有没有办法使用XCTest对Touch Id进行单元测试？

Question

Is there a way to unit test TouchId's "evaluatePolicy" or "canevaluatePolicy" using XCTest? I want to unit test using simulator as base.

Thanks

Answer 1

I have described one way of writing unit test for Touch ID code in this post .

Basically, if you have some Touch ID managing class similar to this one:

final public class TouchIDManager {

    /// Authentication context object we use for Touch ID. Typically it's just a `LAContext` instance that is mocked when testing.
    internal var authenticationContext = LAContext()

    /**
     Checks Touch ID availability.

     - returns: Flag indicating if Touch ID is available
     */
    public func touchIDAvailable() -> Bool {
        return authenticationContext.canEvaluatePolicy(LAPolicy.DeviceOwnerAuthenticationWithBiometrics, error: nil)
    }

    /**
     Authenticates the user with Touch ID

     - parameter completion: Completion handler
         */
    public func authenticate(completion: (success: Bool) -> ()) {
        guard touchIDAvailable() else {
            completion(false)
            return
        }
        authenticationContext.evaluatePolicy(LAPolicy.DeviceOwnerAuthenticationWithBiometrics, localizedReason: "Wanna Touch my ID?") {
            (success: Bool, error: NSError?) -> Void in
            completion(success: success)
        }
    }
}

You can simply fake the LAContext behaviour with a StubLAContext class:

func testSuccessfulAuthentication() {
    /// A class faking Touch ID availability and successful user verification
    class StubLAContext: LAContext {
        override func evaluatePolicy(policy: LAPolicy, localizedReason: String, reply: (Bool, NSError?) -> Void) { reply(true, nil) }
        override func canEvaluatePolicy(policy: LAPolicy, error: NSErrorPointer) -> Bool { return true }
    }

    let manager = TouchIDManager()
    manager.authenticationContext = StubLAContext()

    manager.authenticate { (success) in
        XCTAssertTrue(success)
    }
}

Clearly this particular test doesn't do much, but it might be a good starting point to test other Touch ID related logic you have in your application.