Fix synchronous state of node if +viewClass or +layerClass is overwritten #trivial (#776)

* Fix synchronous state of node if +viewClass is overwritten

* Also check for _layerClass overwrite for synchronous flag

* Update some code style

Source/ASDisplayNode.mm

@@ -253,6 +253,11 @@ static ASDisplayNodeMethodOverrides GetASDisplayNodeMethodOverrides(Class c)
   
   _viewClass = [self.class viewClass];
   _layerClass = [self.class layerClass];
+  BOOL isSynchronous = ![_viewClass isSubclassOfClass:[_ASDisplayView class]]
+                        || ![_layerClass isSubclassOfClass:[_ASDisplayLayer class]];
+  setFlag(Synchronous, isSynchronous);
+  
+
   _contentsScaleForDisplay = ASScreenScale();
   _drawingPriority = ASDefaultDrawingPriority;
   

Tests/ASDisplayNodeTests.mm

@@ -173,6 +173,28 @@ for (ASDisplayNode *n in @[ nodes ]) {\
 
 @end
 
+@interface ASSynchronousTestDisplayNodeViaViewClass : ASDisplayNode
+@end
+
+@implementation ASSynchronousTestDisplayNodeViaViewClass
+
++ (Class)viewClass {
+  return [UIView class];
+}
+
+@end
+
+@interface ASSynchronousTestDisplayNodeViaLayerClass : ASDisplayNode
+@end
+
+@implementation ASSynchronousTestDisplayNodeViaLayerClass
+
++ (Class)layerClass {
+  return [CALayer class];
+}
+
+@end
+
 @interface UIDisplayNodeTestView : UIView
 @end
 
@@ -2354,4 +2376,16 @@ static bool stringContainsPointer(NSString *description, id p) {
   XCTAssertEqual(ASScreenScale(), UIScreen.mainScreen.scale);
 }
 
+- (void)testThatIfViewClassIsOverwrittenItsSynchronous
+{
+  ASSynchronousTestDisplayNodeViaViewClass *node = [[ASSynchronousTestDisplayNodeViaViewClass alloc] init];
+  XCTAssertTrue([node isSynchronous], @"Node should be synchronous if viewClass is ovewritten and not a subclass of _ASDisplayView");
+}
+
+- (void)testThatIfLayerClassIsOverwrittenItsSynchronous
+{
+  ASSynchronousTestDisplayNodeViaLayerClass *node = [[ASSynchronousTestDisplayNodeViaLayerClass alloc] init];
+  XCTAssertTrue([node isSynchronous], @"Node should be synchronous if viewClass is ovewritten and not a subclass of _ASDisplayView");
+}
+
 @end