Lay some foundation for our new pending state controller

AsyncDisplayKit.xcodeproj/project.pbxproj

@@ -455,6 +455,16 @@
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@@ -786,6 +796,12 @@
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+		CC3B20811C3F76D600798563 /* ASPendingStateController.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASPendingStateController.h; sourceTree = "<group>"; };
+		CC3B20821C3F76D600798563 /* ASPendingStateController.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASPendingStateController.mm; sourceTree = "<group>"; };
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+		CC3B208F1C3F892D00798563 /* ASPendingStateControllerTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASPendingStateControllerTests.m; sourceTree = "<group>"; };
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@@ -1002,6 +1018,8 @@
 			children = (
 				DBC453211C5FD97200B16017 /* ASDisplayNodeImplicitHierarchyTests.m */,
 				DBC452DD1C5C6A6A00B16017 /* ArrayDiffingTests.m */,
+				CC3B208F1C3F892D00798563 /* ASPendingStateControllerTests.m */,
+				CC3B208D1C3F7D0A00798563 /* ASWeakSetTests.m */,
 				057D02C01AC0A66700C7AC3C /* AsyncDisplayKitTestHost */,
 				056D21501ABCEDA1001107EF /* ASSnapshotTestCase.h */,
 				05EA6FE61AC0966E00E35788 /* ASSnapshotTestCase.mm */,
@@ -1123,6 +1141,10 @@
 			children = (
 				DB55C25F1C6408D6004EDCF5 /* _ASTransitionContext.h */,
 				DB55C2601C6408D6004EDCF5 /* _ASTransitionContext.m */,
+				CC3B20811C3F76D600798563 /* ASPendingStateController.h */,
+				CC3B20821C3F76D600798563 /* ASPendingStateController.mm */,
+				CC3B20871C3F7A5400798563 /* ASWeakSet.h */,
+				CC3B20881C3F7A5400798563 /* ASWeakSet.m */,
 				AC026B6D1BD57DBF00BBC17E /* _ASHierarchyChangeSet.h */,
 				AC026B6E1BD57DBF00BBC17E /* _ASHierarchyChangeSet.m */,
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@@ -1413,6 +1435,7 @@
 				257754B51BEE44CD00737CA5 /* ASTextKitTruncating.h in Headers */,
 				ACF6ED4F1B17847A00DA7C62 /* ASStackPositionedLayout.h in Headers */,
 				257754A71BEE44CD00737CA5 /* ASTextKitAttributes.h in Headers */,
+				CC3B20891C3F7A5400798563 /* ASWeakSet.h in Headers */,
 				ACF6ED511B17847A00DA7C62 /* ASStackUnpositionedLayout.h in Headers */,
 				9C6BB3B21B8CC9C200F13F52 /* ASStaticLayoutable.h in Headers */,
 				ACF6ED311B17843500DA7C62 /* ASStaticLayoutSpec.h in Headers */,
@@ -1421,6 +1444,7 @@
 				257754C11BEE458E00737CA5 /* ASTextKitHelpers.h in Headers */,
 				B30BF6521C5964B0004FCD53 /* ASLayoutManager.h in Headers */,
 				0574D5E219C110940097DC25 /* ASTableViewProtocols.h in Headers */,
+				CC3B20831C3F76D600798563 /* ASPendingStateController.h in Headers */,
 				058D0A51195D05CB00B7D73C /* ASTextNode.h in Headers */,
 				058D0A81195D05F900B7D73C /* ASThread.h in Headers */,
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@@ -1475,6 +1499,7 @@
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 				254C6B791BF94DF4003EC431 /* ASTextKitEntityAttribute.h in Headers */,
 				509E68631B3AEDB4009B9150 /* ASCollectionViewLayoutController.h in Headers */,
+				CC3B20841C3F76D600798563 /* ASPendingStateController.h in Headers */,
 				B35061F71B010EFD0018CF92 /* ASCollectionViewProtocols.h in Headers */,
 				DE6EA3231C14000600183B10 /* ASDisplayNode+FrameworkPrivate.h in Headers */,
 				B35061FA1B010EFD0018CF92 /* ASControlNode+Subclasses.h in Headers */,
@@ -1517,6 +1542,7 @@
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 				B350625C1B010F070018CF92 /* ASLog.h in Headers */,
 				0442850E1BAA64EC00D16268 /* ASMultidimensionalArrayUtils.h in Headers */,
+				CC3B208A1C3F7A5400798563 /* ASWeakSet.h in Headers */,
 				DE8BEAC21C2DF3FC00D57C12 /* ASDelegateProxy.h in Headers */,
 				B35062041B010EFD0018CF92 /* ASMultiplexImageNode.h in Headers */,
 				DECBD6E81BE56E1900CF4905 /* ASButtonNode.h in Headers */,
@@ -1611,6 +1637,7 @@
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 				058D09BA195D04C000B7D73C /* Resources */,
 				3B9D88CDF51B429C8409E4B6 /* Copy Pods Resources */,
+				78B4649EC16385BFAFD84D49 /* Embed Pods Frameworks */,
 			);
 			buildRules = (
 			);
@@ -1740,6 +1767,21 @@
 			shellScript = "\"${SRCROOT}/Pods/Target Support Files/Pods-AsyncDisplayKitTests/Pods-AsyncDisplayKitTests-resources.sh\"\n";
 			showEnvVarsInLog = 0;
 		};
+		78B4649EC16385BFAFD84D49 /* Embed Pods Frameworks */ = {
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+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputPaths = (
+			);
+			name = "Embed Pods Frameworks";
+			outputPaths = (
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "\"${SRCROOT}/Pods/Target Support Files/Pods-AsyncDisplayKitTests/Pods-AsyncDisplayKitTests-frameworks.sh\"\n";
+			showEnvVarsInLog = 0;
+		};
 /* End PBXShellScriptBuildPhase section */
 
