refactor: improve test resilience and code readability

- Use expect.objectContaining in tests for better resilience to future option additions
- Extract showTextDocument options to named constant for improved readability
- Addresses Copilot review feedback on PR #5282

src/integrations/editor/DiffViewProvider.ts

@@ -503,8 +503,9 @@ export class DiffViewProvider {
 
 			// Pre-open the file as a text document to ensure it doesn't open in preview mode
 			// This fixes issues with files that have custom editor associations (like markdown preview)
+			const showOptions = { preview: false, viewColumn: vscode.ViewColumn.Active, preserveFocus: true }
 			vscode.window
-				.showTextDocument(uri, { preview: false, viewColumn: vscode.ViewColumn.Active, preserveFocus: true })
+				.showTextDocument(uri, showOptions)
 				.then(() => {
 					// Execute the diff command after ensuring the file is open as text
 					return vscode.commands.executeCommand(

src/integrations/editor/__tests__/DiffViewProvider.spec.ts

@@ -176,7 +176,13 @@ describe("DiffViewProvider", () => {
 			// Mock showTextDocument to track when it's called
 			vi.mocked(vscode.window.showTextDocument).mockImplementation(async (uri, options) => {
 				callOrder.push("showTextDocument")
-				expect(options).toEqual({ preview: false, viewColumn: vscode.ViewColumn.Active, preserveFocus: true })
+				expect(options).toEqual(
+					expect.objectContaining({
+						preview: false,
+						viewColumn: vscode.ViewColumn.Active,
+						preserveFocus: true,
+					}),
+				)
 				return mockEditor as any
 			})
 
@@ -211,7 +217,7 @@ describe("DiffViewProvider", () => {
 			// Verify that showTextDocument was called with preview: false
 			expect(vscode.window.showTextDocument).toHaveBeenCalledWith(
 				expect.objectContaining({ fsPath: `${mockCwd}/test.md` }),
-				{ preview: false, viewColumn: vscode.ViewColumn.Active, preserveFocus: true },
+				expect.objectContaining({ preview: false, viewColumn: vscode.ViewColumn.Active, preserveFocus: true }),
 			)
 
 			// Verify that the diff command was executed