[LayoutNG] Remove derived constraint spaces from opportunity iterator.

third_party/WebKit/Source/core/layout/ng/ng_constraint_space_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_constraint_space.h"
 
 #include "core/layout/ng/ng_constraint_space.h"
 #include "core/layout/ng/ng_layout_opportunity_iterator.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 27 matching lines @@
   EXPECT_TRUE(horz_space->FixedInlineSize());
   EXPECT_TRUE(vert_space->FixedBlockSize());
 
   EXPECT_FALSE(horz_space->FixedBlockSize());
   EXPECT_FALSE(vert_space->FixedInlineSize());
 
   EXPECT_EQ(FragmentColumn, horz_space->BlockFragmentationType());
   EXPECT_EQ(FragmentNone, vert_space->BlockFragmentationType());
 }
 
-static String OpportunityToString(const NGConstraintSpace* opportunity) {
-  return opportunity ? opportunity->ToString() : String("(null)");
+static String OpportunityToString(const NGLayoutOpportunity& opportunity) {
+  return opportunity.IsEmpty() ? String("(empty)") : opportunity.ToString();
 }
 
 TEST(NGConstraintSpaceTest, LayoutOpportunitiesNoExclusions) {
   NGPhysicalSize physical_size;
   physical_size.width = LayoutUnit(600);
   physical_size.height = LayoutUnit(400);
   auto* physical_space = new NGPhysicalConstraintSpace(physical_size);
   auto* space =
       new NGConstraintSpace(HorizontalTopBottom, LeftToRight, physical_space);
 
   bool for_inline_or_bfc = true;
   auto* iterator = space->LayoutOpportunities(NGClearNone, for_inline_or_bfc);
 
   EXPECT_EQ("0,0 600x400", OpportunityToString(iterator->Next()));
-  EXPECT_EQ("(null)", OpportunityToString(iterator->Next()));
+  EXPECT_EQ("(empty)", OpportunityToString(iterator->Next()));
 }
 
 TEST(NGConstraintSpaceTest, LayoutOpportunitiesTopRightExclusion) {
   NGPhysicalSize physical_size;
   physical_size.width = LayoutUnit(600);
   physical_size.height = LayoutUnit(400);
   auto* physical_space = new NGPhysicalConstraintSpace(physical_size);
 
   // Add a 100x100 exclusion in the top right corner.
   physical_space->AddExclusion(new NGExclusion(
       LayoutUnit(0), LayoutUnit(600), LayoutUnit(100), LayoutUnit(500)));
 
   auto* space =
       new NGConstraintSpace(HorizontalTopBottom, LeftToRight, physical_space);
   bool for_inline_or_bfc = true;
   auto* iterator = space->LayoutOpportunities(NGClearNone, for_inline_or_bfc);
 
   // First opportunity should be to the left of the exclusion.
   EXPECT_EQ("0,0 500x400", OpportunityToString(iterator->Next()));
 
   // Second opportunity should be below the exclusion.
   EXPECT_EQ("0,100 600x300", OpportunityToString(iterator->Next()));
 
   // There should be no third opportunity.
-  EXPECT_EQ("(null)", OpportunityToString(iterator->Next()));
+  EXPECT_EQ("(empty)", OpportunityToString(iterator->Next()));
 }
 
 TEST(NGConstraintSpaceTest, LayoutOpportunitiesTopLeftExclusion) {
   NGPhysicalSize physical_size;
   physical_size.width = LayoutUnit(600);
   physical_size.height = LayoutUnit(400);
   auto* physical_space = new NGPhysicalConstraintSpace(physical_size);
 
   // Add a 100x100 exclusion in the top left corner.
   physical_space->AddExclusion(new NGExclusion(LayoutUnit(0), LayoutUnit(100),
                                                LayoutUnit(100), LayoutUnit(0)));
 
   auto* space =
       new NGConstraintSpace(HorizontalTopBottom, LeftToRight, physical_space);
   bool for_inline_or_bfc = true;
   auto* iterator = space->LayoutOpportunities(NGClearNone, for_inline_or_bfc);
 
   // First opportunity should be to the right of the exclusion.
   EXPECT_EQ("100,0 500x400", OpportunityToString(iterator->Next()));
 
   // Second opportunity should be below the exclusion.
   EXPECT_EQ("0,100 600x300", OpportunityToString(iterator->Next()));
 
   // There should be no third opportunity.
-  EXPECT_EQ("(null)", OpportunityToString(iterator->Next()));
+  EXPECT_EQ("(empty)", OpportunityToString(iterator->Next()));
 }
 
 // Verifies that Layout Opportunity iterator produces 7 layout opportunities
 // from 4 start points created by 2 CSS exclusions positioned in the middle of
 // the main constraint space.
 //
 // Test case visual representation:
 //
 //         100  200  300  400  500
 //     (1)--|----|----|-(2)|----|-(3)+
@@ skipping 38 matching lines @@
   EXPECT_EQ("250,0 250x400", OpportunityToString(iterator->Next()));
 
   // 3rd Start point
   EXPECT_EQ("550,0 50x400", OpportunityToString(iterator->Next()));
 
   // 4th Start point
   EXPECT_EQ("0,300 600x50", OpportunityToString(iterator->Next()));
   EXPECT_EQ("0,300 500x100", OpportunityToString(iterator->Next()));
 
   // Iterator is exhausted.
-  EXPECT_EQ("(null)", OpportunityToString(iterator->Next()));
+  EXPECT_EQ("(empty)", OpportunityToString(iterator->Next()));
 }
 
 // Verifies that Layout Opportunity iterator ignores the exclusion that is not
 // within constraint space.
 //
 // Test case visual representation:
 //
 //         100  200  300  400  500
 //     +----|----|----|----|----|----+
 //  50 |                             |
@@ skipping 12 matching lines @@
   auto* physical_space = new NGPhysicalConstraintSpace(physical_size);
   physical_space->AddExclusion(new NGExclusion(LayoutUnit(150), LayoutUnit(100),
                                                LayoutUnit(200), LayoutUnit(0)));
   auto* space =
       new NGConstraintSpace(HorizontalTopBottom, LeftToRight, physical_space);
 
   bool for_inline_or_bfc = true;
   auto* iterator = space->LayoutOpportunities(NGClearNone, for_inline_or_bfc);
 
   EXPECT_EQ("0,0 600x100", OpportunityToString(iterator->Next()));
-  EXPECT_EQ("(null)", OpportunityToString(iterator->Next()));
+  EXPECT_EQ("(empty)", OpportunityToString(iterator->Next()));
 }
 
 }  // namespace
 }  // namespace blink