add additional safety checks to insert/append card methods (#94)

Shuffle-iOS.podspec

@@ -1,7 +1,7 @@
 Pod::Spec.new do |s|
 
 s.name         = "Shuffle-iOS"
-s.version      = "0.3.0"
+s.version      = "0.3.1"
 s.platform     = :ios, "9.0"
 s.summary      = "A multi-directional card swiping library inspired by Tinder"
 
@@ -13,7 +13,7 @@ s.homepage     = "https://github.com/mac-gallagher/Shuffle"
 s.documentation_url = "https://github.com/mac-gallagher/Shuffle/tree/master/README.md"
 s.license      = { :type => 'MIT', :file => 'LICENSE' }
 s.author       = { "Mac Gallagher" => "[email protected]" }
-s.source       = { :git => "https://github.com/mac-gallagher/Shuffle.git", :tag => "v0.3.0" }
+s.source       = { :git => "https://github.com/mac-gallagher/Shuffle.git", :tag => "v0.3.1" }
 
 s.swift_version = "5.0"
 s.source_files = "Sources/**/*.{h,swift}"

Shuffle.xcodeproj/project.pbxproj

@@ -75,6 +75,7 @@
 		ADA444D922AC658E00AFAFFE /* SwipeCardStackDataSource.swift in Sources */ = {isa = PBXBuildFile; fileRef = ADA444D822AC658E00AFAFFE /* SwipeCardStackDataSource.swift */; };
 		ADA444DB22AC662C00AFAFFE /* CardStackAnimator.swift in Sources */ = {isa = PBXBuildFile; fileRef = ADA444DA22AC662C00AFAFFE /* CardStackAnimator.swift */; };
 		ADA444DF22AC682400AFAFFE /* CardStackLayoutProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = ADA444DE22AC682400AFAFFE /* CardStackLayoutProvider.swift */; };
+		ADAC94E224B558EC00F5D52E /* StringUtils.swift in Sources */ = {isa = PBXBuildFile; fileRef = ADAC94E124B558EC00F5D52E /* StringUtils.swift */; };
 		ADC3622D2466B23E00FB9F1C /* SwipeCardSpec_Base.swift in Sources */ = {isa = PBXBuildFile; fileRef = ADC3622C2466B23E00FB9F1C /* SwipeCardSpec_Base.swift */; };
 		ADCEAE2022A1B80B002A5F82 /* CardAnimatorSpec.swift in Sources */ = {isa = PBXBuildFile; fileRef = ADCEAE1F22A1B80B002A5F82 /* CardAnimatorSpec.swift */; };
 		ADCEAE2222A1B88D002A5F82 /* TestableCardAnimator.swift in Sources */ = {isa = PBXBuildFile; fileRef = ADCEAE2122A1B88D002A5F82 /* TestableCardAnimator.swift */; };
@@ -185,6 +186,7 @@
 		ADA444D822AC658E00AFAFFE /* SwipeCardStackDataSource.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SwipeCardStackDataSource.swift; sourceTree = "<group>"; };
 		ADA444DA22AC662C00AFAFFE /* CardStackAnimator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CardStackAnimator.swift; sourceTree = "<group>"; };
 		ADA444DE22AC682400AFAFFE /* CardStackLayoutProvider.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CardStackLayoutProvider.swift; sourceTree = "<group>"; };
+		ADAC94E124B558EC00F5D52E /* StringUtils.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StringUtils.swift; sourceTree = "<group>"; };
 		ADB8EED122F174BB004F8633 /* README.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; path = README.md; sourceTree = "<group>"; };
 		ADC3622C2466B23E00FB9F1C /* SwipeCardSpec_Base.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SwipeCardSpec_Base.swift; sourceTree = "<group>"; };
 		ADCEAE1F22A1B80B002A5F82 /* CardAnimatorSpec.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CardAnimatorSpec.swift; sourceTree = "<group>"; };
@@ -425,6 +427,7 @@
 				ADDF5F832277FA2C00274C09 /* CGPoint+Extensions.swift */,
 				AD72AC752270F4130083E735 /* CGVector+Extensions.swift */,
 				AD2E1C8F245E176F00A520A3 /* PanGestureRecognizer.swift */,
+				ADAC94E124B558EC00F5D52E /* StringUtils.swift */,
 				AD439DF72285FB7E009DE2F7 /* TapGestureRecognizer.swift */,
 				AD4AACA2231C61FC008EC632 /* UIView+Extensions.swift */,
 			);
@@ -821,6 +824,7 @@
 				AD52EF8122E5088B0063AE5D /* CardTransformProvider.swift in Sources */,
 				AD514C5B22A08D5600BD8F3E /* CardLayoutProvider.swift in Sources */,
 				AD72AC9A2270FCCE0083E735 /* SwipeDirection.swift in Sources */,
+				ADAC94E224B558EC00F5D52E /* StringUtils.swift in Sources */,
 				ADA444D922AC658E00AFAFFE /* SwipeCardStackDataSource.swift in Sources */,
 				AD52EF8722E523020063AE5D /* CardStackTransformProvider.swift in Sources */,
 				ADEE86D722ACE5AA00AAE7A1 /* Array+Extensions.swift in Sources */,