 /* Begin PBXSourcesBuildPhase section */
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 				058D0A2B195D050800B7D73C /* ASImageNode+CGExtras.m in Sources */,
+				CC3B208B1C3F7A5400798563 /* ASWeakSet.m in Sources */,
 				058D0A16195D050800B7D73C /* ASImageNode.mm in Sources */,
 				430E7C911B4C23F100697A4C /* ASIndexPath.m in Sources */,
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@@ -1815,6 +1858,7 @@
 				058D0A1B195D050800B7D73C /* ASMutableAttributedStringBuilder.m in Sources */,
 				055B9FA91A1C154B00035D6D /* ASNetworkImageNode.mm in Sources */,
 				AEB7B01B1C5962EA00662EF4 /* ASDefaultPlayButton.m in Sources */,
+				CC3B20851C3F76D600798563 /* ASPendingStateController.mm in Sources */,
 				ACF6ED2C1B17843500DA7C62 /* ASOverlayLayoutSpec.mm in Sources */,
 				0442850F1BAA64EC00D16268 /* ASMultidimensionalArrayUtils.mm in Sources */,
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 				9F06E5CD1B4CAF4200F015D8 /* ASCollectionViewTests.m in Sources */,
 				2911485C1A77147A005D0878 /* ASControlNodeTests.m in Sources */,
+				CC3B208E1C3F7D0A00798563 /* ASWeakSetTests.m in Sources */,
 				ACF6ED5D1B178DC700DA7C62 /* ASDimensionTests.mm in Sources */,
 				058D0A38195D057000B7D73C /* ASDisplayLayerTests.m in Sources */,
 				2538B6F31BC5D2A2003CA0B4 /* ASCollectionViewFlowLayoutInspectorTests.m in Sources */,
@@ -1883,6 +1928,7 @@
 				AEEC47E41C21D3D200EC1693 /* ASVideoNodeTests.m in Sources */,
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 				058D0A3D195D057000B7D73C /* ASTextKitCoreTextAdditionsTests.m in Sources */,
+				CC3B20901C3F892D00798563 /* ASPendingStateControllerTests.m in Sources */,
 				058D0A40195D057000B7D73C /* ASTextNodeTests.m in Sources */,
 				DBC453221C5FD97200B16017 /* ASDisplayNodeImplicitHierarchyTests.m in Sources */,
 				058D0A41195D057000B7D73C /* ASTextNodeWordKernerTests.mm in Sources */,
@@ -1936,6 +1982,7 @@
 				B35061FF1B010EFD0018CF92 /* ASDisplayNodeExtras.mm in Sources */,
 				B35062011B010EFD0018CF92 /* ASEditableTextNode.mm in Sources */,
 				254C6B881BF94F8A003EC431 /* ASTextKitRenderer.mm in Sources */,
+				CC3B208C1C3F7A5400798563 /* ASWeakSet.m in Sources */,
 				B350621C1B010EFD0018CF92 /* ASFlowLayoutController.mm in Sources */,
 				B350621E1B010EFD0018CF92 /* ASHighlightOverlayLayer.mm in Sources */,
 				B35062541B010EFD0018CF92 /* ASImageNode+CGExtras.m in Sources */,
@@ -1950,6 +1997,7 @@
 				DECBD6EA1BE56E1900CF4905 /* ASButtonNode.mm in Sources */,
 				254C6B841BF94F8A003EC431 /* ASTextNodeWordKerner.m in Sources */,
 				34EFC76B1B701CEB00AD841F /* ASLayoutSpec.mm in Sources */,
+				CC3B20861C3F76D600798563 /* ASPendingStateController.mm in Sources */,
 				254C6B8C1BF94F8A003EC431 /* ASTextKitTailTruncater.mm in Sources */,
 				B35062051B010EFD0018CF92 /* ASMultiplexImageNode.mm in Sources */,
 				B35062251B010EFD0018CF92 /* ASMutableAttributedStringBuilder.m in Sources */,

AsyncDisplayKit/ASDisplayNode.mm

@@ -981,6 +981,17 @@ static inline void filterNodesInLayoutAtIndexesWithIntersectingNodes(
   _contentsScaleForDisplay = contentsScaleForDisplay;
 }
 
+- (void)applyPendingViewState
+{
+  ASDisplayNodeAssertMainThread();
+  if (self.layerBacked) {
+    [_pendingViewState applyToLayer:self.layer];
+  } else {
+    [_pendingViewState applyToView:self.view];
+  }
+  [_pendingViewState clearChanges];
+}
+
 - (void)displayImmediately
 {
   ASDisplayNodeAssertMainThread();
@@ -2366,13 +2377,7 @@ void recursivelyTriggerDisplayForLayer(CALayer *layer, BOOL shouldBlock)
   // for the view/layer are still valid.
   ASDN::MutexLocker l(_propertyLock);
 
-  if (_flags.layerBacked) {
+  [self applyPendingViewState];
-    [_pendingViewState applyToLayer:_layer];
-  } else {
-    [_pendingViewState applyToView:_view];
-  }
-
-  _pendingViewState = nil;
 
   // TODO: move this into real pending state
   if (_flags.displaySuspended) {

AsyncDisplayKit/Private/ASDisplayNodeInternal.h

@@ -178,6 +178,8 @@ FOUNDATION_EXPORT NSString * const ASRenderingEngineDidDisplayNodesScheduledBefo
 
 @property (nonatomic, assign) CGFloat contentsScaleForDisplay;
 
+- (void)applyPendingViewState;
+
 /**
  * // TODO: NOT YET IMPLEMENTED
  *

AsyncDisplayKit/Private/ASPendingStateController.h

@@ -0,0 +1,45 @@
+//
+//  ASPendingStateController.h
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 1/7/16.
+//  Copyright © 2016 Facebook. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+@class ASDisplayNode;
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ A singleton that is responsible for applying changes to
+ UIView/CALayer properties of display nodes when they
+ have been set on background threads.
+ 
+ This controller will enqueue run-loop events to flush changes
+ but if you need 
+ */
+@interface ASPendingStateController : NSObject
+
++ (ASPendingStateController *)sharedInstance;
+
+@property (nonatomic, readonly) BOOL hasChanges;
+
+/**
+ Flush all pending states for nodes now. Any UIView/CALayer properties
+ that have been set in the background will be applied to their
+ corresponding views/layers before this method returns.
+ 
+ You must call this method on the main thread.
+ */
+- (void)flush;
+
+/**
+ Register this node as having pending state that needs
+ */
+- (void)registerNode:(ASDisplayNode *)node;
+
+@end
+
+NS_ASSUME_NONNULL_END

