Put cursor at end of field if textfield is focused (#17367)

packages/flutter/lib/src/widgets/editable_text.dart

@@ -620,6 +620,9 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
     if (!_hasFocus) {
       // Clear the selection and composition state if this widget lost focus.
       _value = new TextEditingValue(text: _value.text);
+    } else if (!_value.selection.isValid) {
+      // Place cursor at the end if the selection is invalid when we receive focus.
+      widget.controller.selection = new TextSelection.collapsed(offset: _value.text.length);
     }
     updateKeepAlive();
   }

packages/flutter/test/widgets/editable_text_test.dart

@@ -783,6 +783,31 @@ void main() {
     expect(render.text.style.fontStyle, FontStyle.italic);
   });
 
+  testWidgets('autofocus sets cursor to the end of text', (WidgetTester tester) async {
+    const String text = 'hello world';
+    final FocusScopeNode focusScopeNode = new FocusScopeNode();
+    final FocusNode focusNode = new FocusNode();
+
+    controller.text = text;
+    await tester.pumpWidget(new Directionality(
+      textDirection: TextDirection.ltr,
+      child: new FocusScope(
+        node: focusScopeNode,
+        autofocus: true,
+        child: new EditableText(
+          controller: controller,
+          focusNode: focusNode,
+          autofocus: true,
+          style: textStyle,
+          cursorColor: cursorColor,
+        ),
+      ),
+    ));
+
+    expect(focusNode.hasFocus, true);
+    expect(controller.selection.isCollapsed, true);
+    expect(controller.selection.baseOffset, text.length);
+  });
 }
 
 class MockTextSelectionControls extends Mock implements TextSelectionControls {}