Added fix to update text on navigation using up/down arrow (#4626)

* Added fix to update text on navigation using up/down arrow

* Fix incorrect alignment with ghost text

* Added tests

src/modules/launcher/PowerLauncher/MainWindow.xaml.cs

@@ -110,22 +110,31 @@ private void SuggestionsList_PreviewMouseLeftButtonUp(object sender, MouseButton
 
         private void ViewModel_PropertyChanged(object sender, PropertyChangedEventArgs e)
         {
-            if (Visibility == System.Windows.Visibility.Visible)
+            if(e.PropertyName == nameof(MainViewModel.MainWindowVisibility)) 
             {
-                // Not called on first launch
-                // Additionally called when deactivated by clicking on screen  
-                UpdatePosition();
-                BringProcessToForeground();
-
-                if (!_viewModel.LastQuerySelected)
+                if (Visibility == System.Windows.Visibility.Visible)
                 {
-                    _viewModel.LastQuerySelected = true;
+                    // Not called on first launch
+                    // Additionally called when deactivated by clicking on screen  
+                    UpdatePosition();
+                    BringProcessToForeground();
+
+                    if (!_viewModel.LastQuerySelected)
+                    {
+                        _viewModel.LastQuerySelected = true;
+                    }
                 }
-            }
+            }          
             else if (e.PropertyName == nameof(MainViewModel.SystemQueryText))
             {
                 this._isTextSetProgrammatically = true;
-                SearchBox.QueryTextBox.Text = _viewModel.SystemQueryText;
+                if (_viewModel.Results != null)
+                {
+                    SearchBox.QueryTextBox.Text = MainViewModel.GetSearchText(
+                        _viewModel.Results.SelectedIndex,
+                        _viewModel.SystemQueryText,
+                        _viewModel.QueryText);
+                }
             }
         }
 
@@ -261,32 +270,20 @@ private void SuggestionsList_SelectionChanged(object sender, SelectionChangedEve
             }
 
             // To populate the AutoCompleteTextBox as soon as the selection is changed or set.
-            // Setting it here instead of when the text is changed as there is a delay in executing the query and populating the result
-            SearchBox.AutoCompleteTextBlock.Text = ListView_FirstItem(_viewModel.QueryText);
+            // Setting it here instead of when the text is changed as there is a delay in executing the query and populating the result        
+            if (_viewModel.Results != null)
+            {
+                SearchBox.AutoCompleteTextBlock.Text = MainViewModel.GetAutoCompleteText(
+                    _viewModel.Results.SelectedIndex,
+                    _viewModel.Results.SelectedItem?.ToString(),
+                    _viewModel.QueryText);
+            }          
         }
 
         private const int millisecondsToWait = 100;
         private static DateTime s_lastTimeOfTyping;
         private bool disposedValue = false;
 
-        private string ListView_FirstItem(String input)
-        {
-            if (!string.IsNullOrEmpty(input))
-            {
-                string selectedItem = _viewModel.Results?.SelectedItem?.ToString();
-                int selectedIndex = _viewModel.Results.SelectedIndex;
-                if (selectedItem != null && selectedIndex == 0)
-                {
-                    if (selectedItem.IndexOf(input, StringComparison.InvariantCultureIgnoreCase) == 0)
-                    {
-                        // Use the same case as the input query for the matched portion of the string
-                        return input + selectedItem.Substring(input.Length);
-                    }
-                }
-            }
-
-            return string.Empty;
-        }
         private void QueryTextBox_TextChanged(object sender, TextChangedEventArgs e)
         {          
             if (_isTextSetProgrammatically)