AsyncDisplayKit/Private/ASPendingStateController.mm

@@ -0,0 +1,99 @@
+//
+//  ASPendingStateController.m
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 1/7/16.
+//  Copyright © 2016 Facebook. All rights reserved.
+//
+
+#import "ASPendingStateController.h"
+#import "ASThread.h"
+#import "ASWeakSet.h"
+#import "ASDisplayNode.h"
+
+@interface ASPendingStateController()
+{
+  ASDN::Mutex _lock;
+
+  struct ASPendingStateControllerFlags {
+    unsigned pendingFlush:1;
+  } _flags;
+}
+
+@property (nonatomic, strong, readonly) ASWeakSet<ASDisplayNode *> *dirtyNodes;
+@end
+
+@implementation ASPendingStateController
+
+#pragma mark Lifecycle & Singleton
+
+- (instancetype)init
+{
+  self = [super init];
+  if (self) {
+    _dirtyNodes = [ASWeakSet new];
+  }
+  return self;
+}
+
++ (ASPendingStateController *)sharedInstance
+{
+  static dispatch_once_t onceToken;
+  static ASPendingStateController *controller;
+  dispatch_once(&onceToken, ^{
+    controller = [ASPendingStateController new];
+  });
+  return controller;
+}
+
+#pragma mark External API
+
+- (void)flush
+{
+  ASDisplayNodeAssertMainThread();
+  [self flushNow];
+}
+
+- (void)registerNode:(ASDisplayNode *)node
+{
+  ASDN::MutexLocker l(_lock);
+  [_dirtyNodes addObject:node];
+
+  [self scheduleFlushIfNeeded];
+}
+
+#pragma mark Private Methods
+
+/**
+ This method is assumed to be called with the lock held.
+ */
+- (void)scheduleFlushIfNeeded
+{
+  if (_flags.pendingFlush) {
+    return;
+  }
+
+  _flags.pendingFlush = YES;
+  [self performSelectorOnMainThread:@selector(flushNow) withObject:nil waitUntilDone:NO modes:@[ NSRunLoopCommonModes ]];
+}
+
+- (void)flushNow
+{
+  ASDN::MutexLocker l(_lock);
+  for (__unused ASDisplayNode *node in _dirtyNodes) {
+    // TODO: apply pending state.
+  }
+  [_dirtyNodes removeAllObjects];
+  _flags.pendingFlush = NO;
+}
+
+@end
+
+@implementation ASPendingStateController (Testing)
+
+- (BOOL)test_isFlushScheduled
+{
+  return _flags.pendingFlush;
+}
+
+@end

AsyncDisplayKit/Private/ASWeakSet.h

@@ -0,0 +1,40 @@
+//
+//  ASWeakSet.h
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 1/7/16.
+//  Copyright © 2016 Facebook. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface ASWeakSet<__covariant ObjectType> : NSObject<NSFastEnumeration>
+
+/// Returns YES if the receiver is empty, NO otherwise.
+@property (nonatomic, readonly, getter=isEmpty) BOOL empty;
+
+/// Returns YES if `object` is in the receiver, NO otherwise.
+- (BOOL)containsObject:(ObjectType)object;
+
+/// Insets `object` into the set.
+- (void)addObject:(ObjectType)object;
+
+/// Removes object from the set.
+- (void)removeObject:(ObjectType)object;
+
+/// Removes all objects from the set.
+- (void)removeAllObjects;
+
+/**
+ How many objects are contained in this set.
+ 
+ NOTE: This method is O(N). Consider using the `empty`
+ property.
+ */
+@property (nonatomic, readonly) NSUInteger count;
+
+@end
+
+NS_ASSUME_NONNULL_END

AsyncDisplayKit/Private/ASWeakSet.m

@@ -0,0 +1,68 @@
+//
+//  ASWeakSet.m
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 1/7/16.
+//  Copyright © 2016 Facebook. All rights reserved.
+//
+
+#import "ASWeakSet.h"
+
+@interface ASWeakSet<__covariant ObjectType> ()
+@property (nonatomic, strong, readonly) NSMapTable<NSNull *, NSNull *> *mapTable;
+@end
+
+@implementation ASWeakSet
+
+- (instancetype)init
+{
+  self = [super init];
+  if (self) {
+    _mapTable = [NSMapTable weakToStrongObjectsMapTable];
+  }
+  return self;
+}
+
+- (void)addObject:(id)object
+{
+  [_mapTable setObject:[NSNull null] forKey:object];
+}
+
+- (void)removeObject:(id)object
+{
+  [_mapTable removeObjectForKey:object];
+}
+
+- (void)removeAllObjects
+{
+  [_mapTable removeAllObjects];
+}
+
+- (BOOL)containsObject:(id)object
+{
+  return [_mapTable objectForKey:object] != nil;
+}
+
+- (BOOL)isEmpty
+{
+  for (__unused id object in _mapTable) {
+    return NO;
+  }
+  return YES;
+}
+
+- (NSUInteger)count
+{
+  NSInteger count = 0;
+  for (__unused id object in _mapTable) {
+    count += 1;
+  }
+  return count;
+}
+
+- (NSUInteger)countByEnumeratingWithState:(NSFastEnumerationState *)state objects:(__unsafe_unretained id  _Nonnull *)buffer count:(NSUInteger)len
+{
+  return [_mapTable countByEnumeratingWithState:state objects:buffer count:len];
+}
+
+@end

AsyncDisplayKit/Private/_ASPendingState.h

@@ -30,4 +30,8 @@
 + (_ASPendingState *)pendingViewStateFromLayer:(CALayer *)layer;
 + (_ASPendingState *)pendingViewStateFromView:(UIView *)view;
 
+@property (nonatomic, readonly) BOOL hasChanges;
+
+- (void)clearChanges;
+
 @end

AsyncDisplayKit/Private/_ASPendingState.m

@@ -12,6 +12,57 @@
 #import "_ASAsyncTransactionContainer.h"
 #import "ASAssert.h"
 
