[layoutng] Create correct constraint spaces for children

third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm_test.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/ng/ng_block_layout_algorithm.h"
 
 #include "core/layout/ng/ng_box.h"
 #include "core/layout/ng/ng_constraint_space.h"
 #include "core/layout/ng/ng_physical_fragment.h"
 #include "core/layout/ng/ng_length_utils.h"
@@ skipping 384 matching lines @@
 
   ASSERT_TRUE(child->Type() == NGPhysicalFragmentBase::FragmentBox);
   ASSERT_EQ(static_cast<const NGPhysicalFragment*>(child)->Children().size(),
             1UL);
 
   // div2
   child = static_cast<const NGPhysicalFragment*>(child)->Children()[0];
   EXPECT_EQ(kBorderTop + kPaddingTop, child->TopOffset());
   EXPECT_EQ(kBorderLeft + kPaddingLeft, child->LeftOffset());
 }
+
+TEST_F(NGBlockLayoutAlgorithmTest, PercentageSize) {
+  const int kPaddingLeft = 10;
+  const int kWidth = 30;
+  style_->setWidth(Length(kWidth, Fixed));
+  style_->setPaddingLeft(Length(kPaddingLeft, Fixed));
+
+  RefPtr<ComputedStyle> first_style = ComputedStyle::create();
+  first_style->setWidth(Length(40, Percent));
+  NGBox* first_child = new NGBox(first_style.get());
+
+  auto* space =
+      new NGConstraintSpace(HorizontalTopBottom, LeftToRight,
+                            NGLogicalSize(LayoutUnit(100), NGSizeIndefinite));
+  NGPhysicalFragment* frag = RunBlockLayoutAlgorithm(space, first_child);
+
+  EXPECT_EQ(frag->Width(), LayoutUnit(kWidth + kPaddingLeft));
+  EXPECT_EQ(frag->Type(), NGPhysicalFragmentBase::FragmentBox);
+  ASSERT_EQ(frag->Children().size(), 1UL);
+
+  const NGPhysicalFragmentBase* child = frag->Children()[0];
+  EXPECT_EQ(child->Width(), LayoutUnit(12));

[eae, 2016/09/20 08:09:38]

You might want an EXPECT_EQ(frag->Children().size(), 1) before trying to access
the first one. More helpful error than a out of bound crash.

[cbiesinger, 2016/09/20 13:43:37]

There's already an ASSERT_EQ for that above.

+}
 }  // namespace
 }  // namespace blink