Fixed a typo and added a test case

Summary: Fixed a typo of flexshrink and added a test case

Reviewed By: emilsjolander

Differential Revision: D7289221

fbshipit-source-id: 48ee9ccfac4adee51d515a366b5a11790f7236fc

tests/YGStyleTest.cpp

@@ -57,3 +57,26 @@ TEST(YogaTest, copy_style_modified_same) {
   YGNodeFree(node0);
   YGNodeFree(node1);
 }
+
+TEST(YogaTest, initialise_flexShrink_flexGrow) {
+  const YGNodeRef node0 = YGNodeNew();
+  YGNodeStyleSetFlexShrink(node0, 1);
+  ASSERT_EQ(1, YGNodeStyleGetFlexShrink(node0));
+
+  YGNodeStyleSetFlexShrink(node0, YGUndefined);
+  YGNodeStyleSetFlexGrow(node0, 3);
+  ASSERT_EQ(
+      0,
+      YGNodeStyleGetFlexShrink(
+          node0)); // Default value is Zero, if flex shrink is not defined
+  ASSERT_EQ(3, YGNodeStyleGetFlexGrow(node0));
+
+  YGNodeStyleSetFlexGrow(node0, YGUndefined);
+  YGNodeStyleSetFlexShrink(node0, 3);
+  ASSERT_EQ(
+      0,
+      YGNodeStyleGetFlexGrow(
+          node0)); // Default value is Zero, if flex grow is not defined
+  ASSERT_EQ(3, YGNodeStyleGetFlexShrink(node0));
+  YGNodeFree(node0);
+}

yoga/Yoga.cpp

@@ -778,7 +778,7 @@ void YGNodeStyleSetFlexShrink(const YGNodeRef node, const float flexShrink) {
   if (!YGFloatOptionalFloatEquals(node->getStyle().flexShrink, flexShrink)) {
     YGStyle style = node->getStyle();
     if (YGFloatIsUndefined(flexShrink)) {
-      style.flexGrow = {true, 0};
+      style.flexShrink = {true, 0};
     } else {
       style.flexShrink = {false, flexShrink};
     }