+typedef struct {
+  // Properties
+  int needsDisplay:1;
+  int needsLayout:1;
+
+  // Flags indicating that a given property should be applied to the view at creation
+  int setClipsToBounds:1;
+  int setOpaque:1;
+  int setNeedsDisplayOnBoundsChange:1;
+  int setAutoresizesSubviews:1;
+  int setAutoresizingMask:1;
+  int setFrame:1;
+  int setBounds:1;
+  int setBackgroundColor:1;
+  int setTintColor:1;
+  int setContents:1;
+  int setHidden:1;
+  int setAlpha:1;
+  int setCornerRadius:1;
+  int setContentMode:1;
+  int setNeedsDisplay:1;
+  int setAnchorPoint:1;
+  int setPosition:1;
+  int setZPosition:1;
+  int setContentsScale:1;
+  int setTransform:1;
+  int setSublayerTransform:1;
+  int setUserInteractionEnabled:1;
+  int setExclusiveTouch:1;
+  int setShadowColor:1;
+  int setShadowOpacity:1;
+  int setShadowOffset:1;
+  int setShadowRadius:1;
+  int setBorderWidth:1;
+  int setBorderColor:1;
+  int setAsyncTransactionContainer:1;
+  int setAllowsEdgeAntialiasing:1;
+  int setEdgeAntialiasingMask:1;
+  int setIsAccessibilityElement:1;
+  int setAccessibilityLabel:1;
+  int setAccessibilityHint:1;
+  int setAccessibilityValue:1;
+  int setAccessibilityTraits:1;
+  int setAccessibilityFrame:1;
+  int setAccessibilityLanguage:1;
+  int setAccessibilityElementsHidden:1;
+  int setAccessibilityViewIsModal:1;
+  int setShouldGroupAccessibilityChildren:1;
+  int setAccessibilityIdentifier:1;
+} ASPendingStateFlags;
+
 @implementation _ASPendingState
 {
   @package //Expose all ivars for ASDisplayNode to bypass getters for efficiency
@@ -50,56 +101,7 @@
   BOOL shouldGroupAccessibilityChildren;
   NSString *accessibilityIdentifier;
 
-  struct {
+  ASPendingStateFlags _flags;
-    // Properties
-    int needsDisplay:1;
-    int needsLayout:1;
-
-    // Flags indicating that a given property should be applied to the view at creation
-    int setClipsToBounds:1;
-    int setOpaque:1;
-    int setNeedsDisplayOnBoundsChange:1;
-    int setAutoresizesSubviews:1;
-    int setAutoresizingMask:1;
-    int setFrame:1;
-    int setBounds:1;
-    int setBackgroundColor:1;
-    int setTintColor:1;
-    int setContents:1;
-    int setHidden:1;
-    int setAlpha:1;
-    int setCornerRadius:1;
-    int setContentMode:1;
-    int setNeedsDisplay:1;
-    int setAnchorPoint:1;
-    int setPosition:1;
-    int setZPosition:1;
-    int setContentsScale:1;
-    int setTransform:1;
-    int setSublayerTransform:1;
-    int setUserInteractionEnabled:1;
-    int setExclusiveTouch:1;
-    int setShadowColor:1;
-    int setShadowOpacity:1;
-    int setShadowOffset:1;
-    int setShadowRadius:1;
-    int setBorderWidth:1;
-    int setBorderColor:1;
-    int setAsyncTransactionContainer:1;
-    int setAllowsEdgeAntialiasing:1;
-    int setEdgeAntialiasingMask:1;
-    int setIsAccessibilityElement:1;
-    int setAccessibilityLabel:1;
-    int setAccessibilityHint:1;
-    int setAccessibilityValue:1;
-    int setAccessibilityTraits:1;
-    int setAccessibilityFrame:1;
-    int setAccessibilityLanguage:1;
-    int setAccessibilityElementsHidden:1;
-    int setAccessibilityViewIsModal:1;
-    int setShouldGroupAccessibilityChildren:1;
-    int setAccessibilityIdentifier:1;
-  } _flags;
 }
 
 
@@ -199,12 +201,6 @@ static UIColor *defaultTintColor = nil;
   return self;
 }
 
-- (CALayer *)layer
-{
-  ASDisplayNodeAssert(NO, @"One shouldn't call node.layer when the view isn't loaded, but we're returning nil to not crash if someone is still doing this");
-  return nil;
-}
-
 - (void)setNeedsDisplay
 {
   _flags.needsDisplay = YES;
@@ -560,91 +556,92 @@ static UIColor *defaultTintColor = nil;
 
 - (void)applyToLayer:(CALayer *)layer
 {
-  if (_flags.setAnchorPoint)
+  ASPendingStateFlags flags = _flags;
+  if (flags.setAnchorPoint)
     layer.anchorPoint = anchorPoint;
 
-  if (_flags.setPosition)
+  if (flags.setPosition)
     layer.position = position;
 
-  if (_flags.setZPosition)
+  if (flags.setZPosition)
     layer.zPosition = zPosition;
 
-  if (_flags.setBounds)
+  if (flags.setBounds)
     layer.bounds = bounds;
 
-  if (_flags.setContentsScale)
+  if (flags.setContentsScale)
     layer.contentsScale = contentsScale;
 
-  if (_flags.setTransform)
+  if (flags.setTransform)
     layer.transform = transform;
 
-  if (_flags.setSublayerTransform)
+  if (flags.setSublayerTransform)
     layer.sublayerTransform = sublayerTransform;
 
-  if (_flags.setContents)
+  if (flags.setContents)
     layer.contents = contents;
 
-  if (_flags.setClipsToBounds)
+  if (flags.setClipsToBounds)
     layer.masksToBounds = clipsToBounds;
 
-  if (_flags.setBackgroundColor)
+  if (flags.setBackgroundColor)
     layer.backgroundColor = backgroundColor;
 
-  if (_flags.setOpaque)
+  if (flags.setOpaque)
     layer.opaque = opaque;
 
-  if (_flags.setHidden)
+  if (flags.setHidden)
     layer.hidden = isHidden;
 
-  if (_flags.setAlpha)
+  if (flags.setAlpha)
     layer.opacity = alpha;
 
-  if (_flags.setCornerRadius)
+  if (flags.setCornerRadius)
     layer.cornerRadius = cornerRadius;
 
-  if (_flags.setContentMode)
+  if (flags.setContentMode)
     layer.contentsGravity = ASDisplayNodeCAContentsGravityFromUIContentMode(contentMode);
 
-  if (_flags.setShadowColor)
+  if (flags.setShadowColor)
     layer.shadowColor = shadowColor;
 
-  if (_flags.setShadowOpacity)
+  if (flags.setShadowOpacity)
     layer.shadowOpacity = shadowOpacity;
 
-  if (_flags.setShadowOffset)
+  if (flags.setShadowOffset)
     layer.shadowOffset = shadowOffset;
 
-  if (_flags.setShadowRadius)
+  if (flags.setShadowRadius)
     layer.shadowRadius = shadowRadius;
 
-  if (_flags.setBorderWidth)
+  if (flags.setBorderWidth)
     layer.borderWidth = borderWidth;
 
