Add unit tests for the layout engine (TextureGroup#424)

* Build testing platform & tests for the layout engine

* Add our license header to debugbreak.

* Remove thing

* Address review comments

* Beef up the logging

* Update -[ASLayout isEqual:]

* testLayoutTransitionWithAsyncMeasurement passes now

* Disable testASetNeedsLayoutInterferingWithTheCurrentTransition

* Fix build errors

AsyncDisplayKit.xcodeproj/project.pbxproj

@@ -405,6 +405,9 @@
 		CCCCCCE81EC3F0FC0087FE10 /* NSAttributedString+ASText.m in Sources */ = {isa = PBXBuildFile; fileRef = CCCCCCE61EC3F0FC0087FE10 /* NSAttributedString+ASText.m */; };
 		CCDD148B1EEDCD9D0020834E /* ASCollectionModernDataSourceTests.m in Sources */ = {isa = PBXBuildFile; fileRef = CCDD148A1EEDCD9D0020834E /* ASCollectionModernDataSourceTests.m */; };
 		CCE4F9B31F0D60AC00062E4E /* ASIntegerMapTests.m in Sources */ = {isa = PBXBuildFile; fileRef = CCE4F9B21F0D60AC00062E4E /* ASIntegerMapTests.m */; };
+		CCE4F9B51F0DA4F300062E4E /* ASLayoutEngineTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = CCE4F9B41F0DA4F300062E4E /* ASLayoutEngineTests.mm */; };
+		CCE4F9BA1F0DBB5000062E4E /* ASLayoutTestNode.mm in Sources */ = {isa = PBXBuildFile; fileRef = CCE4F9B71F0DBA5000062E4E /* ASLayoutTestNode.mm */; };
+		CCE4F9BE1F0ECE5200062E4E /* ASTLayoutFixture.mm in Sources */ = {isa = PBXBuildFile; fileRef = CCE4F9BD1F0ECE5200062E4E /* ASTLayoutFixture.mm */; };
 		CCF18FF41D2575E300DF5895 /* NSIndexSet+ASHelpers.h in Headers */ = {isa = PBXBuildFile; fileRef = CC4981BA1D1C7F65004E13CC /* NSIndexSet+ASHelpers.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		DB55C2671C641AE4004EDCF5 /* ASContextTransitioning.h in Headers */ = {isa = PBXBuildFile; fileRef = DB55C2651C641AE4004EDCF5 /* ASContextTransitioning.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		DB7121BCD50849C498C886FB /* libPods-AsyncDisplayKitTests.a in Frameworks */ = {isa = PBXBuildFile; fileRef = EFA731F0396842FF8AB635EE /* libPods-AsyncDisplayKitTests.a */; };
@@ -899,6 +902,12 @@
 		CCE04B211E313EB9006AEBBB /* IGListAdapter+AsyncDisplayKit.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "IGListAdapter+AsyncDisplayKit.m"; sourceTree = "<group>"; };
 		CCE04B2B1E314A32006AEBBB /* ASSupplementaryNodeSource.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASSupplementaryNodeSource.h; sourceTree = "<group>"; };
 		CCE4F9B21F0D60AC00062E4E /* ASIntegerMapTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASIntegerMapTests.m; sourceTree = "<group>"; };
+		CCE4F9B41F0DA4F300062E4E /* ASLayoutEngineTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASLayoutEngineTests.mm; sourceTree = "<group>"; };
+		CCE4F9B61F0DBA5000062E4E /* ASLayoutTestNode.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASLayoutTestNode.h; sourceTree = "<group>"; };
+		CCE4F9B71F0DBA5000062E4E /* ASLayoutTestNode.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASLayoutTestNode.mm; sourceTree = "<group>"; };
+		CCE4F9BB1F0EA67F00062E4E /* debugbreak.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = debugbreak.h; sourceTree = "<group>"; };
+		CCE4F9BC1F0ECE5200062E4E /* ASTLayoutFixture.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASTLayoutFixture.h; sourceTree = "<group>"; };
