Create merge conflict tests

Author: navn-r

.eslintignore

@@ -3,3 +3,4 @@ dist
 coverage
 **/*.d.ts
 tests
+ui-tests

ui-tests/tests/hello-world.spec.ts

@@ -0,0 +1,60 @@
+import { test, expect, Locator } from '@playwright/test';
+
+const TARGET_URL = process.env.TARGET_URL ?? 'http://localhost:8888';
+
+test.describe('Merge conflict tests', () => {
+  test.beforeEach(async ({ page }) => {
+    // URL for merge conflict example repository
+    await page.goto(`${TARGET_URL}/lab/tree/merge-conflict-example`);
+
+    await page.waitForSelector('#jupyterlab-splash', { state: 'detached' });
+    await page.waitForSelector('div[role="main"] >> text=Launcher');
+
+    const gitTabBar = await page.waitForSelector(
+      '.lm-TabBar-tab[data-id="jp-git-sessions"]'
+    );
+    const selected = await gitTabBar.getAttribute('aria-selected');
+
+    // Git panel may be already open on launch
+    if (selected === 'false') {
+      await gitTabBar.click();
+    }
+  });
+
+  test('should diff conflicted text file', async ({ page }) => {
+    await page.click('[title="file.txt • Conflicted"]', { clickCount: 2 });
+    await page.waitForSelector(
+      '.jp-git-diff-parent-widget[id^="CURRENT-INCOMING"] .jp-spinner',
+      { state: 'detached' }
+    );
+    await page.waitForSelector('.jp-git-diff-root');
+
+    // Verify 3-way merge view appears
+    const banner = page.locator('.jp-git-diff-banner');
+    await expect(banner).toHaveText(/CURRENT/);
+    await expect(banner).toHaveText(/RESULT/);
+    await expect(banner).toHaveText(/INCOMING/);
+
+    const mergeDiff = page.locator('.CodeMirror-merge-3pane');
+    await expect(mergeDiff).toBeVisible();
+  });
+
+  test('should diff conflicted notebook file', async ({ page }) => {
+    await page.click('[title="Untitled.ipynb • Conflicted"]', {
+      clickCount: 2
+    });
+    await page.waitForSelector(
+      '.jp-git-diff-parent-widget[id^="CURRENT-INCOMING"] .jp-spinner',
+      { state: 'detached' }
+    );
+    await page.waitForSelector('.jp-git-diff-root');
+
+    // Verify notebook merge view appears
+    const banner = page.locator('.jp-git-diff-banner');
+    await expect(banner).toHaveText(/CURRENT/);
+    await expect(banner).toHaveText(/INCOMING/);
+
+    const mergeDiff = page.locator('.jp-Notebook-merge');
+    await expect(mergeDiff).toBeVisible();
+  });
+});