Add tests to LCS array category

AsyncDisplayKitTests/ArrayDiffingTests.m

@@ -0,0 +1,72 @@
+//
+//  ArrayDiffingTests.m
+//  AsyncDisplayKit
+//
+//  Created by Levi McCallum on 1/29/16.
+//  Copyright © 2016 Facebook. All rights reserved.
+//
+
+#import <XCTest/XCTest.h>
+
+#import "NSArray+Diffing.h"
+
+@interface ArrayDiffingTests : XCTestCase
+
+@end
+
+@implementation ArrayDiffingTests
+
+- (void)testDiffing {
+  NSArray<NSArray *> *tests = @[
+      @[
+        @[@"bob", @"alice", @"dave"],
+        @[@"bob", @"alice", @"dave", @"gary"],
+        @[@3],
+        @[],
+      ],
+      @[
+        @[@"bob", @"alice", @"dave"],
+        @[@"bob", @"gary", @"alice", @"dave"],
+        @[@1],
+        @[],
+      ],
+      @[
+        @[@"bob", @"alice", @"dave"],
+        @[@"bob", @"alice"],
+        @[],
+        @[@2],
+      ],
+      @[
+        @[@"bob", @"alice", @"dave"],
+        @[],
+        @[],
+        @[@0, @1, @2],
+      ],
+      @[
+        @[@"bob", @"alice", @"dave"],
+        @[@"gary", @"alice", @"dave", @"jack"],
+        @[@0, @3],
+        @[@0],
+      ],
+      @[
+        @[@"bob", @"alice", @"dave", @"judy", @"lynda", @"tony"],
+        @[@"gary", @"bob", @"suzy", @"tony"],
+        @[@0, @2],
+        @[@1, @2, @3, @4],
+      ],
+  ];
+  
+  for (NSArray *test in tests) {
+    NSMutableIndexSet *insertions = [NSMutableIndexSet indexSet];
+    NSMutableIndexSet *deletions = [NSMutableIndexSet indexSet];
+    [test[0] asdk_diffWithArray:test[1] insertions:&insertions deletions:&deletions];
+    for (NSNumber *index in (NSArray *)test[2]) {
+      XCTAssert([insertions containsIndex:[index integerValue]]);
+    }
+    for (NSNumber *index in (NSArray *)test[3]) {
+      XCTAssert([deletions containsIndex:[index integerValue]]);
+    }
+  }
+}
+
+@end