+		CCE4F9BD1F0ECE5200062E4E /* ASTLayoutFixture.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASTLayoutFixture.mm; sourceTree = "<group>"; };
 		D3779BCFF841AD3EB56537ED /* Pods-AsyncDisplayKitTests.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-AsyncDisplayKitTests.release.xcconfig"; path = "Pods/Target Support Files/Pods-AsyncDisplayKitTests/Pods-AsyncDisplayKitTests.release.xcconfig"; sourceTree = "<group>"; };
 		D785F6601A74327E00291744 /* ASScrollNode.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASScrollNode.h; sourceTree = "<group>"; };
 		D785F6611A74327E00291744 /* ASScrollNode.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASScrollNode.mm; sourceTree = "<group>"; };
@@ -1175,6 +1184,11 @@
 				CC11F9791DB181180024D77B /* ASNetworkImageNodeTests.m */,
 				CC051F1E1D7A286A006434CB /* ASCALayerTests.m */,
 				CCE4F9B21F0D60AC00062E4E /* ASIntegerMapTests.m */,
+				CCE4F9B41F0DA4F300062E4E /* ASLayoutEngineTests.mm */,
+				CCE4F9B61F0DBA5000062E4E /* ASLayoutTestNode.h */,
+				CCE4F9B71F0DBA5000062E4E /* ASLayoutTestNode.mm */,
+				CCE4F9BC1F0ECE5200062E4E /* ASTLayoutFixture.h */,
+				CCE4F9BD1F0ECE5200062E4E /* ASTLayoutFixture.mm */,
 				CC8B05D71D73979700F54286 /* ASTextNodePerformanceTests.m */,
 				CC8B05D41D73836400F54286 /* ASPerformanceTestContext.h */,
 				CC8B05D51D73836400F54286 /* ASPerformanceTestContext.m */,
@@ -1573,6 +1587,7 @@
 		CC583ABF1EF9BAB400134156 /* Common */ = {
 			isa = PBXGroup;
 			children = (
+				CCE4F9BB1F0EA67F00062E4E /* debugbreak.h */,
 				CC583AC01EF9BAB400134156 /* ASDisplayNode+OCMock.m */,
 				CC583AC11EF9BAB400134156 /* ASTestCase.h */,
 				CC583AC21EF9BAB400134156 /* ASTestCase.m */,
@@ -2187,6 +2202,7 @@
 				ACF6ED611B178DC700DA7C62 /* ASOverlayLayoutSpecSnapshotTests.mm in Sources */,
 				CC8B05D61D73836400F54286 /* ASPerformanceTestContext.m in Sources */,
 				CC0AEEA41D66316E005D1C78 /* ASUICollectionViewTests.m in Sources */,
+				CCE4F9B51F0DA4F300062E4E /* ASLayoutEngineTests.mm in Sources */,
 				69B225671D72535E00B25B22 /* ASDisplayNodeLayoutTests.mm in Sources */,
 				ACF6ED621B178DC700DA7C62 /* ASRatioLayoutSpecSnapshotTests.mm in Sources */,
 				7AB338691C55B97B0055FDE8 /* ASRelativeLayoutSpecSnapshotTests.mm in Sources */,
@@ -2195,12 +2211,14 @@
 				254C6B541BF8FF2A003EC431 /* ASTextKitTests.mm in Sources */,
 				05EA6FE71AC0966E00E35788 /* ASSnapshotTestCase.m in Sources */,
 				ACF6ED631B178DC700DA7C62 /* ASStackLayoutSpecSnapshotTests.mm in Sources */,
+				CCE4F9BA1F0DBB5000062E4E /* ASLayoutTestNode.mm in Sources */,
 				81E95C141D62639600336598 /* ASTextNodeSnapshotTests.m in Sources */,
 				3C9C128519E616EF00E942A0 /* ASTableViewTests.mm in Sources */,
 				AEEC47E41C21D3D200EC1693 /* ASVideoNodeTests.m in Sources */,
 				254C6B521BF8FE6D003EC431 /* ASTextKitTruncationTests.mm in Sources */,
 				058D0A3D195D057000B7D73C /* ASTextKitCoreTextAdditionsTests.m in Sources */,
 				CC3B20901C3F892D00798563 /* ASBridgedPropertiesTests.mm in Sources */,
+				CCE4F9BE1F0ECE5200062E4E /* ASTLayoutFixture.mm in Sources */,
 				058D0A40195D057000B7D73C /* ASTextNodeTests.m in Sources */,
 				DBC453221C5FD97200B16017 /* ASDisplayNodeImplicitHierarchyTests.m in Sources */,
 				058D0A41195D057000B7D73C /* ASTextNodeWordKernerTests.mm in Sources */,

