public function testWriteCsv() { $stream = new Magento_Filesystem_Stream_Local($this->_writeFileName); $stream->open(new Magento_Filesystem_Stream_Mode('w')); $stream->writeCsv(array('data1', 'data2')); $stream->open(new Magento_Filesystem_Stream_Mode('r')); $this->assertEquals(array('data1', 'data2'), $stream->readCsv()); }