Since #12006, the `ContainerBuilder` contains the
`addExpressionLanguageProvider()` method which references a class from
the ExpressionLanguage component. By default, the PHPUnit mock API
tries to mock all methods of the class being doubled. Since the
ExpressionLanguage component is not required to run the tests,
creating the mock objects fails when the mock API fails to mock
the `addExpressionLanguageProvider()` method.