Add Test to make sure associated objects live/die with lifetime of UIView.

Summary: Wrote some tests to make sure the associated objects we use for layout live and die with the objects. This was worthwhile because it made me realize UIView+CSSLayout wasn't enabled to ARC. As a result, my tests were failing because they weren't explicitly deallocing nodes.

Reviewed By: rnystrom

Differential Revision: D4023324

fbshipit-source-id: 5356cf4f0522582d75f83b5eb2193d9bc8d63aee

uikit/CSSLayout/BUCK

@@ -7,8 +7,11 @@
 
 include_defs('//CSSLAYOUT_DEFS')
 
+UIKIT_CSSLAYOUT_COMPILER_FLAGS = ['-fobjc-arc']
+
 apple_library(
   name = 'CSSLayout',
+  compiler_flags = UIKIT_CSSLAYOUT_COMPILER_FLAGS,
   tests = [':CSSLayoutTests'],
   srcs = glob(['*.m']),
   exported_headers = glob(['*.h']),
@@ -24,6 +27,7 @@ apple_library(
 
 apple_test(
   name = 'CSSLayoutTests',
+  compiler_flags = UIKIT_CSSLAYOUT_COMPILER_FLAGS,
   info_plist = 'Tests/Info.plist',
   srcs = glob(['Tests/**/*.m']),
   frameworks = [

uikit/CSSLayout/Tests/CSSLayoutTests.m

@@ -16,6 +16,36 @@
 
 @implementation CSSLayoutTests
 
+- (void)testNodesAreDeallocedWithSingleView
+{
+  XCTAssertEqual(0, CSSNodeGetInstanceCount());
+
+  UIView *view = [[UIView alloc] initWithFrame:CGRectZero];
+  [view css_setFlex:1];
+  XCTAssertEqual(1, CSSNodeGetInstanceCount());
+  view = nil;
+
+  XCTAssertEqual(0, CSSNodeGetInstanceCount());
+}
+
+- (void)testNodesAreDeallocedCascade
+{
+  XCTAssertEqual(0, CSSNodeGetInstanceCount());
+
+  UIView *view = [[UIView alloc] initWithFrame:CGRectZero];
+  [view css_setFlex:1];
+
+  for (int i=0; i<10; i++) {
+    UIView *subview = [[UIView alloc] initWithFrame:CGRectZero];
+    [subview css_setFlex:1];
+    [view addSubview:subview];
+  }
+  XCTAssertEqual(11, CSSNodeGetInstanceCount());
+  view = nil;
+
+  XCTAssertEqual(0, CSSNodeGetInstanceCount());
+}
+
 - (void)testHiddenViewsAreNotMeasured
 {
   const CGSize firstSize = CGSizeMake(100, 100);

uikit/CSSLayout/UIView+CSSLayout.m

@@ -30,7 +30,6 @@ static void _updateFrameRecursive(UIView *view);
 
 - (void)dealloc
 {
-  [super dealloc];
   CSSNodeFree(_cnode);
 }
 @end