#7320 Fixing flaky ComboBox unit test (#7323)

src/System.Windows.Forms/tests/IntegrationTests/UIIntegrationTests/ComboBoxTests.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System.Text;
 using Xunit;
 using Xunit.Abstractions;
 
@@ -36,102 +35,5 @@ await RunSingleControlTestAsync<ComboBox>((form, comboBox) =>
  return Task.CompletedTask;
  });
  }
-
- [WinFormsFact]
- public async Task ComboBox_Select_Item_By_UpArrowKeyAsync()
- {
- int expectedKeyPressesCount = 9;
- await RunComboBoxTestAsync(async (form, comboBox) =>
- {
- StringBuilder stringBuilder = new();
-
- // Reset EventsCount because the control gets selected right after the creation.
- comboBox.ResetEventsCount();
- for (int i = 0; i < expectedKeyPressesCount; i++)
- {
- await Task.Delay(100);
- await InputSimulator.SendAsync(
- form,
- inputSimulator => inputSimulator.Keyboard
- .Sleep(100)
- .KeyPress(WindowsInput.Native.VirtualKeyCode.UP));
-
- await Task.Delay(100);
- stringBuilder.AppendLine($"i:{i + 1}, eventsCount:{comboBox.EventsCount}");
- }
-
- TestOutputHelper.WriteLine($"{stringBuilder}");
- Assert.Equal(expectedKeyPressesCount, comboBox.EventsCount);
- },
- expectedKeyPressesCount,
- selectedIndex: 9);
- }
-
- [WinFormsFact]
- public async Task ComboBox_Select_Item_By_DownArrowKeyAsync()
- {
- int expectedKeyPressesCount = 9;
- await RunComboBoxTestAsync(async (form, comboBox) =>
- {
- // Reset EventsCount because the control gets selected right after the creation.
- comboBox.ResetEventsCount();
- for (int i = 0; i < expectedKeyPressesCount; i++)
- {
- await InputSimulator.SendAsync(
- form,
- inputSimulator => inputSimulator.Keyboard.KeyPress(WindowsInput.Native.VirtualKeyCode.DOWN));
-
- Assert.Equal(i + 1, comboBox.EventsCount);
- }
-
- Assert.Equal(expectedKeyPressesCount, comboBox.EventsCount);
- },
- expectedKeyPressesCount,
- selectedIndex: 0);
- }
-
- private async Task RunComboBoxTestAsync(Func<Form, ComboBoxWithSelectCounter, Task> runTest, int numberOfItemsToAdd, int selectedIndex)
- {
- await RunSingleControlTestAsync(
- testDriverAsync: runTest,
- createControl: () =>
- {
- ComboBoxWithSelectCounter control = new();
- control.AddItems(numberOfItemsToAdd);
- control.SelectedIndex = selectedIndex;
- return control;
- },
- createForm: () =>
- {
- return new()
- {
- Size = new(500, 300),
- };
- });
- }
-
- private class ComboBoxWithSelectCounter : ComboBox
- {
- public int EventsCount { get; private set; }
-
- public void AddItems(int numToAdd)
- {
- for (int i = 0; i <= numToAdd; i++)
- {
- Items.Add($"Item {i}");
- }
- }
-
- protected override void OnSelectedIndexChanged(EventArgs e)
- {
- base.OnSelectedIndexChanged(e);
- EventsCount++;
- }
-
- public void ResetEventsCount()
- {
- EventsCount = 0;
- }
- }
  }
 }

src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/ComboBoxTests.cs

@@ -2271,6 +2271,31 @@ public void OwnerDrawComboBox_Verify_OnMeasureItem_Receives_Correct_Arguments()
  }
  }
 
+ [WinFormsTheory]
+ [InlineData(Keys.Up, 9, 9)]
+ [InlineData(Keys.Down, 9, 0)]
+ public void ComboBox_Select_Item_By_Key(Keys key, int expectedKeyPressesCount, int selectedIndex)
+ {
+ using ComboBoxWithSelectCounter comboBox = new();
+ comboBox.AddItems(expectedKeyPressesCount+1);
+ comboBox.CreateControl();
+ comboBox.SelectedIndex = selectedIndex;
+ comboBox.ResetEventsCount();
+
+ // https://docs.microsoft.com/windows/win32/inputdev/wm-keyup
+ // The MSDN page tells us what bits of lParam to use for each of the parameters.
+ // All we need to do is some bit shifting to assemble lParam.
+ nint keyCode = (nint)key;
+ nint lParam = 0x00000001 | keyCode << 16;
+ for (int i = 0; i < expectedKeyPressesCount; i++)
+ {
+ User32.SendMessageW(comboBox, User32.WM.KEYDOWN, keyCode, lParam);
+ User32.SendMessageW(comboBox, User32.WM.KEYUP, keyCode, lParam);
+ }
+
+ Assert.Equal(expectedKeyPressesCount, comboBox.EventsCount);
+ }
+
  private void InitializeItems(ComboBox comboBox, int numItems)
  {
  for (int i = 0; i < numItems; i++)
@@ -2472,6 +2497,15 @@ public void ConfigureForCtrlBackspace(int cursorRelativeToEnd = 0)
  private class ComboBoxWithSelectCounter : ComboBox
  {
  public int EventsCount { get; private set; }
+
+ public void AddItems(int numToAdd)
+ {
+ for (int i = 0; i < numToAdd; i++)
+ {
+ Items.Add($"Item {i}");
+ }
+ }
+
  protected override void OnSelectedIndexChanged(EventArgs e)
  {
  base.OnSelectedIndexChanged(e);