Sources/Shuffle/Internal/StringUtils.swift

@@ -0,0 +1,37 @@
+/// 
+/// MIT License
+///
+/// Copyright (c) 2020 Mac Gallagher
+///
+/// Permission is hereby granted, free of charge, to any person obtaining a copy
+/// of this software and associated documentation files (the "Software"), to deal
+/// in the Software without restriction, including without limitation the rights
+/// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+/// copies of the Software, and to permit persons to whom the Software is
+/// furnished to do so, subject to the following conditions:
+///
+/// The above copyright notice and this permission notice shall be included in all
+/// copies or substantial portions of the Software.
+///
+/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+/// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+/// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+/// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+/// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+/// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+/// SOFTWARE.
+///
+
+import Foundation
+
+//swiftlint:disable line_length
+enum StringUtils {
+
+  static func createInvalidUpdateErrorString(newCount: Int,
+                                             oldCount: Int,
+                                             insertedCount: Int = 0,
+                                             deletedCount: Int = 0) -> String {
+    return "Invalid update: invalid number of cards. The number of cards contained in the card stack after the update (\(newCount)) must be equal to the number of cards contained in the card stack before the update (\(oldCount)), plus or minus the number of cards inserted or deleted (\(insertedCount) inserted, \(deletedCount) deleted)"
+  }
+}
+//swiftlint:enable line_length

Sources/Shuffle/SwipeCardStack/CardStackStateManager.swift

@@ -29,6 +29,7 @@ typealias Swipe = (index: Int, direction: SwipeDirection)
 protocol CardStackStateManagable {
   var remainingIndices: [Int] { get }
   var swipes: [Swipe] { get }
+  var totalIndexCount: Int { get }
 
   func insert(_ index: Int, at position: Int)
 
@@ -51,6 +52,10 @@ class CardStackStateManager: CardStackStateManagable {
   /// An array containing the swipe history of the card stack.
   var swipes: [Swipe] = []
 
+  var totalIndexCount: Int {
+    return remainingIndices.count + swipes.count
+  }
+
   func insert(_ index: Int, at position: Int) {
     if position < 0 {
       fatalError("Attempt to insert card at position \(position)")
@@ -65,9 +70,9 @@ class CardStackStateManager: CardStackStateManagable {
       fatalError("Attempt to insert card at data source index \(index)")
     }
 
-    if index > remainingIndices.count + swipes.count {
+    if index > totalIndexCount {
       //swiftlint:disable:next line_length
-      fatalError("Attempt to insert card at index \(index), but there are only \(remainingIndices.count + swipes.count + 1) cards after the update")
+      fatalError("Attempt to insert card at index \(index), but there are only \(totalIndexCount + 1) cards after the update")
     }
 
