[ios] Correctly determine last seen WKNavigation object.

ios/web/web_state/ui/crw_wk_navigation_states_unittest.mm

+// 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.
+
+#import "ios/web/web_state/ui/crw_wk_navigation_states.h"
+
+#import <WebKit/WebKit.h>
+
+#import "base/mac/scoped_nsobject.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "testing/platform_test.h"
+
+namespace web {
+
+// Test fixture for CRWWKNavigationStates testing.
+class CRWWKNavigationStatesTest : public PlatformTest {
+ protected:
+  CRWWKNavigationStatesTest()
+      : navigation1_(static_cast<WKNavigation*>([[NSObject alloc] init])),
+        navigation2_(static_cast<WKNavigation*>([[NSObject alloc] init])),
+        states_([[CRWWKNavigationStates alloc] init]) {}
+
+ protected:
+  base::scoped_nsobject<WKNavigation> navigation1_;
+  base::scoped_nsobject<WKNavigation> navigation2_;
+  base::scoped_nsobject<CRWWKNavigationStates> states_;
+};
+
+// Tests |lastAddedNavigation| method.
+TEST_F(CRWWKNavigationStatesTest, LastAddedNavigation) {
+  // navigation_1 is the only navigation and it is the latest.
+  [states_ setState:WKNavigationState::REQUESTED forNavigation:navigation1_];
+  EXPECT_EQ(navigation1_, [states_ lastAddedNavigation]);
+
+  // navigation_2 is added later and hence the latest.
+  [states_ setState:WKNavigationState::REQUESTED forNavigation:navigation2_];
+  EXPECT_EQ(navigation2_, [states_ lastAddedNavigation]);
+
+  // Updating state for existing navigation does not make it the latest.
+  [states_ setState:WKNavigationState::STARTED forNavigation:navigation1_];
+  EXPECT_EQ(navigation2_, [states_ lastAddedNavigation]);
+}
+
+// Tests |stateForNavigation:| method.
+TEST_F(CRWWKNavigationStatesTest, StateForNavigation) {
+  [states_ setState:WKNavigationState::REQUESTED forNavigation:navigation1_];
+  EXPECT_EQ(WKNavigationState::REQUESTED,
+            [states_ stateForNavigation:navigation1_]);
+
+  [states_ setState:WKNavigationState::REQUESTED forNavigation:navigation2_];
+  EXPECT_EQ(WKNavigationState::REQUESTED,
+            [states_ stateForNavigation:navigation2_]);
+
+  [states_ setState:WKNavigationState::STARTED forNavigation:navigation1_];
+  EXPECT_EQ(WKNavigationState::STARTED,
+            [states_ stateForNavigation:navigation1_]);
+}
+
+}  // namespace web