如果我正在编写接口,我通常会指定实现应该公开的行为。为了确保这种行为,应该针对这个接口编写测试。我如何最好地编写和组织这些测试,以便实现的编写者能够轻松地使用它们,以确保它们的实现满足要求?扩展(编写子类)接口测试的某种方式是可行的吗?还是我实现了一些像工厂这样的设计模式?
我明白为什么人们告诉你不应该测试接口。但这不是你要问的。您正在寻求一种更简单的方法来为实现某个接口的多个类执行相同的单元测试。我使用@dataProvider注释(PHPUnit,是的)来实现这一点。
假设您有以下类:
interface Shape {
public function getNumberOfSides();
}
class Triangle implements Shape {
private $sides = 3;
public function getNumberOfSides() {
return $this->sides;
}
}
class Square implements Shape {
private $sides = 4;
public function getNumberOfSides() {
return $this->sides;
}
}
现在要测试的是,对于Triangle
的实例,定义了getNumberOfSides
并返回3,而对于Square
,则返回4。以下是使用@dataProvider
:编写此测试的方式
class ShapeTest extends PHPUnit_Framework_TestCase {
/**
* @dataProvider numberOfSidesDataProvider
*/
public function testNumberOfSides(Shape $shape, $expectedSides){
$this->assertEquals($shape->getNumberOfSides(), $expectedSides);
}
public function numberOfSidesDataProvider() {
return array(
array(new Square(), 5),
array(new Triangle(), 3)
);
}
}
在这里运行phpunit会产生预期的输出:
There was 1 failure:
1) ShapeTest::testNumberOfSides with data set #0 (Square Object (...), 5)
Failed asserting that 5 matches expected 4.
/tests/ShapeTest.php:12
FAILURES!
Tests: 2, Assertions: 2, Failures: 1.
您可以创建一个抽象类,其中包含一些接口契约的基本测试。
考虑以下示例:
interface FactorialComputer {
public function compute($input);
}
class RecursiveFactorialComputer implements FactorialComputer {
public function compute($input) {
if ($input < 0) {
throw new InvalidArgumentException(...);
}
if ($input == 0 || $input == 1) {
return 1;
}
return $input * $this->compute($input - 1);
}
}
class IterativeFactorialComputer implements FactorialComputer {
public function compute($input) {
$result = 1;
for ($i = 1; $i <= $input; $i++) {
$result *= $i;
}
return $result;
}
}
以及两种实现的测试:
abstract class AbstractFactorialComputerTest extends PHPUnit_Framework_TestCase {
/**
* @var FactorialComputer
*/
protected $instance;
protected abstract function getComputerInstance();
public function setUp() {
$this->instance = $this->getComputerInstance;
}
/**
* @expectedException InvalidArgumentException
*/
public function testExceptionOnInvalidArgument() {
$this->instance->compute(-1);
}
public function testEdgeCases()
{
$this->assertEquals(1, $this->instance->compute(0));
$this->assertEquals(1, $this->instance->compute(1));
}
...
}
class RecursiveFactorialComputerTest extends AbstractFactorialComputerTest
{
protected abstract function getComputerInstance() {
return new RecursiveFactorialComputer();
}
public function testComputeMethodCallsCount() {
// get mock and test number of compute() calls
}
}
class IterativeFactorialComputerTest extends AbstractFactorialComputerTest
{
protected abstract function getComputerInstance() {
return new IterativeFactorialComputer();
}
}
使用这种方法,每个程序员都应该能够为接口实现创建一个完整的单元测试。