-  if (_flags.setBorderColor)
+  if (flags.setBorderColor)
     layer.borderColor = borderColor;
 
-  if (_flags.setNeedsDisplayOnBoundsChange)
+  if (flags.setNeedsDisplayOnBoundsChange)
     layer.needsDisplayOnBoundsChange = needsDisplayOnBoundsChange;
 
-  if (_flags.setAllowsEdgeAntialiasing)
+  if (flags.setAllowsEdgeAntialiasing)
     layer.allowsEdgeAntialiasing = allowsEdgeAntialiasing;
 
-  if (_flags.setEdgeAntialiasingMask)
+  if (flags.setEdgeAntialiasingMask)
     layer.edgeAntialiasingMask = edgeAntialiasingMask;
 
-  if (_flags.needsDisplay)
+  if (flags.needsDisplay)
     [layer setNeedsDisplay];
 
-  if (_flags.needsLayout)
+  if (flags.needsLayout)
     [layer setNeedsLayout];
 
-  if (_flags.setAsyncTransactionContainer)
+  if (flags.setAsyncTransactionContainer)
     layer.asyncdisplaykit_asyncTransactionContainer = asyncTransactionContainer;
 
-  if (_flags.setOpaque)
+  if (flags.setOpaque)
     ASDisplayNodeAssert(layer.opaque == opaque, @"Didn't set opaque as desired");
   
-  if (_flags.setFrame)
+  if (flags.setFrame)
     ASDisplayNodeAssert(NO, @"Frame property should only be used for synchronously wrapped nodes.  See setFrame: in ASDisplayNode+UIViewBridge");
 }
 
@@ -660,143 +657,144 @@ static UIColor *defaultTintColor = nil;
 
   CALayer *layer = view.layer;
 
-  if (_flags.setAnchorPoint)
+  ASPendingStateFlags flags = _flags;
+  if (flags.setAnchorPoint)
     layer.anchorPoint = anchorPoint;
 
-  if (_flags.setPosition)
+  if (flags.setPosition)
     layer.position = position;
 
-  if (_flags.setZPosition)
+  if (flags.setZPosition)
     layer.zPosition = zPosition;
 
   // This should only be used for synchronous views wrapped by nodes.
-  if (_flags.setFrame && !(_flags.setBounds && _flags.setPosition)) {
+  if (flags.setFrame && !(flags.setBounds && flags.setPosition)) {
     view.frame = frame;
   }
   
-  if (_flags.setBounds)
+  if (flags.setBounds)
     view.bounds = bounds;
 
-  if (_flags.setContentsScale)
+  if (flags.setContentsScale)
     layer.contentsScale = contentsScale;
 
-  if (_flags.setTransform)
+  if (flags.setTransform)
     layer.transform = transform;
 
-  if (_flags.setSublayerTransform)
+  if (flags.setSublayerTransform)
     layer.sublayerTransform = sublayerTransform;
 
-  if (_flags.setContents)
+  if (flags.setContents)
     layer.contents = contents;
 
-  if (_flags.setClipsToBounds)
+  if (flags.setClipsToBounds)
     view.clipsToBounds = clipsToBounds;
 
-  if (_flags.setBackgroundColor)
+  if (flags.setBackgroundColor)
     layer.backgroundColor = backgroundColor;
 
-  if (_flags.setTintColor)
+  if (flags.setTintColor)
     view.tintColor = self.tintColor;
 
-  if (_flags.setOpaque)
+  if (flags.setOpaque)
     view.layer.opaque = opaque;
 
-  if (_flags.setHidden)
+  if (flags.setHidden)
     view.hidden = isHidden;
 
-  if (_flags.setAlpha)
+  if (flags.setAlpha)
     view.alpha = alpha;
 
-  if (_flags.setCornerRadius)
+  if (flags.setCornerRadius)
     layer.cornerRadius = cornerRadius;
 
-  if (_flags.setContentMode)
+  if (flags.setContentMode)
     view.contentMode = contentMode;
 
-  if (_flags.setUserInteractionEnabled)
+  if (flags.setUserInteractionEnabled)
     view.userInteractionEnabled = userInteractionEnabled;
 
   #if TARGET_OS_IOS
-  if (_flags.setExclusiveTouch)
+  if (flags.setExclusiveTouch)
     view.exclusiveTouch = exclusiveTouch;
   #endif
     
-  if (_flags.setShadowColor)
+  if (flags.setShadowColor)
     layer.shadowColor = shadowColor;
 
-  if (_flags.setShadowOpacity)
+  if (flags.setShadowOpacity)
     layer.shadowOpacity = shadowOpacity;
 
-  if (_flags.setShadowOffset)
+  if (flags.setShadowOffset)
     layer.shadowOffset = shadowOffset;
 
-  if (_flags.setShadowRadius)
+  if (flags.setShadowRadius)
     layer.shadowRadius = shadowRadius;
 
-  if (_flags.setBorderWidth)
+  if (flags.setBorderWidth)
     layer.borderWidth = borderWidth;
 
-  if (_flags.setBorderColor)
+  if (flags.setBorderColor)
     layer.borderColor = borderColor;
 
-  if (_flags.setAutoresizingMask)
+  if (flags.setAutoresizingMask)
     view.autoresizingMask = autoresizingMask;
 
-  if (_flags.setAutoresizesSubviews)
+  if (flags.setAutoresizesSubviews)
     view.autoresizesSubviews = autoresizesSubviews;
 
-  if (_flags.setNeedsDisplayOnBoundsChange)
+  if (flags.setNeedsDisplayOnBoundsChange)
     layer.needsDisplayOnBoundsChange = needsDisplayOnBoundsChange;
 
-  if (_flags.setAllowsEdgeAntialiasing)
+  if (flags.setAllowsEdgeAntialiasing)
     layer.allowsEdgeAntialiasing = allowsEdgeAntialiasing;
 
-  if (_flags.setEdgeAntialiasingMask)
+  if (flags.setEdgeAntialiasingMask)
     layer.edgeAntialiasingMask = edgeAntialiasingMask;
 
-  if (_flags.needsDisplay)
+  if (flags.needsDisplay)
     [view setNeedsDisplay];
 
-  if (_flags.needsLayout)
+  if (flags.needsLayout)
     [view setNeedsLayout];
 
-  if (_flags.setAsyncTransactionContainer)
+  if (flags.setAsyncTransactionContainer)
     view.asyncdisplaykit_asyncTransactionContainer = asyncTransactionContainer;
 
