Handle fallback content case in FlatTreeTraversal::traverseSiblings()

third_party/WebKit/Source/core/dom/shadow/FlatTreeTraversalTest.cpp

Index: third_party/WebKit/Source/core/dom/shadow/FlatTreeTraversalTest.cpp
diff --git a/third_party/WebKit/Source/core/dom/shadow/FlatTreeTraversalTest.cpp b/third_party/WebKit/Source/core/dom/shadow/FlatTreeTraversalTest.cpp
index d87fd3ab2ca8daa0b9876d5726c12888e17987fb..0512a65300ca88b1fae518ccc4967db913861484 100644
--- a/third_party/WebKit/Source/core/dom/shadow/FlatTreeTraversalTest.cpp
+++ b/third_party/WebKit/Source/core/dom/shadow/FlatTreeTraversalTest.cpp
@@ -594,4 +594,35 @@ TEST_F(FlatTreeTraversalTest, v1SlotInDocumentTree) {
   EXPECT_EQ(parent, FlatTreeTraversal::parent(*slot));
 }
 
+TEST_F(FlatTreeTraversalTest, v1FallbackContent) {

[hayato, 2017/03/16 09:32:56]

Could you add a test for a slot which has both child nodes (which are not used
as fallback) and assigned nodes?

[kochi, 2017/03/16 10:09:54]

Added that case, and one more all-fallback contents case
(traversal from fallback content to fallback content).

+  const char* mainHTML = "<div id='d1'></div>";
+  const char* shadowHTML =
+      "<div id='before'></div>"
+      "<slot><p>fallback content</p></slot>"
+      "<div id='after'></div>";
+
+  setupDocumentTree(mainHTML);
+
+  Element* body = document().body();
+  Element* d1 = body->querySelector("#d1");
+
+  attachOpenShadowRoot(*d1, shadowHTML);
+  ShadowRoot* shadowRoot = d1->openShadowRoot();
+  Element* before = shadowRoot->querySelector("#before");
+  Element* after = shadowRoot->querySelector("#after");
+  Element* fallbackContent = shadowRoot->querySelector("p");
+
+  EXPECT_EQ(before, FlatTreeTraversal::firstChild(*d1));
+  EXPECT_EQ(after, FlatTreeTraversal::lastChild(*d1));
+  EXPECT_EQ(d1, FlatTreeTraversal::parent(*fallbackContent));
+
+  EXPECT_EQ(fallbackContent, FlatTreeTraversal::nextSibling(*before));
+  EXPECT_EQ(after, FlatTreeTraversal::nextSibling(*fallbackContent));
+  EXPECT_EQ(nullptr, FlatTreeTraversal::nextSibling(*after));
+
+  EXPECT_EQ(fallbackContent, FlatTreeTraversal::previousSibling(*after));
+  EXPECT_EQ(before, FlatTreeTraversal::previousSibling(*fallbackContent));
+  EXPECT_EQ(nullptr, FlatTreeTraversal::previousSibling(*before));
+}
+
 }  // namespace blink