     // Increment all stored indices in the range [0, index] by 1

Sources/Shuffle/SwipeCardStack/SwipeCardStack.swift

@@ -312,16 +312,42 @@ open class SwipeCardStack: UIView, SwipeCardDelegate, UIGestureRecognizerDelegat
   ///   - position: The position of the new card in the card stack. This position should be determined on
   ///   the returned value of `numberOfRemainingCards`.
   public func insertCard(atIndex index: Int, position: Int) {
+    guard let dataSource = dataSource else { return }
+
+    let oldNumberOfCards = stateManager.totalIndexCount
+    let newNumberOfCards = dataSource.numberOfCards(in: self)
+
     stateManager.insert(index, at: position)
+
+    if newNumberOfCards != oldNumberOfCards + 1 {
+      let errorString = StringUtils.createInvalidUpdateErrorString(newCount: newNumberOfCards,
+                                                                   oldCount: oldNumberOfCards,
+                                                                   insertedCount: 1)
+      fatalError(errorString)
+    }
+
     reloadVisibleCards()
   }
 
   /// Appends a collection of new cards with the specifed indices to the bottom of the card stack.
   /// - Parameter indices: The indices of the cards in the data source.
   public func appendCards(atIndices indices: [Int]) {
+    guard let dataSource = dataSource else { return }
+
+    let oldNumberOfCards = stateManager.totalIndexCount
+    let newNumberOfCards = dataSource.numberOfCards(in: self)
+
     for index in indices {
       stateManager.insert(index, at: numberOfRemainingCards())
     }
+
+    if newNumberOfCards != oldNumberOfCards + indices.count {
+      let errorString = StringUtils.createInvalidUpdateErrorString(newCount: newNumberOfCards,
+                                                                   oldCount: oldNumberOfCards,
+                                                                   insertedCount: indices.count)
+      fatalError(errorString)
+    }
+
     reloadVisibleCards()
   }
 

Tests/ShuffleTests/SwipeCard/Specs/SwipeCardSpec_Base.swift

@@ -36,7 +36,6 @@ class SwipeCardSpec_Base: QuickSpec {
     var mockCardTransformProvider: MockCardTransformProvider!
     var mockSwipeCardDelegate: MockSwipeCardDelegate!
     var mockNotificationCenter: TestableNotificationCenter!
-    var testPanGestureRecognizer: PanGestureRecognizer!
     var subject: TestableSwipeCard!
 
     beforeEach {
@@ -51,8 +50,6 @@ class SwipeCardSpec_Base: QuickSpec {
                                   notificationCenter: mockNotificationCenter,
                                   transformProvider: mockCardTransformProvider)
       subject.delegate = mockSwipeCardDelegate
-
-      testPanGestureRecognizer = subject.panGestureRecognizer as? PanGestureRecognizer
     }
 
     describe("Initialization") {

Tests/ShuffleTests/SwipeCardStack/Mocks/MockCardStackStateManager.swift

@@ -28,8 +28,8 @@ import UIKit
 class MockCardStackStateManager: CardStackStateManagable {
 
   var remainingIndices: [Int] = []
-
   var swipes: [Swipe] = []
+  var totalIndexCount: Int = 0
 
   var insertCalled: Bool = false
   var insertIndices: [Int] = []

Tests/ShuffleTests/SwipeCardStack/Specs/SwipeCardStackSpec_MainMethods.swift

@@ -504,18 +504,53 @@ class SwipeCardStackSpec_MainMethods: QuickSpec {
       let index: Int = 1
       let position: Int = 2
 
-      beforeEach {
-        subject.insertCard(atIndex: index, position: position)
-      }
+      context("and there is no data source") {
+        beforeEach {
+          subject.insertCard(atIndex: index, position: position)
+        }
 
-      it("should call the stateManager's insert method with the correct parameters") {
-        expect(mockStateManager.insertCalled) == true
-        expect(mockStateManager.insertIndices) == [index]
-        expect(mockStateManager.insertPositions) == [position]
+        it("should not call the stateManager's insert method or reloadVisibleCards") {
+          expect(mockStateManager.insertCalled) == false
+          expect(subject.reloadVisibleCardsCalled) == false
+        }
       }
 
