jsonEncoderMock = $this->getMockBuilder(\Magento\Framework\Json\EncoderInterface::class) ->disableOriginalConstructor() ->getMock(); $this->jsonDecoderMock = $this->getMockBuilder(\Magento\Framework\Json\DecoderInterface::class) ->disableOriginalConstructor() ->getMock(); $this->helper = $objectManager->getObject( \Magento\Framework\Json\Helper\Data::class, [ 'jsonEncoder' => $this->jsonEncoderMock, 'jsonDecoder' => $this->jsonDecoderMock, ] ); } public function testJsonEncode() { $expected = '"valueToEncode"'; $valueToEncode = 'valueToEncode'; $this->jsonEncoderMock->expects($this->once()) ->method('encode') ->willReturn($expected); $this->assertEquals($expected, $this->helper->jsonEncode($valueToEncode)); } public function testJsonDecode() { $expected = '"valueToDecode"'; $valueToDecode = 'valueToDecode'; $this->jsonDecoderMock->expects($this->once()) ->method('decode') ->willReturn($expected); $this->assertEquals($expected, $this->helper->jsonDecode($valueToDecode)); } }