Add experiment support to gentest

Summary:
This diff does two things
- Clean up some of the generated code making the files smaller.
- Add experiment support to generated tests allowing us to use gentest for things still being experimented with such as more compliant flex-basis behavior.

Reviewed By: gkassabli

Differential Revision: D4226734

fbshipit-source-id: 2cc1471c21883e8e326f16e7a8bb1a3657acd84b

tests/CSSLayoutRoundingMeasureFuncTest.cpp

@@ -0,0 +1,73 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include <CSSLayout/CSSLayout.h>
+#include <gtest/gtest.h>
+
+static CSSSize _measureFloor(CSSNodeRef node,
+  float width,
+  CSSMeasureMode widthMode,
+  float height,
+  CSSMeasureMode heightMode) {
+
+  return CSSSize{
+    width = 10.2,
+    height = 10.2,
+  };
+}
+
+static CSSSize _measureCeil(CSSNodeRef node,
+  float width,
+  CSSMeasureMode widthMode,
+  float height,
+  CSSMeasureMode heightMode) {
+
+  return CSSSize{
+    width = 10.5,
+    height = 10.5,
+  };
+}
+
+TEST(CSSLayoutTest, rounding_feature_with_custom_measure_func_floor) {
+  CSSLayoutSetExperimentalFeatureEnabled(CSSExperimentalFeatureRounding, true);
+
+  const CSSNodeRef root = CSSNodeNew();
+
+  const CSSNodeRef root_child0 = CSSNodeNew();
+  CSSNodeSetMeasureFunc(root_child0, _measureFloor);
+  CSSNodeInsertChild(root, root_child0, 0);
+
+  CSSNodeCalculateLayout(root, CSSUndefined, CSSUndefined, CSSDirectionLTR);
+
+  ASSERT_FLOAT_EQ(10, CSSNodeLayoutGetWidth(root_child0));
+  ASSERT_FLOAT_EQ(10, CSSNodeLayoutGetHeight(root_child0));
+
+  CSSNodeFreeRecursive(root);
+
+  CSSLayoutSetExperimentalFeatureEnabled(CSSExperimentalFeatureRounding, false);
+}
+
+TEST(CSSLayoutTest, rounding_feature_with_custom_measure_func_ceil) {
+  CSSLayoutSetExperimentalFeatureEnabled(CSSExperimentalFeatureRounding, true);
+
+  const CSSNodeRef root = CSSNodeNew();
+
+  const CSSNodeRef root_child0 = CSSNodeNew();
+  CSSNodeSetMeasureFunc(root_child0, _measureCeil);
+  CSSNodeInsertChild(root, root_child0, 0);
+
+  CSSNodeCalculateLayout(root, CSSUndefined, CSSUndefined, CSSDirectionLTR);
+
+  ASSERT_FLOAT_EQ(11, CSSNodeLayoutGetWidth(root_child0));
+  ASSERT_FLOAT_EQ(11, CSSNodeLayoutGetHeight(root_child0));
+
+  CSSNodeFreeRecursive(root);
+
+  CSSLayoutSetExperimentalFeatureEnabled(CSSExperimentalFeatureRounding, false);
+}