-  if (_flags.setOpaque)
+  if (flags.setOpaque)
     ASDisplayNodeAssert(view.layer.opaque == opaque, @"Didn't set opaque as desired");
 
-  if (_flags.setIsAccessibilityElement)
+  if (flags.setIsAccessibilityElement)
     view.isAccessibilityElement = isAccessibilityElement;
 
-  if (_flags.setAccessibilityLabel)
+  if (flags.setAccessibilityLabel)
     view.accessibilityLabel = accessibilityLabel;
 
-  if (_flags.setAccessibilityHint)
+  if (flags.setAccessibilityHint)
     view.accessibilityHint = accessibilityHint;
 
-  if (_flags.setAccessibilityValue)
+  if (flags.setAccessibilityValue)
     view.accessibilityValue = accessibilityValue;
 
-  if (_flags.setAccessibilityTraits)
+  if (flags.setAccessibilityTraits)
     view.accessibilityTraits = accessibilityTraits;
 
-  if (_flags.setAccessibilityFrame)
+  if (flags.setAccessibilityFrame)
     view.accessibilityFrame = accessibilityFrame;
 
-  if (_flags.setAccessibilityLanguage)
+  if (flags.setAccessibilityLanguage)
     view.accessibilityLanguage = accessibilityLanguage;
 
-  if (_flags.setAccessibilityElementsHidden)
+  if (flags.setAccessibilityElementsHidden)
     view.accessibilityElementsHidden = accessibilityElementsHidden;
 
-  if (_flags.setAccessibilityViewIsModal)
+  if (flags.setAccessibilityViewIsModal)
     view.accessibilityViewIsModal = accessibilityViewIsModal;
 
-  if (_flags.setShouldGroupAccessibilityChildren)
+  if (flags.setShouldGroupAccessibilityChildren)
     view.shouldGroupAccessibilityChildren = shouldGroupAccessibilityChildren;
 
-  if (_flags.setAccessibilityIdentifier)
+  if (flags.setAccessibilityIdentifier)
     view.accessibilityIdentifier = accessibilityIdentifier;
 }
 
@@ -806,81 +804,31 @@ static UIColor *defaultTintColor = nil;
   if (!layer) {
     return nil;
   }
-  
   _ASPendingState *pendingState = [[_ASPendingState alloc] init];
-  
   pendingState.anchorPoint = layer.anchorPoint;
-  (pendingState->_flags).setAnchorPoint = YES;
-  
   pendingState.position = layer.position;
-  (pendingState->_flags).setPosition = YES;
-  
   pendingState.zPosition = layer.zPosition;
-  (pendingState->_flags).setZPosition = YES;
-  
   pendingState.bounds = layer.bounds;
-  (pendingState->_flags).setBounds = YES;
-  
   pendingState.contentsScale = layer.contentsScale;
-  (pendingState->_flags).setContentsScale = YES;
-  
   pendingState.transform = layer.transform;
-  (pendingState->_flags).setTransform = YES;
-  
   pendingState.sublayerTransform = layer.sublayerTransform;
-  (pendingState->_flags).setSublayerTransform = YES;
-  
   pendingState.contents = layer.contents;
-  (pendingState->_flags).setContents = YES;
-  
   pendingState.clipsToBounds = layer.masksToBounds;
-  (pendingState->_flags).setClipsToBounds = YES;
-  
   pendingState.backgroundColor = layer.backgroundColor;
-  (pendingState->_flags).setBackgroundColor = YES;
-  
   pendingState.opaque = layer.opaque;
-  (pendingState->_flags).setOpaque = YES;
-  
   pendingState.hidden = layer.hidden;
-  (pendingState->_flags).setHidden = YES;
-  
   pendingState.alpha = layer.opacity;
-  (pendingState->_flags).setAlpha = YES;
-  
   pendingState.cornerRadius = layer.cornerRadius;
-  (pendingState->_flags).setCornerRadius = YES;
-  
   pendingState.contentMode = ASDisplayNodeUIContentModeFromCAContentsGravity(layer.contentsGravity);
-  (pendingState->_flags).setContentMode = YES;
-  
   pendingState.shadowColor = layer.shadowColor;
-  (pendingState->_flags).setShadowColor = YES;
-  
   pendingState.shadowOpacity = layer.shadowOpacity;
-  (pendingState->_flags).setShadowOpacity = YES;
-  
   pendingState.shadowOffset = layer.shadowOffset;
-  (pendingState->_flags).setShadowOffset = YES;
-  
   pendingState.shadowRadius = layer.shadowRadius;
-  (pendingState->_flags).setShadowRadius = YES;
-  
   pendingState.borderWidth = layer.borderWidth;
-  (pendingState->_flags).setBorderWidth = YES;
-  
   pendingState.borderColor = layer.borderColor;
-  (pendingState->_flags).setBorderColor = YES;
-  
   pendingState.needsDisplayOnBoundsChange = layer.needsDisplayOnBoundsChange;
-  (pendingState->_flags).setNeedsDisplayOnBoundsChange = YES;
-  
   pendingState.allowsEdgeAntialiasing = layer.allowsEdgeAntialiasing;
-  (pendingState->_flags).setAllowsEdgeAntialiasing = YES;
-  
   pendingState.edgeAntialiasingMask = layer.edgeAntialiasingMask;
-  (pendingState->_flags).setEdgeAntialiasingMask = YES;
-  
   return pendingState;
 }
 
