[ASDisplayNode] Add unit tests for layout z-order changes (with an open issue to fix).

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## master
 * Add your own contributions to the next release on the line below this with your name.
+- [ASDisplayNode] Add unit tests for layout z-order changes (with an open issue to fix).
 - [ASDisplayNode] Consolidate main thread initialization and allow apps to invoke it manually instead of +load.
 - [ASRunloopQueue] Introduce new runloop queue(ASCATransactionQueue) to coalesce Interface state update calls for view controller transitions.
 - [ASRangeController] Fix stability of "minimum" rangeMode if the app has more than one layout before scrolling.

Tests/ASDisplayNodeTests.mm

@@ -33,6 +33,7 @@
 #import <AsyncDisplayKit/ASImageNode.h>
 #import <AsyncDisplayKit/ASOverlayLayoutSpec.h>
 #import <AsyncDisplayKit/ASInsetLayoutSpec.h>
+#import <AsyncDisplayKit/ASStackLayoutSpec.h>
 #import <AsyncDisplayKit/ASCenterLayoutSpec.h>
 #import <AsyncDisplayKit/ASBackgroundLayoutSpec.h>
 #import <AsyncDisplayKit/ASInternalHelpers.h>
@@ -2374,6 +2375,46 @@ - (void)testThatHavingTheSameNodeTwiceInALayoutSpecCausesExceptionOnLayoutCalcul
   XCTAssertThrowsSpecificNamed([node calculateLayoutThatFits:ASSizeRangeMake(CGSizeMake(100, 100))], NSException, NSInternalInconsistencyException);
 }
 
+- (void)testThatStackSpecOrdersSubnodesCorrectly
+{
+  // This test ensures that the z-order of nodes matches the stack spec, including after relayout / transition.
+  ASDisplayNode *node = [[ASDisplayNode alloc] init];
+  node.automaticallyManagesSubnodes = YES;
+
+  DeclareNodeNamed(a);
+  DeclareNodeNamed(b);
+  DeclareNodeNamed(c);
+  DeclareNodeNamed(d);
+
+  NSArray *nodesForwardOrder = @[a, b, c, d];
+  NSArray *nodesReverseOrder = @[d, c, b, a];
+  __block BOOL flipItemOrder = NO;
+
+  node.layoutSpecBlock = ^(ASDisplayNode *node, ASSizeRange size) {
+    ASStackLayoutSpec *stack = [ASStackLayoutSpec verticalStackLayoutSpec];
+    stack.children = flipItemOrder ? nodesReverseOrder : nodesForwardOrder;
+    return stack;
+  };
+
+  ASDisplayNodeSizeToFitSize(node, CGSizeMake(100, 100));
+  [node.view layoutIfNeeded];
+
+  // Because automaticallyManagesSubnodes is used, the subnodes array is constructed from the layout spec's children.
+  XCTAssert([node.subnodes isEqualToArray:nodesForwardOrder], @"subnodes: %@, array: %@", node.subnodes, nodesForwardOrder);
+  XCTAssertNodeSubnodeSubviewSublayerOrder(node, YES /* isLoaded */, NO /* isLayerBacked */,
+                                           @"a,b,c,d", @"Forward order");
+
+  flipItemOrder = YES;
+  [node invalidateCalculatedLayout];
+  [node.view layoutIfNeeded];
+
+  // In this case, it's critical that the items are in the new order so that event handling and apparent z-position are correct.
+  // FIXME: The reversal case is not currently passing.
+  // XCTAssert([node.subnodes isEqualToArray:nodesReverseOrder], @"subnodes: %@, array: %@", node.subnodes, nodesReverseOrder);
+  // XCTAssertNodeSubnodeSubviewSublayerOrder(node, YES /* isLoaded */, NO /* isLayerBacked */,
+  //                                          @"d,c,b,a", @"Reverse order");
+}
+
 - (void)testThatOverlaySpecOrdersSubnodesCorrectly
 {
   ASDisplayNode *node = [[ASDisplayNode alloc] init];

Tests/ArrayDiffingTests.m

@@ -65,10 +65,14 @@ - (void)testDiffingCommonIndexes
     NSIndexSet *indexSet = [test[0] _asdk_commonIndexesWithArray:test[1] compareBlock:^BOOL(id lhs, id rhs) {
       return [lhs isEqual:rhs];
     }];
+    NSMutableIndexSet *mutableIndexSet = [indexSet mutableCopy];
 
     for (NSNumber *index in (NSArray *)test[2]) {
       XCTAssert([indexSet containsIndex:[index integerValue]]);
+      [mutableIndexSet removeIndex:[index integerValue]];
     }
+
+    XCTAssert([mutableIndexSet count] == 0, @"Unaccounted deletions: %@", mutableIndexSet);
   }
 }
 
@@ -80,6 +84,12 @@ - (void)testDiffingInsertionsAndDeletions {
         @[@3],
         @[],
       ],
+      @[
+        @[@"a", @"b", @"c", @"d"],
+        @[@"d", @"c", @"b", @"a"],
+        @[@1, @2, @3],
+        @[@0, @1, @2],
+      ],
       @[
         @[@"bob", @"alice", @"dave"],
         @[@"bob", @"gary", @"alice", @"dave"],
@@ -121,12 +131,20 @@ - (void)testDiffingInsertionsAndDeletions {
   for (NSArray *test in tests) {
     NSIndexSet *insertions, *deletions;
     [test[0] asdk_diffWithArray:test[1] insertions:&insertions deletions:&deletions];
+    NSMutableIndexSet *mutableInsertions = [insertions mutableCopy];
+    NSMutableIndexSet *mutableDeletions = [deletions mutableCopy];
+
     for (NSNumber *index in (NSArray *)test[2]) {
-      XCTAssert([insertions containsIndex:[index integerValue]]);
+      XCTAssert([mutableInsertions containsIndex:[index integerValue]]);
+      [mutableInsertions removeIndex:[index integerValue]];
     }
     for (NSNumber *index in (NSArray *)test[3]) {
-      XCTAssert([deletions containsIndex:[index integerValue]]);
+      XCTAssert([mutableDeletions containsIndex:[index integerValue]]);
+      [mutableDeletions removeIndex:[index integerValue]];
     }
+
+    XCTAssert([mutableInsertions count] == 0, @"Unaccounted insertions: %@", mutableInsertions);
+    XCTAssert([mutableDeletions count] == 0, @"Unaccounted deletions: %@", mutableDeletions);
   }
 }