Replaces constructor with method to initialize dependencies, as not a…

…ll methods use them

Related dotnet#10773

## Proposed changes

- Adds code coverage to `FormatStringEditor`

## Customer Impact

- None

## Regression?

- No

## Risk

- Minimal

## Test methodology

- Unit tests

## Test environment(s)

- 9.0.100-rc.1.24452.12

src/System.Windows.Forms.Design/tests/UnitTests/System/Windows/Forms/Design/FormatStringEditorTests.cs

@@ -14,13 +14,13 @@ namespace System.Windows.Forms.Design.Tests;
 public class FormatStringEditorTests
 {
  private readonly FormatStringEditor _editor = new();
- private readonly Mock<IWindowsFormsEditorService> _mockEditorService;
- private readonly Mock<IComponentChangeService> _mockChangeService;
- private readonly Mock<IServiceProvider> _provider;
- private readonly Mock<ITypeDescriptorContext> _context;
- private readonly DataGridViewCellStyle _cellStyle;
+ private Mock<IWindowsFormsEditorService>? _mockEditorService;
+ private Mock<IComponentChangeService>? _mockChangeService;
+ private Mock<IServiceProvider>? _provider;
+ private Mock<ITypeDescriptorContext>? _context;
+ private DataGridViewCellStyle? _cellStyle;
 
- public FormatStringEditorTests()
+ public void ArrangeDependencies()
  {
  _mockEditorService = new();
  _mockChangeService = new();
@@ -45,62 +45,68 @@ public void EditValue_InvalidProvider_ReturnsValue(IServiceProvider provider, ob
  [CommonMemberData(typeof(CommonTestHelperEx), nameof(CommonTestHelperEx.GetITypeDescriptorContextTestData))]
  public void GetEditStyle_Invoke_ReturnsModal(ITypeDescriptorContext context)
  {
-  _editor.GetEditStyle(context).Should().Be(UITypeEditorEditStyle.Modal);
+ _editor.GetEditStyle(context).Should().Be(UITypeEditorEditStyle.Modal);
  }
 
  [WinFormsFact]
  public void EditValue_ShowsDialogAndUpdatesValue()
  {
- object? result = _editor.EditValue(_context.Object, _provider.Object, "NewValue");
+ ArrangeDependencies();
+
+ object? result = _editor.EditValue(_context?.Object, _provider!.Object, "NewValue");
 
  result.Should().Be("NewValue");
- _mockEditorService.Verify(es => es.ShowDialog(It.IsAny<FormatStringDialog>()), Times.Once);
+ _mockEditorService?.Verify(es => es.ShowDialog(It.IsAny<FormatStringDialog>()), Times.Once);
  }
 
  [WinFormsFact]
  public void EditValue_CallsOnComponentChanging_Once()
  {
- _editor.EditValue(_context.Object, _provider.Object, "NewValue");
+ ArrangeDependencies();
+
+ _editor.EditValue(_context?.Object, _provider!.Object, "NewValue");
 
- _mockChangeService.Verify(
- cs => cs.OnComponentChanging(_cellStyle, TypeDescriptor.GetProperties(_cellStyle)["Format"]),
+ _mockChangeService?.Verify(
+ cs => cs.OnComponentChanging(_cellStyle!, TypeDescriptor.GetProperties(_cellStyle!)["Format"]),
  Times.Once);
 
- _mockChangeService.Verify(
- cs => cs.OnComponentChanging(_cellStyle, TypeDescriptor.GetProperties(_cellStyle)["NullValue"]),
+ _mockChangeService?.Verify(
+ cs => cs.OnComponentChanging(_cellStyle!, TypeDescriptor.GetProperties(_cellStyle!)["NullValue"]),
  Times.Once);
 
- _mockChangeService.Verify(
- cs => cs.OnComponentChanging(_cellStyle, TypeDescriptor.GetProperties(_cellStyle)["FormatProvider"]),
+ _mockChangeService?.Verify(
+ cs => cs.OnComponentChanging(_cellStyle!, TypeDescriptor.GetProperties(_cellStyle!)["FormatProvider"]),
  Times.Once);
  }
 
  [WinFormsFact]
  public void EditValue_WithDirtyDialog_CallsOnComponentChanged_Once()
  {
+ ArrangeDependencies();
+
  dynamic? dialog = _editor.TestAccessor().Dynamic._formatStringDialog;
- dialog = new FormatStringDialog(_context.Object);
+ dialog = new FormatStringDialog(_context?.Object);
 
  var dialogField = typeof(FormatStringEditor).GetField("_formatStringDialog",
  Reflection.BindingFlags.NonPublic | Reflection.BindingFlags.Instance);
- dialogField?.SetValue(_editor, dialog); 
+ dialogField?.SetValue(_editor, dialog);
 
  var dirtyField = typeof(FormatStringDialog).GetField("_dirty",
  Reflection.BindingFlags.NonPublic | Reflection.BindingFlags.Instance);
  dirtyField?.SetValue(dialog, true);
 
- _editor.EditValue(_context.Object, _provider.Object, "NewValue");
+ _editor.EditValue(_context?.Object, _provider!.Object!, "NewValue");
 
- _mockChangeService.Verify(
- cs => cs.OnComponentChanged(_cellStyle, TypeDescriptor.GetProperties(_cellStyle)["Format"], null, null),
+ _mockChangeService?.Verify(
+ cs => cs.OnComponentChanged(_cellStyle!, TypeDescriptor.GetProperties(_cellStyle!)["Format"], null, null),
  Times.Once);
 
- _mockChangeService.Verify(
- cs => cs.OnComponentChanged(_cellStyle, TypeDescriptor.GetProperties(_cellStyle)["NullValue"], null, null),
+ _mockChangeService?.Verify(
+ cs => cs.OnComponentChanged(_cellStyle!, TypeDescriptor.GetProperties(_cellStyle!)["NullValue"], null, null),
  Times.Once);
 
- _mockChangeService.Verify(
- cs => cs.OnComponentChanged(_cellStyle, TypeDescriptor.GetProperties(_cellStyle)["FormatProvider"], null, null),
+ _mockChangeService?.Verify(
+ cs => cs.OnComponentChanged(_cellStyle!, TypeDescriptor.GetProperties(_cellStyle!)["FormatProvider"], null, null),
  Times.Once);
  }
 }