@@ -890,134 +838,110 @@ static UIColor *defaultTintColor = nil;
   if (!view) {
     return nil;
   }
-  
   _ASPendingState *pendingState = [[_ASPendingState alloc] init];
-  
+
   CALayer *layer = view.layer;
-  
   pendingState.anchorPoint = layer.anchorPoint;
-  (pendingState->_flags).setAnchorPoint = YES;
-  
   pendingState.position = layer.position;
-  (pendingState->_flags).setPosition = YES;
-  
   pendingState.zPosition = layer.zPosition;
-  (pendingState->_flags).setZPosition = YES;
-  
   pendingState.bounds = view.bounds;
-  (pendingState->_flags).setBounds = YES;
-  
   pendingState.contentsScale = layer.contentsScale;
-  (pendingState->_flags).setContentsScale = YES;
-  
   pendingState.transform = layer.transform;
-  (pendingState->_flags).setTransform = YES;
-  
   pendingState.sublayerTransform = layer.sublayerTransform;
-  (pendingState->_flags).setSublayerTransform = YES;
-  
   pendingState.contents = layer.contents;
-  (pendingState->_flags).setContents = YES;
-  
   pendingState.clipsToBounds = view.clipsToBounds;
-  (pendingState->_flags).setClipsToBounds = YES;
-  
   pendingState.backgroundColor = layer.backgroundColor;
-  (pendingState->_flags).setBackgroundColor = YES;
-  
   pendingState.tintColor = view.tintColor;
-  (pendingState->_flags).setTintColor = YES;
-  
   pendingState.opaque = layer.opaque;
-  (pendingState->_flags).setOpaque = YES;
-  
   pendingState.hidden = view.hidden;
-  (pendingState->_flags).setHidden = YES;
-  
   pendingState.alpha = view.alpha;
-  (pendingState->_flags).setAlpha = YES;
-  
   pendingState.cornerRadius = layer.cornerRadius;
-  (pendingState->_flags).setCornerRadius = YES;
-  
   pendingState.contentMode = view.contentMode;
-  (pendingState->_flags).setContentMode = YES;
-  
   pendingState.userInteractionEnabled = view.userInteractionEnabled;
-  (pendingState->_flags).setUserInteractionEnabled = YES;
 #if TARGET_OS_IOS
   pendingState.exclusiveTouch = view.exclusiveTouch;
-  (pendingState->_flags).setExclusiveTouch = YES;
 #endif
   pendingState.shadowColor = layer.shadowColor;
-  (pendingState->_flags).setShadowColor = YES;
-  
   pendingState.shadowOpacity = layer.shadowOpacity;
-  (pendingState->_flags).setShadowOpacity = YES;
-  
   pendingState.shadowOffset = layer.shadowOffset;
-  (pendingState->_flags).setShadowOffset = YES;
-  
   pendingState.shadowRadius = layer.shadowRadius;
-  (pendingState->_flags).setShadowRadius = YES;
-  
   pendingState.borderWidth = layer.borderWidth;
-  (pendingState->_flags).setBorderWidth = YES;
-  
   pendingState.borderColor = layer.borderColor;
-  (pendingState->_flags).setBorderColor = YES;
-  
   pendingState.autoresizingMask = view.autoresizingMask;
-  (pendingState->_flags).setAutoresizingMask = YES;
-  
   pendingState.autoresizesSubviews = view.autoresizesSubviews;
-  (pendingState->_flags).setAutoresizesSubviews = YES;
-  
   pendingState.needsDisplayOnBoundsChange = layer.needsDisplayOnBoundsChange;
-  (pendingState->_flags).setNeedsDisplayOnBoundsChange = YES;
-  
   pendingState.allowsEdgeAntialiasing = layer.allowsEdgeAntialiasing;
-  (pendingState->_flags).setAllowsEdgeAntialiasing = YES;
-  
   pendingState.edgeAntialiasingMask = layer.edgeAntialiasingMask;
-  (pendingState->_flags).setEdgeAntialiasingMask = YES;
-
   pendingState.isAccessibilityElement = view.isAccessibilityElement;
-  (pendingState->_flags).setIsAccessibilityElement = YES;
-  
   pendingState.accessibilityLabel = view.accessibilityLabel;
-  (pendingState->_flags).setAccessibilityLabel = YES;
-  
   pendingState.accessibilityHint = view.accessibilityHint;
-  (pendingState->_flags).setAccessibilityHint = YES;
-  
   pendingState.accessibilityValue = view.accessibilityValue;
-  (pendingState->_flags).setAccessibilityValue = YES;
-  
   pendingState.accessibilityTraits = view.accessibilityTraits;
-  (pendingState->_flags).setAccessibilityTraits = YES;
-  
   pendingState.accessibilityFrame = view.accessibilityFrame;
-  (pendingState->_flags).setAccessibilityFrame = YES;
-  
   pendingState.accessibilityLanguage = view.accessibilityLanguage;
-  (pendingState->_flags).setAccessibilityLanguage = YES;
-  
   pendingState.accessibilityElementsHidden = view.accessibilityElementsHidden;
-  (pendingState->_flags).setAccessibilityElementsHidden = YES;
-  
   pendingState.accessibilityViewIsModal = view.accessibilityViewIsModal;
-  (pendingState->_flags).setAccessibilityViewIsModal = YES;
-  
   pendingState.shouldGroupAccessibilityChildren = view.shouldGroupAccessibilityChildren;
-  (pendingState->_flags).setShouldGroupAccessibilityChildren = YES;
-  
   pendingState.accessibilityIdentifier = view.accessibilityIdentifier;
-  (pendingState->_flags).setAccessibilityIdentifier = YES;
-  
   return pendingState;
 }
 
+- (void)clearChanges
+{
+  _flags = (ASPendingStateFlags){ 0 };
+}
+
+- (BOOL)hasChanges
+{
+  ASPendingStateFlags flags = _flags;
+
+  return (flags.setAnchorPoint
+  || flags.setPosition
+  || flags.setZPosition
+  || flags.setFrame
+  || flags.setBounds
+  || flags.setPosition
+  || flags.setContentsScale
+  || flags.setTransform
+  || flags.setSublayerTransform
+  || flags.setContents
+  || flags.setClipsToBounds
+  || flags.setBackgroundColor
+  || flags.setTintColor
+  || flags.setHidden
+  || flags.setAlpha
+  || flags.setCornerRadius
+  || flags.setContentMode
+  || flags.setUserInteractionEnabled
+  || flags.setExclusiveTouch
+  || flags.setShadowOpacity
+  || flags.setShadowOffset
+  || flags.setShadowRadius
+  || flags.setShadowColor
+  || flags.setBorderWidth
+  || flags.setBorderColor
+  || flags.setAutoresizingMask
+  || flags.setAutoresizesSubviews
+  || flags.setNeedsDisplayOnBoundsChange
+  || flags.setAllowsEdgeAntialiasing
+  || flags.setEdgeAntialiasingMask
+  || flags.needsDisplay
+  || flags.needsLayout
+  || flags.setAsyncTransactionContainer
+  || flags.setOpaque
+  || flags.setIsAccessibilityElement
+  || flags.setAccessibilityLabel
+  || flags.setAccessibilityHint
+  || flags.setAccessibilityValue
+  || flags.setAccessibilityTraits
+  || flags.setAccessibilityFrame
+  || flags.setAccessibilityLanguage
+  || flags.setAccessibilityElementsHidden
+  || flags.setAccessibilityViewIsModal
+  || flags.setShouldGroupAccessibilityChildren
+  || flags.setAccessibilityIdentifier);
+}
+
 - (void)dealloc
 {
   CGColorRelease(backgroundColor);

