Web shell test to go back and forward.

ios/web/shell/test/utils/web_view_egutil.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/shell/test/utils/web_view_egutil.h"
+
+#import <WebKit/WebKit.h>
+
+#include "base/mac/bind_objc_block.h"
+#include "base/strings/utf_string_conversions.h"
+#import "base/test/ios/wait_util.h"
+#include "base/values.h"
+#import "ios/web/shell/view_controller.h"
+#include "ios/web/shell/test/utils/navigation_egutil.h"
+#include "ios/web/web_state/web_state_impl.h"
+
+namespace {
+
+// Constant for UI wait loop in seconds.
+const NSTimeInterval kSpinDelaySeconds = 0.01;
+
+// Constant for timeout in seconds while waiting for web element.
+const NSTimeInterval kWaitForWebElementTimeout = 4.0;
+
+// Script that returns document.body as a string.
+std::string kGetDocumentBodyJavaScript =
+    "document.body ? document.body.textContent : null";
+}
+
+@implementation GREYMatchers (WebShellAdditions)
+
++ (id<GREYMatcher>)matcherForWebViewContainingText:(NSString*)text {
+  MatchesBlock matches = ^BOOL(UIView* view) {
+    if (![view isKindOfClass:[WKWebView class]]) {
+      return NO;
+    }
+
+    ViewController* viewController =
+        (ViewController*)[[[[UIApplication sharedApplication] delegate] window]
+            rootViewController];
+    DCHECK(viewController);
+    web::WebState* webState = [viewController webState];
+    DCHECK(webState);
+
+    __block BOOL didSucceed = NO;
+    void (^searchForTextBlock)(const base::Value* value) =
+        ^(const base::Value* value) {
+          std::string response;
+          if (value && value->IsType(base::Value::TYPE_STRING)) {
+            value->GetAsString(&response);
+            if (response.find([text UTF8String]) == std::string::npos) {
+            } else {
+              didSucceed = YES;
+            }
+          }
+        };
+    NSDate* deadline =
+        [NSDate dateWithTimeIntervalSinceNow:kWaitForWebElementTimeout];
+    while (!([[NSDate date] compare:deadline] == NSOrderedDescending) &&
+           !didSucceed) {
+      webState->ExecuteJavaScript(base::UTF8ToUTF16(kGetDocumentBodyJavaScript),
+                                  base::BindBlock(searchForTextBlock));
+      base::test::ios::SpinRunLoopWithMaxDelay(
+          base::TimeDelta::FromSecondsD(kSpinDelaySeconds));
+    }
+    return didSucceed;
+  };
+
+  DescribeToBlock describe = ^void(id<GREYDescription> description) {
+    [description
+        appendText:[NSString stringWithFormat:@"web view containing %@", text]];
+  };
+
+  return [[[GREYElementMatcherBlock alloc] initWithMatchesBlock:matches
+                                               descriptionBlock:describe]
+      autorelease];
+}
+
+@end
+
+#if !(GREY_DISABLE_SHORTHAND)
+
+id<GREYMatcher> shell_webViewContainingText(NSString* text) {
+  return [GREYMatchers matcherForWebViewContainingText:text];
+}
+
+#endif