basic unit tests

AsyncDisplayKitTests/ASDisplayNodeTests.m

@@ -71,6 +71,9 @@ for (ASDisplayNode *n in @[ nodes ]) {\
 @property (atomic, copy) CGSize(^calculateSizeBlock)(ASTestDisplayNode *node, CGSize size);
 @end
 
+@interface ASTestResponderNode : ASTestDisplayNode
+@end
+
 @implementation ASTestDisplayNode
 
 - (CGSize)calculateSizeThatFits:(CGSize)constrainedSize
@@ -91,9 +94,57 @@ for (ASDisplayNode *n in @[ nodes ]) {\
 @interface UIDisplayNodeTestView : UIView
 @end
 
+@interface UIResponderNodeTestView : _ASDisplayView
+@property(nonatomic) BOOL isFirstResponder;
+@end
+
 @implementation UIDisplayNodeTestView
 @end
 
+@interface ASTestWindow : UIWindow
+@end
+
+@implementation ASTestWindow
+
+- (id)firstResponder {
+  return self.subviews.firstObject;
+}
+
+@end
+
+@implementation ASTestResponderNode
+
++ (Class)viewClass {
+  return [UIResponderNodeTestView class];
+}
+
+- (BOOL)canBecomeFirstResponder {
+  return YES;
+}
+
+@end
+
+@implementation UIResponderNodeTestView
+
+- (BOOL)becomeFirstResponder {
+  self.isFirstResponder = YES;
+  return YES;
+}
+
+- (BOOL)canResignFirstResponder {
+  return YES;
+}
+
+- (BOOL)resignFirstResponder {
+  if (self.isFirstResponder) {
+    self.isFirstResponder = NO;
+    return YES;
+  }
+  return NO;
+}
+
+@end
+
 @interface ASDisplayNodeTests : XCTestCase
 @end
 
@@ -102,6 +153,25 @@ for (ASDisplayNode *n in @[ nodes ]) {\
   dispatch_queue_t queue;
 }
 
+- (void)testOverriddenFirstResponderBehavior {
+  ASTestDisplayNode *node = [[ASTestResponderNode alloc] init];
+  XCTAssertTrue([node canBecomeFirstResponder]);
+  XCTAssertTrue([node becomeFirstResponder]);
+}
+
+- (void)testDefaultFirstResponderBehavior {
+  ASTestDisplayNode *node = [[ASTestDisplayNode alloc] init];
+  XCTAssertFalse([node canBecomeFirstResponder]);
+  XCTAssertFalse([node becomeFirstResponder]);
+}
+
+- (void)testLayerBackedFirstResponderBehavior {
+  ASTestDisplayNode *node = [[ASTestResponderNode alloc] init];
+  node.layerBacked = YES;
+  XCTAssertTrue([node canBecomeFirstResponder]);
+  XCTAssertFalse([node becomeFirstResponder]);
+}
+
 - (void)setUp
 {
   [super setUp];