[英]Is there a way to write a test of a `SKPhysicsContactDelegate` functions?
Can I mock SKPhysicsContact
object to feed into -(void)didEndContact:(SKPhysicsContact *)contact
method? 我可以模拟SKPhysicsContact
对象以馈入-(void)didEndContact:(SKPhysicsContact *)contact
方法吗? Or is there any other technique, that can be leveraged here? 还是在这里可以利用其他任何技术?
class PhysicsTestCase: XCTestCase {
var physics: GamePhysics!
...
func testCaseOfCollisionsHandling() {
let contact = SKPhysicsContact()
contact.bodyA = SKPhysicsBody(circleOfRadius: 10) // Error, 'bodyA' is get-only property
physics.didEnd(contact) // Physics conforms to `SKPhysicsContactDelegate`
}
...
}
...
// The class that is being tested
class GamePhysics: NSObject, SKPhysicsContactDelegate {
// MARK: - SKPhysicsContactDelegate
func didBegin(_ contact: SKPhysicsContact) {
guard let nodeA = contact.bodyA.node, let nodeB = contact.bodyB.node else {
fatalError("No nodes in colliding bodies")
}
switch (nodeB, nodeA) {
case let (ball as LogicalBall, tile as LogicalTile):
// Performing some logic
...
}
}
func didEnd(_ contact: SKPhysicsContact) {
...
}
...
}
When we can't change a type because we don't own the API, the solution is to use the legacy code technique Subclass and Override Method: 当我们由于不拥有API而无法更改类型时,解决方案是使用遗留代码技术Subclass和Override Method:
class TestablePhysicsContact: SKPhysicsContact {
var stubbedBodyA: SKPhysicsBody?
override var bodyA: SKPhysicsBody {
return stubbedBodyA!
}
}
To use this in your example test: 要在示例测试中使用它,请执行以下操作:
func testCaseOfCollisionsHandling() {
let contact = TestablePhysicsContact()
contact.stubbedBodyA = SKPhysicsBody(circleOfRadius: 10)
physics.didEnd(contact)
// assert something
}
For more on this technique, see https://qualitycoding.org/swift-partial-mock/ 有关此技术的更多信息,请参见https://qualitycoding.org/swift-partial-mock/
Although, subclassing proposed by Jon Reid in https://stackoverflow.com/a/44101485/482853 is very neat, I didn't managed to make it work in this particular case because of elusive nature of SKPhysicsContact
class itself. 虽然,乔恩·里德(Jon Reid)在https://stackoverflow.com/a/44101485/482853中提出的子类非常整洁,但由于SKPhysicsContact
类本身的难以捉摸的特性,我未能使其在这种特殊情况下SKPhysicsContact
。
The way this problem can be solved is to use good old Objective C runtime: 解决此问题的方法是使用良好的旧Objective C运行时:
func testBallsCollisionIsPassedToHandler() {
let ballAMock = LogicalBallMock()
let bodyA = SKPhysicsBody(circleOfRadius: 10)
bodyA.perform(Selector(("setRepresentedObject:")), with: ballAMock) // So the bodyA.node will return ballAMock
let ballBMock = LogicalBallMock()
let bodyB = SKPhysicsBody(circleOfRadius: 10)
bodyB.perform(Selector(("setRepresentedObject:")), with: ballBMock) // So the bodyB.node will return ballBMock
let contact = SKPhysicsContact()
contact.perform(Selector(("setBodyA:")), with: bodyA)
contact.perform(Selector(("setBodyB:")), with: bodyB)
physics.didEnd(contact)
// Assertions ...
}
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