Add WebStateListOrderController to control WebState insertion.

ios/shared/chrome/browser/tabs/web_state_list_order_controller_unittest.mm

+// 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.
+
+#import "ios/shared/chrome/browser/tabs/web_state_list_order_controller.h"
+
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#import "ios/shared/chrome/browser/tabs/web_state_list.h"
+#import "ios/web/public/test/fakes/test_navigation_manager.h"
+#import "ios/web/public/test/fakes/test_web_state.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "testing/platform_test.h"
+#include "ui/base/page_transition_types.h"
+
+namespace {
+const char kURL[] = "https://chromium.org/";
+
+// A fake NavigationManager used to test opener-opened relationship in the
+// WebStateList.
+class FakeNavigationManer : public web::TestNavigationManager {
+ public:
+  FakeNavigationManer() = default;
+
+  // web::NavigationManager implementation.
+  int GetCurrentItemIndex() const override { return 0; }
+  int GetLastCommittedItemIndex() const override { return 0; }
+
+  DISALLOW_COPY_AND_ASSIGN(FakeNavigationManer);
+};
+
+}  // namespace
+
+class WebStateListOrderControllerTest : public PlatformTest {
+ public:
+  WebStateListOrderControllerTest()
+      : web_state_list_(WebStateList::WebStateOwned),
+        order_controller_(&web_state_list_) {}
+
+ protected:
+  WebStateList web_state_list_;
+  WebStateListOrderController order_controller_;
+
+  // This method should return std::unique_ptr<> however, due to the complex
+  // ownership of Tab, WebStateList currently uses raw pointers. Change this
+  // once Tab ownership is sane, see http://crbug.com/546222 for progress.
+  web::WebState* CreateWebState() {
+    auto test_web_state = base::MakeUnique<web::TestWebState>();
+    test_web_state->SetCurrentURL(GURL(kURL));
+    test_web_state->SetNavigationManager(
+        base::MakeUnique<FakeNavigationManer>());
+    return test_web_state.release();
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(WebStateListOrderControllerTest);
+};
+
+TEST_F(WebStateListOrderControllerTest, DetermineInsertionIndex) {
+  web_state_list_.InsertWebState(0, CreateWebState(), nullptr);
+  web_state_list_.InsertWebState(1, CreateWebState(), nullptr);
+  web::WebState* opener = web_state_list_.GetWebStateAt(0);
+
+  // Verify that first child WebState is inserted after |opener| if there are
+  // no other childs.

[rohitrao (ping after 24h), 2017/02/17 13:04:12]

children.

+  EXPECT_EQ(1, order_controller_.DetermineInsertionIndex(
+                   ui::PAGE_TRANSITION_LINK, opener));
+
+  // Verify that child WebState is inserted at the end if it is not a "LINK"
+  // transition.
+  EXPECT_EQ(2, order_controller_.DetermineInsertionIndex(
+                   ui::PAGE_TRANSITION_GENERATED, opener));
+
+  // Verify that  WebState is inserted at the end if it has no opener.
+  EXPECT_EQ(2, order_controller_.DetermineInsertionIndex(
+                   ui::PAGE_TRANSITION_LINK, nullptr));
+
+  // Add a child WebState to |opener|, and verify that a second child would be
+  // inserted after the first.
+  web_state_list_.InsertWebState(2, CreateWebState(), opener);
+
+  EXPECT_EQ(3, order_controller_.DetermineInsertionIndex(
+                   ui::PAGE_TRANSITION_LINK, opener));
+
+  // Add a grand-child to |opener|, and verify that adding another child to
+  // |opener| would be inserted before the grand-child.
+  web_state_list_.InsertWebState(3, CreateWebState(),
+                                 web_state_list_.GetWebStateAt(1));
+
+  EXPECT_EQ(3, order_controller_.DetermineInsertionIndex(
+                   ui::PAGE_TRANSITION_LINK, opener));
+}