[ 'class' => HTMLSubmittedValueField::class, 'name' => 'bar', ], ] ); $request = new FauxRequest( [ 'foo' => '123', 'bar' => '456', ], true ); $mockClosure = $this->getMockBuilder( 'object' )->setMethods( [ '__invoke' ] )->getMock(); $mockClosure->expects( $this->once() )->method( '__invoke' ) ->with( [ 'foo' => '456' ] )->willReturn( true ); $context = new DerivativeContext( RequestContext::getMain() ); $context->setRequest( $request ); $form->setTitle( Title::newFromText( 'Title' ) ); $form->setContext( $context ); $form->setSubmitCallback( $mockClosure ); $form->prepareForm(); $form->trySubmit(); } }