-      it("should call reloadVisibleCards") {
-        expect(subject.reloadVisibleCardsCalled) == true
+      context("and there is a data source") {
+        let newNumberOfCards: Int = 10
+        var dataSource: MockSwipeCardStackDataSource!
+
+        beforeEach {
+          dataSource = MockSwipeCardStackDataSource()
+          dataSource.testNumberOfCards = newNumberOfCards
+          subject.dataSource = dataSource
+        }
+
+        context("and the new number of cards is not equal to the old number of cards plus one") {
+          beforeEach {
+            mockStateManager.totalIndexCount = newNumberOfCards - 2
+          }
+
+          it("should throw a fatal error") {
+            expect(subject.insertCard(atIndex: index, position: position)).to(throwAssertion())
+          }
+        }
+
+        context("and the new number of cards is not equal to the old number of cards plus one") {
+          beforeEach {
+            mockStateManager.totalIndexCount = newNumberOfCards - 1
+            subject.insertCard(atIndex: index, position: position)
+          }
+
+          it("should call the stateManager's insert method with the correct parameters") {
+            expect(mockStateManager.insertCalled) == true
+            expect(mockStateManager.insertIndices) == [index]
+            expect(mockStateManager.insertPositions) == [position]
+          }
+
+          it("should call reloadVisibleCards") {
+            expect(subject.reloadVisibleCardsCalled) == true
+          }
+        }
       }
     }
 
@@ -527,18 +562,56 @@ class SwipeCardStackSpec_MainMethods: QuickSpec {
 
       beforeEach {
         mockStateManager.remainingIndices = remainingIndices
-        subject.appendCards(atIndices: indices)
       }
 
-      it("should call the stateManager's insert method with the correct parameters") {
-        expect(mockStateManager.insertCalled) == true
-        expect(mockStateManager.insertIndices) == indices
-        expect(mockStateManager.insertPositions) == Array(repeating: remainingIndices.count,
-                                                          count: indices.count)
+      context("and there is no data source") {
+        beforeEach {
+          subject.appendCards(atIndices: indices)
+        }
+
+        it("should not call the stateManager's insert method or reloadVisibleCards") {
+          expect(mockStateManager.insertCalled) == false
+          expect(subject.reloadVisibleCardsCalled) == false
+        }
       }
 
-      it("should call reloadVisibleCards") {
-        expect(subject.reloadVisibleCardsCalled) == true
+      context("and there is a data source") {
+        let newNumberOfCards: Int = 8
+        var dataSource: MockSwipeCardStackDataSource!
+
+        beforeEach {
+          dataSource = MockSwipeCardStackDataSource()
+          dataSource.testNumberOfCards = newNumberOfCards
+          subject.dataSource = dataSource
+        }
+
+        context("and the new number of cards is not equal to the old number of cards plus the number of new cards") {
+          beforeEach {
+            mockStateManager.totalIndexCount = newNumberOfCards - 2
+          }
+
+          it("should throw a fatal error") {
+            expect(subject.appendCards(atIndices: indices)).to(throwAssertion())
+          }
+        }
+
+        context("and the new number of cards is equal to the old number of cards plus the number of new cards") {
+          beforeEach {
+            mockStateManager.totalIndexCount = newNumberOfCards - indices.count
+            subject.appendCards(atIndices: indices)
+          }
+
+          it("should call the stateManager's insert method with the correct parameters") {
+            expect(mockStateManager.insertCalled) == true
+            expect(mockStateManager.insertIndices) == indices
+            expect(mockStateManager.insertPositions) == Array(repeating: remainingIndices.count,
+                                                              count: indices.count)
+          }
+
+          it("should call reloadVisibleCards") {
+            expect(subject.reloadVisibleCardsCalled) == true
+          }
+        }
       }
     }