Fix FingerUp causing UITouch to end in start location

Author: nsoojin

Sources/Hammer/EventGenerator/EventGenerator+Hand/EventGenerator+Hand.swift

@@ -498,6 +498,7 @@ extension EventGenerator {
                 throw HammerError.touchForFingerDoesNotExist(index: finger.fingerIndex)
             }
 
+            try self.activeTouches.update(finger: finger, forIdentifier: existingIdentifier)
             return existingIdentifier
         case .ended, .cancelled:
             guard let existingIdentifier = existingIdentifier else {

Sources/Hammer/Utilties/TouchStorage.swift

@@ -54,4 +54,9 @@ struct TouchStorage {
             self.stylusStore = nil
         }
     }
+  
+    mutating func update(finger: FingerInfo, forIdentifier identifier: UInt32) throws {
+        self.fingerStore.removeAll { $0.identifier == identifier }
+        self.fingerStore.append((finger, identifier))
+    }
 }

Tests/HammerTests/DragTests.swift

@@ -0,0 +1,24 @@
+import Hammer
+import XCTest
+import Foundation
+
+final class DragTests: XCTestCase {
+  
+    func test_drag() throws {
+        let view = TouchTestView()
+        
+        view.widthAnchor.constraint(equalToConstant: 300).isActive = true
+        view.heightAnchor.constraint(equalToConstant: 300).isActive = true
+        
+        let eventGenerator = try EventGenerator(view: view)
+        try eventGenerator.waitUntilHittable(timeout: 1)
+        
+        try eventGenerator.fingerDown(at: view.frame.center.offset(x: -50, y: 0))
+        try eventGenerator.fingerMove(to: view.frame.center.offset(x: 50, y: 0), duration: 0.3)
+        try eventGenerator.fingerUp()
+
+        let endPoint = view.touches.first!.location(in: view)
+        XCTAssertEqual(endPoint, CGPoint(x: 200, y: 150), accuracy: 0.001)
+    }
+  
+}

Tests/HammerTests/Utilities/TouchTestView.swift

@@ -0,0 +1,13 @@
+import UIKit
+
+final class TouchTestView: UIView {
+  
+  var touches: Set<UITouch> = .init()
+  
+  override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
+    super.touchesBegan(touches, with: event)
+    
+    touches.forEach { self.touches.insert($0) }
+  }
+  
+}