in PHPUnit?

Mocking private methods in PHPUnit is possible using the getMockBuilder method.

$mock = $this->getMockBuilder(MyClass::class)
    ->setMethods(['myPrivateMethod'])
    ->getMock();

$mock->expects($this->once())
    ->method('myPrivateMethod')
    ->willReturn('mocked result');

The above code will create a mock object of MyClass and override the myPrivateMethod method with a mocked result.

• getMockBuilder: creates a mock object of the specified class
• setMethods: overrides the specified methods with mocked results
• expects: specifies the expectation of the mocked method
• method: specifies the method to be mocked
• willReturn: specifies the return value of the mocked method

Helpful links

• https://phpunit.readthedocs.io/en/9.2/test-doubles.html#test-doubles
• https://phpunit.readthedocs.io/en/9.2/test-doubles.html#mocking-private-methods

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