[LayoutNG] Introduce block child iterator.

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

+// Copyright 2017 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_child_iterator.h"
+
+#include "core/layout/LayoutTestHelper.h"
+#include "core/layout/ng/ng_block_break_token.h"
+#include "core/layout/ng/ng_block_node.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace blink {
+namespace {
+
+class NGBlockChildIteratorTest : public RenderingTest {};
+
+TEST_F(NGBlockChildIteratorTest, testNullFirstChild) {

[Gleb Lanbin, 2017/02/22 20:52:10]

1) testNullFirstChild is a function name, so it should start with an uppercase
character.
2) prefix "test" is redundant here and below.

[ikilpatrick, 2017/02/22 22:25:22]

Done.

+  NGBlockChildIterator iterator(nullptr, nullptr);
+  EXPECT_EQ(NGBlockChildIterator::Entry(nullptr, nullptr),
+            iterator.NextChild());
+}
+
+TEST_F(NGBlockChildIteratorTest, testNoBreakToken) {
+  setBodyInnerHTML(R"HTML(
+      <div id='child1'></div>
+      <div id='child2'></div>
+      <div id='child3'></div>
+    )HTML");
+  NGLayoutInputNode* node1 =
+      new NGBlockNode(toLayoutBlockFlow(getLayoutObjectByElementId("child1")));
+  NGLayoutInputNode* node2 = node1->NextSibling();
+  NGLayoutInputNode* node3 = node2->NextSibling();
+
+  // The iterator should loop through three children.
+  NGBlockChildIterator iterator(node1, nullptr);
+  EXPECT_EQ(NGBlockChildIterator::Entry(node1, nullptr), iterator.NextChild());

[Gleb Lanbin, 2017/02/22 20:52:10]

.nit

s/EXPECT_EQ/ASSERT_EQ/g "Assert" will halt the execution of test while "expect"
will let it continue. I think in your case each iterator's return depends on the
previous one. It's better to use ASSERT_EQ here to avoid crashes in tests.

[ikilpatrick, 2017/02/22 22:25:22]

Done.

+  EXPECT_EQ(NGBlockChildIterator::Entry(node2, nullptr), iterator.NextChild());
+  EXPECT_EQ(NGBlockChildIterator::Entry(node3, nullptr), iterator.NextChild());
+  EXPECT_EQ(NGBlockChildIterator::Entry(nullptr, nullptr),
+            iterator.NextChild());
+}
+
+TEST_F(NGBlockChildIteratorTest, testBreakTokenWithFinishedChild) {
+  setBodyInnerHTML(R"HTML(
+      <div id='container'>
+        <div id='child1'></div>
+        <div id='child2'></div>
+        <div id='child3'></div>
+      </div>
+    )HTML");
+  NGBlockNode* container = new NGBlockNode(
+      toLayoutBlockFlow(getLayoutObjectByElementId("container")));
+  NGLayoutInputNode* node1 = container->FirstChild();
+  NGLayoutInputNode* node2 = node1->NextSibling();
+  NGLayoutInputNode* node3 = node2->NextSibling();
+
+  HeapVector<Member<NGBreakToken>> child_break_tokens;
+  child_break_tokens.push_back(new NGBlockBreakToken(toNGBlockNode(node1)));
+  NGBlockBreakToken* parent_token =
+      new NGBlockBreakToken(container, LayoutUnit(50), child_break_tokens);
+
+  // The iterator should loop through two children.
+  NGBlockChildIterator iterator(node1, parent_token);
+  EXPECT_EQ(NGBlockChildIterator::Entry(node2, nullptr), iterator.NextChild());
+  EXPECT_EQ(NGBlockChildIterator::Entry(node3, nullptr), iterator.NextChild());
+  EXPECT_EQ(NGBlockChildIterator::Entry(nullptr, nullptr),
+            iterator.NextChild());
+
+  child_break_tokens.push_back(new NGBlockBreakToken(toNGBlockNode(node2)));
+  parent_token =
+      new NGBlockBreakToken(container, LayoutUnit(50), child_break_tokens);
+
+  // The iterator should loop through two children.
+  NGBlockChildIterator iterator2(node1, parent_token);
+  EXPECT_EQ(NGBlockChildIterator::Entry(node1, nullptr), iterator2.NextChild());
+  EXPECT_EQ(NGBlockChildIterator::Entry(node3, nullptr), iterator2.NextChild());
+  EXPECT_EQ(NGBlockChildIterator::Entry(nullptr, nullptr),
+            iterator2.NextChild());
+}
+
+TEST_F(NGBlockChildIteratorTest, testBreakTokenWithUnFinishedChild) {
+  setBodyInnerHTML(R"HTML(
+      <div id='container'>
+        <div id='child1'></div>
+        <div id='child2'></div>
+        <div id='child3'></div>
+      </div>
+    )HTML");
+  NGBlockNode* container = new NGBlockNode(
+      toLayoutBlockFlow(getLayoutObjectByElementId("container")));
+  NGLayoutInputNode* node1 = container->FirstChild();
+  NGLayoutInputNode* node2 = node1->NextSibling();
+  NGLayoutInputNode* node3 = node2->NextSibling();
+
+  HeapVector<Member<NGBreakToken>> child_break_tokens;
+  NGBreakToken* child_token = new NGBlockBreakToken(
+      toNGBlockNode(node1), LayoutUnit(), child_break_tokens);
+  child_break_tokens.push_back(child_token);
+  NGBlockBreakToken* parent_token =
+      new NGBlockBreakToken(container, LayoutUnit(50), child_break_tokens);
+
+  // The iterator should loop through three children, one with a break token.
+  NGBlockChildIterator iterator(node1, parent_token);
+  EXPECT_EQ(NGBlockChildIterator::Entry(node1, child_token),
+            iterator.NextChild());
+  EXPECT_EQ(NGBlockChildIterator::Entry(node2, nullptr), iterator.NextChild());
+  EXPECT_EQ(NGBlockChildIterator::Entry(node3, nullptr), iterator.NextChild());
+  EXPECT_EQ(NGBlockChildIterator::Entry(nullptr, nullptr),
+            iterator.NextChild());
+
+  child_token = new NGBlockBreakToken(toNGBlockNode(node2), LayoutUnit(),
+                                      child_break_tokens);
+  child_break_tokens.push_back(child_token);
+  parent_token =
+      new NGBlockBreakToken(container, LayoutUnit(50), child_break_tokens);
+
+  // The iterator should loop through three children, one with a break token.
+  NGBlockChildIterator iterator2(node1, parent_token);
+  EXPECT_EQ(NGBlockChildIterator::Entry(node1, nullptr), iterator2.NextChild());
+  EXPECT_EQ(NGBlockChildIterator::Entry(node2, child_token),
+            iterator2.NextChild());
+  EXPECT_EQ(NGBlockChildIterator::Entry(node3, nullptr), iterator2.NextChild());
+  EXPECT_EQ(NGBlockChildIterator::Entry(nullptr, nullptr),
+            iterator2.NextChild());
+}
+
+}  // namespace
+}  // namespace blink