src/modules/launcher/Wox.Test/MainViewModelTest.cs

@@ -0,0 +1,211 @@
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Wox.Plugin;
+using Wox.ViewModel;
+
+namespace Wox.Test
+{
+    [TestFixture]
+    class MainViewModelTest
+    {
+        [Test]
+        public void MainViewModel_GetAutoCompleteTextReturnsEmptyString_WhenInputIsNull()
+        {
+            // Arrange
+            int index = 0;
+            string input = null;
+            String query = "M";
+
+            // Act
+            string autoCompleteText = MainViewModel.GetAutoCompleteText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, string.Empty);
+        }
+
+        [Test]
+        public void MainViewModel_GetAutoCompleteTextReturnsEmptyString_WhenInputIsEmpty()
+        {
+            // Arrange
+            int index = 0;
+            string input = string.Empty;
+            String query = "M";
+
+            // Act
+            string autoCompleteText = MainViewModel.GetAutoCompleteText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, string.Empty);
+        }
+
+        [Test]
+        public void MainViewModel_GetAutoCompleteTextReturnsEmptyString_WhenQueryIsNull()
+        {
+            // Arrange
+            int index = 0;
+            string input = "M";
+            String query = null;
+
+            // Act
+            string autoCompleteText = MainViewModel.GetAutoCompleteText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, string.Empty);
+        }
+
+        [Test]
+        public void MainViewModel_GetAutoCompleteTextReturnsEmptyString_WhenQueryIsEmpty()
+        {
+            // Arrange
+            int index = 0;
+            string input = "M";
+            String query = string.Empty;
+
+            // Act
+            string autoCompleteText = MainViewModel.GetAutoCompleteText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, string.Empty);
+        }
+
+        [Test]
+        public void MainViewModel_GetAutoCompleteTextReturnsEmptyString_WhenIndexIsNonZero()
+        {
+            // Arrange
+            int index = 2;
+            string input = "Visual";
+            String query = "Vis";
+
+            // Act
+            string autoCompleteText = MainViewModel.GetAutoCompleteText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, string.Empty);
+        }
+
+        [Test]
+        public void MainViewModel_GetAutoCompleteTextReturnsMatchingString_WhenIndexIsZeroAndMatch()
+        {
+            // Arrange
+            int index = 0;
+            string input = "VISUAL";
+            String query = "VIs";
+            string ExpectedAutoCompleteText = "VIsUAL";
+
+            // Act
+            string autoCompleteText = MainViewModel.GetAutoCompleteText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, ExpectedAutoCompleteText);
+        }
+
+        [Test]
+        public void MainViewModel_GetAutoCompleteTextReturnsEmptyString_WhenIndexIsZeroAndNoMatch()
+        {
+            // Arrange
+            int index = 0;
+            string input = "VISUAL";
+            String query = "Vim";
+            string ExpectedAutoCompleteText = string.Empty;
+
+            // Act
+            string autoCompleteText = MainViewModel.GetAutoCompleteText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, ExpectedAutoCompleteText);
+        }
+
+        [Test]
+        public void MainViewModel_GetSearchTextReturnsEmptyString_WhenInputIsNull()
+        {
+            // Arrange
+            int index = 0;
+            string input = null;
+            String query = "M";
+
+            // Act
+            string autoCompleteText = MainViewModel.GetSearchText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, string.Empty);
+        }
+
+        [Test]
+        public void MainViewModel_GetSearchTextReturnsEmptyString_WhenInputIsEmpty()
+        {
+            // Arrange
+            int index = 0;
+            string input = string.Empty;
+            String query = "M";
+
+            // Act
+            string autoCompleteText = MainViewModel.GetSearchText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, string.Empty);
+        }
+
+        [Test]
+        public void MainViewModel_GetSearchTextReturnsInputString_WhenQueryIsNull()
+        {
+            // Arrange
+            int index = 0;
+            string input = "Visual";
+            String query = null;
+
+            // Act
+            string autoCompleteText = MainViewModel.GetSearchText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, input);
+        }
+
+        [Test]
+        public void MainViewModel_GetSearchTextReturnsInputString_WhenQueryIsEmpty()
+        {
+            // Arrange
+            int index = 0;
+            string input = "Visual";
+            String query = string.Empty;
+
+            // Act
+            string autoCompleteText = MainViewModel.GetSearchText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, input);
+        }
+
+        [Test]
+        public void MainViewModel_GetSearchTextReturnsMatchingStringWithCase_WhenIndexIsZeroAndMatch()
+        {
+            // Arrange
+            int index = 0;
+            string input = "VISUAL";
+            String query = "VIs";
+            string ExpectedAutoCompleteText = "VIsUAL";
+
+            // Act
+            string autoCompleteText = MainViewModel.GetSearchText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, ExpectedAutoCompleteText);
+        }
+
+        [Test]
+        public void MainViewModel_GetSearchTextReturnsInput_WhenIndexIsZeroAndNoMatch()
+        {
+            // Arrange
+            int index = 0;
+            string input = "VISUAL";
+            String query = "Vim";
+
+            // Act
+            string autoCompleteText = MainViewModel.GetSearchText(index, input, query);
+
+            // Assert
+            Assert.AreEqual(autoCompleteText, input);
+        }
+    }
+}

src/modules/launcher/Wox/ViewModel/MainViewModel.cs

@@ -709,6 +709,40 @@ public void HandleContextMenu(Key AcceleratorKey, ModifierKeys AcceleratorModifi
             }
         }
 
+        public static string GetAutoCompleteText(int index, string input, String query)
+        {
+            if (!string.IsNullOrEmpty(input) && !string.IsNullOrEmpty(query))
+            {
+                if (index == 0)
+                {
+                    if (input.IndexOf(query, StringComparison.InvariantCultureIgnoreCase) == 0)
+                    {
+                        // Use the same case as the input query for the matched portion of the string
+                        return query + input.Substring(query.Length);
+                    }
+                }
+            }
+
+            return string.Empty;
+        }
+
+        public static string GetSearchText(int index, String input, string query)
+        {
+            if (!string.IsNullOrEmpty(input))
+            {
+                if (index == 0 && !string.IsNullOrEmpty(query))
+                {
+                    if (input.IndexOf(query, StringComparison.InvariantCultureIgnoreCase) == 0)
+                    {
+                        return query + input.Substring(query.Length);
+                    }
+                }
+                return input;
+            }
+
+            return string.Empty;
+        }
+
         protected virtual void Dispose(bool disposing)
         {
             if (!_disposed)