MacViews/a11y: Allow accessibility clients to update the selected text.

ui/views/widget/native_widget_mac_accessibility_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.
 
 #include <memory>
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 318 matching lines @@
 
   // Test a read-only textfield.
   textfield->SetReadOnly(true);
   EXPECT_FALSE(
       [ax_node accessibilityIsAttributeSettable:NSAccessibilityValueAttribute]);
   [ax_node accessibilitySetValue:kTestStringValue
                     forAttribute:NSAccessibilityValueAttribute];
   EXPECT_NSEQ(kTestPlaceholderText,
               AttributeValueAtMidpoint(NSAccessibilityValueAttribute));
   EXPECT_EQ(base::SysNSStringToUTF16(kTestPlaceholderText), textfield->text());
+  textfield->SetReadOnly(false);
+
+  // Change the selection text when there is no selected text.
+  textfield->SelectRange(gfx::Range(0, 0));
+  EXPECT_TRUE([ax_node
+      accessibilityIsAttributeSettable:NSAccessibilitySelectedTextAttribute]);
+
+  NSString* new_string =
+      [kTestStringValue stringByAppendingString:kTestPlaceholderText];
+  [ax_node accessibilitySetValue:kTestStringValue
+                    forAttribute:NSAccessibilitySelectedTextAttribute];
+  EXPECT_NSEQ(new_string,
+              AttributeValueAtMidpoint(NSAccessibilityValueAttribute));
+  EXPECT_EQ(base::SysNSStringToUTF16(new_string), textfield->text());
+
+  // Replace entire selection.
+  gfx::Range test_range(0, [new_string length]);
+  textfield->SelectRange(test_range);
+  [ax_node accessibilitySetValue:kTestStringValue
+                    forAttribute:NSAccessibilitySelectedTextAttribute];
+  EXPECT_NSEQ(kTestStringValue,
+              AttributeValueAtMidpoint(NSAccessibilityValueAttribute));
+  EXPECT_EQ(base::SysNSStringToUTF16(kTestStringValue), textfield->text());
+
+  // Replace a section only.

[dmazzoni, 2016/10/26 04:26:02]

It'd be nice to try replacing something in the middle and check the selection
range after the call

[Patti Lor, 2016/10/27 00:38:48]

Done.

+  test_range = gfx::Range(5, [kTestStringValue length]);
+  new_string = [[kTestStringValue substringWithRange:NSMakeRange(0, 5)]
+      stringByAppendingString:kTestPlaceholderText];
+  textfield->SelectRange(test_range);
+  [ax_node accessibilitySetValue:kTestPlaceholderText
+                    forAttribute:NSAccessibilitySelectedTextAttribute];
+  EXPECT_NSEQ(new_string,
+              AttributeValueAtMidpoint(NSAccessibilityValueAttribute));
+  EXPECT_EQ(base::SysNSStringToUTF16(new_string), textfield->text());
 }
 
 }  // namespace views