playwright: Wait for file stat nodes (#12310)

The `theia-workspace.test.ts` checks for existence of file nodes in the
explorer view to verify whether the workspace has been prepared
correctly. However, occasionally it may happen that the explorer view
doesn't show them yet, as the files are just being loaded.

This resulted in occasionally flaky test executions (#12063).

To fix this problem, we now use the `existsDirectoryNode` and
`existsFileNode` checks to explicitly wait for them to appear and
only fail if the check times out.

Contributed on behalf of STMicroelectronics.
Fixes #12063

Change-Id: I4226a7d6f657c6a1363160655da4c94cd0984379

examples/playwright/src/tests/theia-workspace.test.ts

@@ -33,19 +33,20 @@ test.describe('Theia Workspace', () => {
         const ws = new TheiaWorkspace(['src/tests/resources/sample-files1']);
         const app = await TheiaApp.load(page, ws);
         const explorer = await app.openView(TheiaExplorerView);
-        const fileStatElements = await explorer.visibleFileStatNodes(DOT_FILES_FILTER);
         // resources/sample-files1 contains one folder and one file
-        expect(fileStatElements.length).toBe(2);
+        expect(await explorer.existsDirectoryNode('sampleFolder')).toBe(true);
+        expect(await explorer.existsFileNode('sample.txt')).toBe(true);
     });
 
     test('should be initialized with the contents of multiple file locations', async () => {
         const ws = new TheiaWorkspace(['src/tests/resources/sample-files1', 'src/tests/resources/sample-files2']);
         const app = await TheiaApp.load(page, ws);
         const explorer = await app.openView(TheiaExplorerView);
-        const fileStatElements = await explorer.visibleFileStatNodes(DOT_FILES_FILTER);
         // resources/sample-files1 contains one folder and one file
+        expect(await explorer.existsDirectoryNode('sampleFolder')).toBe(true);
+        expect(await explorer.existsFileNode('sample.txt')).toBe(true);
         // resources/sample-files2 contains one file
-        expect(fileStatElements.length).toBe(3);
+        expect(await explorer.existsFileNode('another-sample.txt')).toBe(true);
     });
 
 });