[ios] EarlGrey test for scroll position restoration.

ios/web/shell/test/web_shell_page_state_egtest.mm

Index: ios/web/shell/test/web_shell_page_state_egtest.mm
diff --git a/ios/web/shell/test/web_shell_page_state_egtest.mm b/ios/web/shell/test/web_shell_page_state_egtest.mm
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+++ b/ios/web/shell/test/web_shell_page_state_egtest.mm
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+// 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 <CoreGraphics/CoreGraphics.h>
+#import <EarlGrey/EarlGrey.h>
+#import <Foundation/Foundation.h>
+#import <XCTest/XCTest.h>
+
+#import "ios/web/public/test/http_server.h"
+#include "ios/web/public/test/http_server_util.h"
+#include "ios/web/shell/test/app/navigation_test_util.h"
+#import "ios/web/shell/test/earl_grey/shell_matchers.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+namespace {
+
+// URLs for test pages.
+const char kLongPage1[] =
+    "http://ios/web/shell/test/http_server_files/tall_page.html";
+const char kLongPage2[] =
+    "http://ios/web/shell/test/http_server_files/tall_page.html?2";
+
+// Test scroll offsets.
+const CGFloat kScrollOffset1 = 20.0f;
+const CGFloat kScrollOffset2 = 40.0f;
+
+// Returns a matcher for asserting that element's content offset matches the
+// given |offset|.
+id<GREYMatcher> contentOffset(CGPoint offset) {
+  MatchesBlock matches = ^BOOL(UIScrollView* element) {
+    return CGPointEqualToPoint([element contentOffset], offset);
+  };
+  DescribeToBlock describe = ^(id<GREYDescription> description) {
+    [description appendText:@"contentOffset"];
+  };
+  return grey_allOf(
+      grey_kindOfClass([UIScrollView class]),
+      [[GREYElementMatcherBlock alloc] initWithMatchesBlock:matches
+                                           descriptionBlock:describe],
+      nil);
+}
+
+}  // namespace
+
+using web::shell_test_util::LoadUrl;
+using web::test::HttpServer;
+using web::webViewContainingText;
+
+// Page state test cases for the web shell.
+@interface CRWWebShellPageStateTest : XCTestCase
+@end
+
+@implementation CRWWebShellPageStateTest
+
+// Set up called once for the class.
++ (void)setUp {
+  [super setUp];
+  [[EarlGrey selectElementWithMatcher:webViewContainingText("Chromium")]
+      assertWithMatcher:grey_notNil()];
+  HttpServer::GetSharedInstance().StartOrDie();
+}
+
+// Tear down called once for the class.
++ (void)tearDown {
+  [super tearDown];
+  HttpServer::GetSharedInstance().Stop();
+}
+
+// Tear down called after each test.
+- (void)tearDown {
+  [super tearDown];
+  HttpServer::GetSharedInstance().RemoveAllResponseProviders();
+}
+
+// Tests that page scroll position of a page is restored upon returning to the
+// page via the back/forward buttons.
+- (void)testScrollPositionRestoring {
+  web::test::SetUpFileBasedHttpServer();
+
+  // Load first URL which is a long page.
+  LoadUrl(HttpServer::MakeUrl(kLongPage1));
+  // TODO(crbug.com/629116): Remove this once |LoadUrl| waits for the load
+  // completion.
+  [[EarlGrey selectElementWithMatcher:webViewContainingText("List of numbers")]
+      assertWithMatcher:grey_notNil()];
+
+  // Scroll the first page and verify the offset.
+  [[EarlGrey selectElementWithMatcher:web::webViewScrollView()]
+      performAction:grey_scrollInDirection(kGREYDirectionDown, kScrollOffset1)];
+  [[EarlGrey selectElementWithMatcher:web::webViewScrollView()]
+      assertWithMatcher:contentOffset(CGPointMake(0, kScrollOffset1))];
+
+  // Load second URL, which is also a long page.
+  GURL URL2 = HttpServer::MakeUrl(kLongPage2);
+  LoadUrl(URL2);
+  // TODO(crbug.com/629116): Remove these once |LoadUrl| waits for the load
+  // completion.
+  [[EarlGrey selectElementWithMatcher:web::addressFieldText(URL2.spec())]
+      assertWithMatcher:grey_notNil()];
+  [[EarlGrey selectElementWithMatcher:webViewContainingText("List of numbers")]
+      assertWithMatcher:grey_notNil()];
+
+  // Scroll the second page and verify the offset.
+  [[EarlGrey selectElementWithMatcher:web::webViewScrollView()]
+      performAction:grey_scrollInDirection(kGREYDirectionDown, kScrollOffset2)];
+  [[EarlGrey selectElementWithMatcher:web::webViewScrollView()]
+      assertWithMatcher:contentOffset(CGPointMake(0, kScrollOffset2))];
+
+  // Go back and verify that the first page offset has been restored.
+  [[EarlGrey selectElementWithMatcher:web::backButton()]
+      performAction:grey_tap()];
+  [[EarlGrey selectElementWithMatcher:web::webViewScrollView()]
+      assertWithMatcher:contentOffset(CGPointMake(0, kScrollOffset1))];
+
+  // Go forward and verify that the second page offset has been restored.
+  [[EarlGrey selectElementWithMatcher:web::forwardButton()]
+      performAction:grey_tap()];
+  [[EarlGrey selectElementWithMatcher:web::webViewScrollView()]
+      assertWithMatcher:contentOffset(CGPointMake(0, kScrollOffset2))];
+}
+
+@end