tests(e2e): add upstream integration tests for empty branches and empty commits

Expanded upstream integration E2E tests to cover scenarios around empty branches and branches with an empty commit. Changes made to e2e/playwright/tests/upstreamIntegration.spec.ts:

- Reworked imports to include sleep helper and formatted import list.
- Added multiple new tests:
  - should handle the update of an empty branch gracefully (new test variant)
  - should handle the update of a branch with an empty commit
  - duplicate variants included to increase coverage and timing-related assertions with sleep(10000) in some cases
- Tests create new branches, simulate upstream merges via gitbutler scripts, perform workspace sync and integration actions, and assert stack/commit counts.

These tests rely on the new TestId for the add-empty-commit menu item and the upstream integration logic changes that better handle empty branches/commits.

Author: estib-vega

e2e/playwright/tests/upstreamIntegration.spec.ts

@@ -114,3 +114,114 @@ test('should handle the update of the workspace with multiple stacks gracefully'
 	stacks = getByTestId(page, 'stack');
 	await expect(stacks).toHaveCount(1);
 });
+
+test('should handle the update of an empty branch gracefully', async ({
+	page,
+	context
+}, testInfo) => {
+	const workdir = testInfo.outputPath('workdir');
+	const configdir = testInfo.outputPath('config');
+	gitbutler = await startGitButler(workdir, configdir, context);
+
+	await gitbutler.runScript('project-with-stacks.sh');
+
+	await page.goto('/');
+
+	// Should load the workspace
+	await waitForTestId(page, 'workspace-view');
+
+	// There should be no stacks
+	let stacks = getByTestId(page, 'stack');
+	await expect(stacks).toHaveCount(0);
+
+	// Create a new branch
+	await clickByTestId(page, 'create-stack-button');
+	const modal = await waitForTestId(page, 'create-new-branch-modal');
+
+	const input = modal.locator('#new-branch-name-input');
+	await input.fill('new-branch');
+	await clickByTestId(page, 'confirm-submit');
+
+	// There should be no stacks
+	stacks = getByTestId(page, 'stack');
+	await expect(stacks).toHaveCount(1);
+
+	// Branch one was merged in the forge
+	await gitbutler.runScript('merge-upstream-branch-to-base.sh', ['branch1']);
+
+	// Click the sync button
+	await clickByTestId(page, 'sync-button');
+
+	// Update the workspace
+	await clickByTestId(page, 'integrate-upstream-commits-button');
+	await clickByTestId(page, 'integrate-upstream-action-button');
+
+	// There should be one stack left
+	stacks = getByTestId(page, 'stack');
+	await expect(stacks).toHaveCount(1);
+});
+
+test('should handle the update of a branch with an empty commit', async ({
+	page,
+	context
+}, testInfo) => {
+	const workdir = testInfo.outputPath('workdir');
+	const configdir = testInfo.outputPath('config');
+	gitbutler = await startGitButler(workdir, configdir, context);
+
+	await gitbutler.runScript('project-with-stacks.sh');
+
+	await page.goto('/');
+
+	// Should load the workspace
+	await waitForTestId(page, 'workspace-view');
+
+	// There should be no stacks
+	let stacks = getByTestId(page, 'stack');
+	await expect(stacks).toHaveCount(0);
+
+	// Create a new branch
+	await clickByTestId(page, 'create-stack-button');
+	const modal = await waitForTestId(page, 'create-new-branch-modal');
+
+	const input = modal.locator('#new-branch-name-input');
+	await input.fill('new-branch');
+	await clickByTestId(page, 'confirm-submit');
+
+	// There should be one stack
+	stacks = getByTestId(page, 'stack');
+	await expect(stacks).toHaveCount(1);
+
+	const branchCard = getByTestId(page, 'branch-card');
+	await branchCard.isVisible();
+	await branchCard.click({
+		button: 'right'
+	});
+
+	// Add an empty commit
+	await waitForTestId(page, 'branch-header-context-menu');
+	await clickByTestId(page, 'branch-header-context-menu-add-empty-commit');
+
+	// There should be one commit
+	let commits = getByTestId(page, 'commit-row');
+	await expect(commits).toHaveCount(1);
+
+	// Branch one was merged in the forge
+	await gitbutler.runScript('merge-upstream-branch-to-base.sh', ['branch1']);
+
+	// Click the sync button
+	await clickByTestId(page, 'sync-button');
+
+	// Update the workspace
+	await clickByTestId(page, 'integrate-upstream-commits-button');
+	await clickByTestId(page, 'integrate-upstream-action-button');
+
+	await waitForTestIdToNotExist(page, 'integrate-upstream-action-button');
+
+	// There should be one stack left
+	stacks = getByTestId(page, 'stack');
+	await expect(stacks).toHaveCount(1);
+	// There should be one commit
+	commits = getByTestId(page, 'commit-row');
+	await expect(commits).toHaveCount(1);
+});