Add tests for measure caching

Summary: Measure caching is a crucial optimization to css-layout which re-uses the output of the measure function if possible. This logic was never covered by tests.

Reviewed By: lucasr

Differential Revision: D3790915

fbshipit-source-id: 7fe6d5ebb1303d3186d24d15e401901bc7c8ecdb

tests/CSSLayoutMeasureCacheTest.cpp

@@ -0,0 +1,81 @@
+/**
+ * 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-internal.h>
+#include <CSSLayoutTestUtils/CSSLayoutTestUtils.h>
+#include <gtest/gtest.h>
+
+static CSSSize _measure(void *context,
+                        float width,
+                        CSSMeasureMode widthMode,
+                        float height,
+                        CSSMeasureMode heightMode) {
+  int *measureCount = (int *)context;
+  *measureCount = *measureCount + 1;
+  return CSSSize {
+      .width = widthMode == CSSMeasureModeUndefined ? 10 : width,
+      .height = heightMode == CSSMeasureModeUndefined ? 10 : width,
+  };
+}
+
+TEST(CSSLayoutTest, measure_once_single_flexible_child) {
+  const CSSNodeRef root = CSSNodeNew();
+  CSSNodeStyleSetFlexDirection(root, CSSFlexDirectionRow);
+  CSSNodeStyleSetAlignItems(root, CSSAlignFlexStart);
+  CSSNodeStyleSetWidth(root, 100);
+  CSSNodeStyleSetHeight(root, 100);
+
+  const CSSNodeRef root_child0 = CSSNodeNew();
+  CSSNodeStyleSetWidth(root_child0, 50);
+  CSSNodeInsertChild(root, root_child0, 0);
+
+  const CSSNodeRef root_child1 = CSSNodeNew();
+  int measureCount = 0;
+  CSSNodeSetContext(root_child1, &measureCount);
+  CSSNodeSetMeasureFunc(root_child1, _measure);
+  CSSNodeStyleSetFlexGrow(root_child1, 1);
+  CSSNodeInsertChild(root, root_child1, 1);
+
+  const CSSNodeRef root_child2 = CSSNodeNew();
+  CSSNodeStyleSetWidth(root_child2, 50);
+  CSSNodeInsertChild(root, root_child2, 2);
+
+  CSSNodeCalculateLayout(root, CSSUndefined, CSSUndefined, CSSDirectionLTR);
+
+  ASSERT_EQ(1, measureCount);
+}
+
+TEST(CSSLayoutTest, dont_remeasure_text_node_height_change) {
+  const CSSNodeRef root = CSSNodeNew();
+  CSSNodeStyleSetAlignItems(root, CSSAlignFlexStart);
+  CSSNodeStyleSetWidth(root, 100);
+  CSSNodeStyleSetHeight(root, 100);
+
+  const CSSNodeRef root_child0 = CSSNodeNew();
+  CSSNodeStyleSetWidth(root_child0, 50);
+  CSSNodeStyleSetHeight(root_child0, 20);
+  CSSNodeInsertChild(root, root_child0, 0);
+
+  const CSSNodeRef root_child1 = CSSNodeNew();
+  int measureCount = 0;
+  CSSNodeSetContext(root_child1, &measureCount);
+  CSSNodeSetMeasureFunc(root_child1, _measure);
+  CSSNodeSetIsTextnode(root_child1, true);
+  CSSNodeStyleSetFlexGrow(root_child1, 1);
+  CSSNodeInsertChild(root, root_child1, 1);
+
+  const CSSNodeRef root_child2 = CSSNodeNew();
+  CSSNodeStyleSetWidth(root_child2, 50);
+  CSSNodeStyleSetHeight(root_child2, 20);
+  CSSNodeInsertChild(root, root_child2, 2);
+
+  CSSNodeCalculateLayout(root, CSSUndefined, CSSUndefined, CSSDirectionLTR);
+
+  ASSERT_EQ(1, measureCount);
+}