public function testPrepareDataSource() { $item = ['test_data' => 'some_data', 'field_name' => self::TEST_TIME]; $dateTime = new \DateTime(self::TEST_TIME); $this->timezoneMock->expects($this->once())->method('date')->willReturn($dateTime); $result = $this->model->prepareDataSource(['data' => ['items' => [$item]]]); $this->assertEquals(self::TEST_TIME, $result['data']['items'][0]['field_name']); }