Merge branch 'master' of https://github.com/facebook/yoga into improve-objc-swift

# Conflicts:
#	YogaKit/UIView+Yoga.h
#	YogaKit/UIView+Yoga.m

YogaKit/Tests/YogaKitTests.m

@@ -268,4 +268,79 @@
   }
 }
 
+- (void)testyg_isLeafFlag
+{
+  UIView *view = [[UIView alloc] initWithFrame:CGRectZero];
+  XCTAssertTrue(view.yg_isLeaf);
+
+  for (int i=0; i<10; i++) {
+    UIView *subview = [[UIView alloc] initWithFrame:CGRectZero];
+    [view addSubview:subview];
+  }
+  XCTAssertTrue(view.yg_isLeaf);
+
+  [view yg_setUsesYoga:YES];
+  [view yg_setWidth:50.0];
+  XCTAssertTrue(view.yg_isLeaf);
+
+  UIView *const subview = view.subviews[0];
+  [subview yg_setUsesYoga:YES];
+  [subview yg_setWidth:50.0];
+  XCTAssertFalse(view.yg_isLeaf);
+}
+
+- (void)testThatWeCorrectlyAttachNestedViews
+{
+    UIView *container = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 300, 50)];
+    [container yg_setUsesYoga:YES];
+    [container yg_setFlexDirection:YGFlexDirectionColumn];
+
+    UIView *subview1 = [[UIView alloc] initWithFrame:CGRectZero];
+    [subview1 yg_setUsesYoga:YES];
+    [subview1 yg_setWidth:100];
+    [subview1 yg_setFlexGrow:1];
+    [subview1 yg_setFlexDirection:YGFlexDirectionColumn];
+    [container addSubview:subview1];
+
+    UIView *subview2 = [[UIView alloc] initWithFrame:CGRectZero];
+    [subview2 yg_setUsesYoga:YES];
+    [subview2 yg_setWidth:150];
+    [subview2 yg_setFlexGrow:1];
+    [subview2 yg_setFlexDirection:YGFlexDirectionColumn];
+    [container addSubview:subview2];
+
+    for (UIView *view in @[subview1, subview2]) {
+        UIView *someView = [[UIView alloc] initWithFrame:CGRectZero];
+        [someView yg_setUsesYoga:YES];
+        [someView yg_setFlexGrow:1];
+        [view addSubview:someView];
+    }
+    [container yg_applyLayout];
+
+    // Add the same amount of new views, reapply layout.
+    for (UIView *view in @[subview1, subview2]) {
+        UIView *someView = [[UIView alloc] initWithFrame:CGRectZero];
+        [someView yg_setUsesYoga:YES];
+        [someView yg_setFlexGrow:1];
+        [view addSubview:someView];
+    }
+    [container yg_applyLayout];
+
+    XCTAssertTrue(CGSizeEqualToSize(CGSizeMake(100, 25), subview1.bounds.size), @"Actual size is %@", NSStringFromCGSize(subview1.bounds.size));
+    for (UIView *subview in subview1.subviews) {
+        const CGSize subviewSize = subview.bounds.size;
+        XCTAssertFalse(CGSizeEqualToSize(CGSizeZero, subviewSize));
+        XCTAssertFalse(isnan(subviewSize.height));
+        XCTAssertFalse(isnan(subviewSize.width));
+    }
+
+    XCTAssertTrue(CGSizeEqualToSize(CGSizeMake(150, 25), subview2.bounds.size), @"Actual size is %@", NSStringFromCGSize(subview2.bounds.size));
+    for (UIView *subview in subview2.subviews) {
+        const CGSize subviewSize = subview.bounds.size;
+        XCTAssertFalse(CGSizeEqualToSize(CGSizeZero, subview.bounds.size));
+        XCTAssertFalse(isnan(subviewSize.height));
+        XCTAssertFalse(isnan(subviewSize.width));
+    }
+}
+
 @end