AsyncDisplayKitTests/ASPendingStateControllerTests.m

@@ -0,0 +1,40 @@
+//
+//  ASPendingStateControllerTests.m
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 1/7/16.
+//  Copyright © 2016 Facebook. All rights reserved.
+//
+
+#import <XCTest/XCTest.h>
+#import "ASPendingStateController.h"
+#import "ASDisplayNode.h"
+
+@interface ASPendingStateController (Testing)
+- (BOOL)test_isFlushScheduled;
+@end
+
+@interface ASPendingStateControllerTests : XCTestCase
+
+@end
+
+@implementation ASPendingStateControllerTests
+
+- (void)testTheresASharedInstance
+{
+  XCTAssertNotNil([ASPendingStateController sharedInstance]);
+}
+
+- (void)testThatRegisteringANodeCausesAtFlushAtRunLoopEnd
+{
+  ASPendingStateController *ctrl = [ASPendingStateController sharedInstance];
+  ASDisplayNode *node = [ASDisplayNode new];
+  XCTAssertFalse(ctrl.test_isFlushScheduled);
+  [ctrl registerNode:node];
+  XCTAssertTrue(ctrl.test_isFlushScheduled);
+  NSDate *timeout = [NSDate dateWithTimeIntervalSinceNow:1];
+  [[NSRunLoop mainRunLoop] runMode:NSDefaultRunLoopMode beforeDate:timeout];
+  XCTAssertFalse(ctrl.test_isFlushScheduled);
+}
+
+@end

AsyncDisplayKitTests/ASWeakSetTests.m

@@ -0,0 +1,134 @@
+//
+//  ASWeakSetTests.m
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 1/7/16.
+//  Copyright © 2016 Facebook. All rights reserved.
+//
+
+#import <XCTest/XCTest.h>
+#import "ASWeakSet.h"
+
+@interface ASWeakSetTests : XCTestCase
+
+@end
+
+@implementation ASWeakSetTests
+
+- (void)testAddingACoupleRetainedObjects
+{
+  ASWeakSet <NSString *> *weakSet = [ASWeakSet new];
+  NSString *hello = @"hello";
+  NSString *world = @"hello";
+  [weakSet addObject:hello];
+  [weakSet addObject:world];
+  XCTAssert([weakSet containsObject:hello]);
+  XCTAssert([weakSet containsObject:world]);
+  XCTAssert(![weakSet containsObject:@"apple"]);
+}
+
+- (void)testThatCountIncorporatesDeallocatedObjects
+{
+  ASWeakSet *weakSet = [ASWeakSet new];
+  XCTAssertEqual(weakSet.count, 0);
+  NSObject *a = [NSObject new];
+  NSObject *b = [NSObject new];
+  [weakSet addObject:a];
+  [weakSet addObject:b];
+  XCTAssertEqual(weakSet.count, 2);
+
+  @autoreleasepool {
+    NSObject *doomedObject = [NSObject new];
+    [weakSet addObject:doomedObject];
+    XCTAssertEqual(weakSet.count, 3);
+  }
+
+  XCTAssertEqual(weakSet.count, 2);
+}
+
+- (void)testThatIsEmptyIncorporatesDeallocatedObjects
+{
+  ASWeakSet *weakSet = [ASWeakSet new];
+  XCTAssertTrue(weakSet.isEmpty);
+  @autoreleasepool {
+    NSObject *doomedObject = [NSObject new];
+    [weakSet addObject:doomedObject];
+    XCTAssertFalse(weakSet.isEmpty);
+  }
+  XCTAssertTrue(weakSet.isEmpty);
+}
+
+- (void)testThatContainsObjectWorks
+{
+  ASWeakSet *weakSet = [ASWeakSet new];
+  NSObject *a = [NSObject new];
+  NSObject *b = [NSObject new];
+  [weakSet addObject:a];
+  XCTAssertTrue([weakSet containsObject:a]);
+  XCTAssertFalse([weakSet containsObject:b]);
+}
+
+- (void)testThatRemoveObjectWorks
+{
+  ASWeakSet *weakSet = [ASWeakSet new];
+  NSObject *a = [NSObject new];
+  NSObject *b = [NSObject new];
+  [weakSet addObject:a];
+  [weakSet addObject:b];
+  XCTAssertTrue([weakSet containsObject:a]);
+  XCTAssertTrue([weakSet containsObject:b]);
+  XCTAssertEqual(weakSet.count, 2);
+
+  [weakSet removeObject:b];
+  XCTAssertTrue([weakSet containsObject:a]);
+  XCTAssertFalse([weakSet containsObject:b]);
+  XCTAssertEqual(weakSet.count, 1);
+}
+
+- (void)testThatFastEnumerationWorks
+{
+  ASWeakSet *weakSet = [ASWeakSet new];
+  NSObject *a = [NSObject new];
+  NSObject *b = [NSObject new];
+  [weakSet addObject:a];
+  [weakSet addObject:b];
+
+  @autoreleasepool {
+    NSObject *doomedObject = [NSObject new];
+    [weakSet addObject:doomedObject];
+    XCTAssertEqual(weakSet.count, 3);
+  }
+
+  NSInteger i = 0;
+  NSMutableSet *awaitingObjects = [NSMutableSet setWithObjects:a, b, nil];
+  for (NSObject *object in weakSet) {
+    XCTAssertTrue([awaitingObjects containsObject:object]);
+    [awaitingObjects removeObject:object];
+    i += 1;
+  }
+
+  XCTAssertEqual(i, 2);
+}
+
+- (void)testThatRemoveAllObjectsWorks
+{
+  ASWeakSet *weakSet = [ASWeakSet new];
+  NSObject *a = [NSObject new];
+  NSObject *b = [NSObject new];
+  [weakSet addObject:a];
+  [weakSet addObject:b];
+  XCTAssertEqual(weakSet.count, 2);
+
+  [weakSet removeAllObjects];
+
+  XCTAssertEqual(weakSet.count, 0);
+
+  NSInteger i = 0;
+  for (__unused NSObject *object in weakSet) {
+    i += 1;
+  }
+
+  XCTAssertEqual(i, 0);
+}
+
+@end