CHANGELOG.md

@@ -14,6 +14,7 @@
 - [Layout] Fix an issue that causes a pending layout to be applied multiple times.  [Huy Nguyen](https://github.com/nguyenhuy) [#695](https://github.com/TextureGroup/Texture/pull/695)
 - [ASScrollNode] Ensure the node respects the given size range while calculating its layout. [#637](https://github.com/TextureGroup/Texture/pull/637) [Huy Nguyen](https://github.com/nguyenhuy)
 - [ASScrollNode] Invalidate the node's calculated layout if its scrollable directions changed. Also add unit tests for the class. [#637](https://github.com/TextureGroup/Texture/pull/637) [Huy Nguyen](https://github.com/nguyenhuy)
+- Add new unit testing to the layout engine. [Adlai Holler](https://github.com/Adlai-Holler) [#424](https://github.com/TextureGroup/Texture/pull/424)
 
 ## 2.6
 - [Xcode 9] Updated to require Xcode 9 (to fix warnings) [Garrett Moon](https://github.com/garrettmoon)

Source/ASDisplayNode+Layout.mm

@@ -85,6 +85,7 @@ - (ASLayout *)layoutThatFits:(ASSizeRange)constrainedSize parentSize:(CGSize)par
     layout = [self calculateLayoutThatFits:constrainedSize
                           restrictedToSize:self.style.size
                       relativeToParentSize:parentSize];
+    as_log_verbose(ASLayoutLog(), "Established pending layout for %@ in %s", self, sel_getName(_cmd));
     _pendingDisplayNodeLayout = std::make_shared<ASDisplayNodeLayout>(layout, constrainedSize, parentSize, version);
     ASDisplayNodeAssertNotNil(layout, @"-[ASDisplayNode layoutThatFits:parentSize:] newly calculated layout should not be nil! %@", self);
   }

Source/ASDisplayNode.mm

@@ -2762,7 +2762,8 @@ - (void)setHierarchyState:(ASHierarchyState)newState
     }
   }
 
-  ASDisplayNodeLogEvent(self, @"setHierarchyState: oldState = %@, newState = %@", NSStringFromASHierarchyState(oldState), NSStringFromASHierarchyState(newState));
+  ASDisplayNodeLogEvent(self, @"setHierarchyState: %@", NSStringFromASHierarchyStateChange(oldState, newState));
+  as_log_verbose(ASNodeLog(), "%s%@ %@", sel_getName(_cmd), NSStringFromASHierarchyStateChange(oldState, newState), self);
 }
 
 - (void)willEnterHierarchy

Source/Details/_ASDisplayLayer.mm

@@ -25,6 +25,7 @@
 #import <AsyncDisplayKit/ASDisplayNodeInternal.h>
 #import <AsyncDisplayKit/ASDisplayNode+FrameworkPrivate.h>
 #import <AsyncDisplayKit/ASObjectDescriptionHelpers.h>
+#import <AsyncDisplayKit/ASLog.h>
 
 @implementation _ASDisplayLayer
 {
@@ -93,6 +94,7 @@ - (void)setContents:(id)contents
 - (void)setNeedsLayout
 {
   ASDisplayNodeAssertMainThread();
+  as_log_verbose(ASNodeLog(), "%s on %@", sel_getName(_cmd), self);
   [super setNeedsLayout];
 }
 #endif

Source/Layout/ASLayout.mm

@@ -23,6 +23,7 @@
 #import <AsyncDisplayKit/ASLayoutSpecUtilities.h>
 #import <AsyncDisplayKit/ASLayoutSpec+Subclasses.h>
 
+#import <AsyncDisplayKit/ASEqualityHelpers.h>
 #import <AsyncDisplayKit/ASInternalHelpers.h>
 #import <AsyncDisplayKit/ASObjectDescriptionHelpers.h>
 #import <AsyncDisplayKit/ASRectTable.h>
@@ -281,11 +282,12 @@ - (BOOL)isEqual:(id)object
   }
 
   if (!CGSizeEqualToSize(_size, layout.size)) return NO;
-  if (!CGPointEqualToPoint(_position, layout.position)) return NO;
+
+  if (!((ASPointIsNull(self.position) && ASPointIsNull(layout.position))
+        || CGPointEqualToPoint(self.position, layout.position))) return NO;
   if (_layoutElement != layout.layoutElement) return NO;
 
-  NSArray *sublayouts = layout.sublayouts;
-  if (sublayouts != _sublayouts && (sublayouts == nil || _sublayouts == nil || ![_sublayouts isEqual:sublayouts])) {
+  if (!ASObjectIsEqual(_sublayouts, layout.sublayouts)) {
     return NO;
   }
 

Source/Private/ASDisplayNode+FrameworkPrivate.h

@@ -99,6 +99,29 @@ __unused static NSString * _Nonnull NSStringFromASHierarchyState(ASHierarchyStat
 	return [NSString stringWithFormat:@"{ %@ }", [states componentsJoinedByString:@" | "]];
 }
 
+#define HIERARCHY_STATE_DELTA(Name) ({ \
+  if ((oldState & ASHierarchyState##Name) != (newState & ASHierarchyState##Name)) { \
+    [changes appendFormat:@"%c%s ", (newState & ASHierarchyState##Name ? '+' : '-'), #Name]; \
+  } \
+})
+
+__unused static NSString * _Nonnull NSStringFromASHierarchyStateChange(ASHierarchyState oldState, ASHierarchyState newState)
+{
+  if (oldState == newState) {
+    return @"{ }";
+  }
+
+  NSMutableString *changes = [NSMutableString stringWithString:@"{ "];
+  HIERARCHY_STATE_DELTA(Rasterized);
+  HIERARCHY_STATE_DELTA(RangeManaged);
+  HIERARCHY_STATE_DELTA(TransitioningSupernodes);
+  HIERARCHY_STATE_DELTA(LayoutPending);
+  [changes appendString:@"}"];
+  return changes;
+}
+
+#undef HIERARCHY_STATE_DELTA
+
 @interface ASDisplayNode () <ASDescriptionProvider, ASDebugDescriptionProvider>
 {
 @protected