fix: rebuild project tree from scratch when listing tests

Instead of filtering tests assuming there are no two projects with same name
we always rebuild test tree from scratch and restore previos test results in
the list mode.

Fixes https://github.com/microsoft/playwright/issues/30396

packages/playwright/src/isomorphic/teleReceiver.ts

@@ -146,6 +146,11 @@ export class TeleReporterReceiver {
     this._reporter = reporter;
   }
 
+  reset() {
+    this._rootSuite._entries = [];
+    this._tests.clear();
+  }
+
   dispatch(message: JsonEvent): Promise<void> | void {
     const { method, params } = message;
     if (method === 'onConfigure') {
@@ -206,35 +211,6 @@ export class TeleReporterReceiver {
     projectSuite._project = this._parseProject(project);
     for (const suite of project.suites)
       this._mergeSuiteInto(suite, projectSuite);
-
-    // Remove deleted tests when listing. Empty suites will be auto-filtered
-    // in the UI layer.
-    if (this.isListing) {
-      const testIds = new Set<string>();
-      const collectIds = (suite: JsonSuite) => {
-        suite.entries.forEach(entry => {
-          if ('testId' in entry)
-            testIds.add(entry.testId);
-          else
-            collectIds(entry);
-        });
-      };
-      project.suites.forEach(collectIds);
-
-      const filterTests = (suite: TeleSuite) => {
-        suite._entries = suite._entries.filter(entry => {
-          if (entry.type === 'test') {
-            if (testIds.has(entry.id))
-              return true;
-            this._tests.delete(entry.id);
-            return false;
-          }
-          filterTests(entry);
-          return true;
-        });
-      };
-      filterTests(projectSuite);
-    }
   }
 
   private _onBegin() {
@@ -585,7 +561,7 @@ class TeleTestStep implements reporterTypes.TestStep {
   }
 }
 
-class TeleTestResult implements reporterTypes.TestResult {
+export class TeleTestResult implements reporterTypes.TestResult {
   retry: reporterTypes.TestResult['retry'];
   parallelIndex: reporterTypes.TestResult['parallelIndex'] = -1;
   workerIndex: reporterTypes.TestResult['workerIndex'] = -1;

packages/trace-viewer/src/ui/teleSuiteUpdater.ts

@@ -15,6 +15,7 @@
  */
 
 import { TeleReporterReceiver, TeleSuite } from '@testIsomorphic/teleReceiver';
+import type { TeleTestResult } from '@testIsomorphic/teleReceiver';
 import { statusEx } from '@testIsomorphic/testTree';
 import type { ReporterV2 } from 'playwright/src/reporters/reporterV2';
 import type * as reporterTypes from 'playwright/types/testReporter';
@@ -27,7 +28,7 @@ export type TeleSuiteUpdaterOptions = {
 };
 
 export class TeleSuiteUpdater {
-  rootSuite: reporterTypes.Suite | undefined;
+  rootSuite: TeleSuite | undefined;
   config: reporterTypes.FullConfig | undefined;
   readonly loadErrors: reporterTypes.TestError[] = [];
   readonly progress: Progress = {
@@ -76,7 +77,7 @@ export class TeleSuiteUpdater {
 
       onBegin: (suite: reporterTypes.Suite) => {
         if (!this.rootSuite)
-          this.rootSuite = suite;
+          this.rootSuite = suite as TeleSuite;
         this.progress.total = this._lastRunTestCount;
         this.progress.passed = 0;
         this.progress.failed = 0;
@@ -123,10 +124,13 @@ export class TeleSuiteUpdater {
   }
 
   processListReport(report: any[]) {
-    this._receiver.isListing = true;
+    // Save test results and reset all projects.
+    const results = this.rootSuite && TestResultsSnapshot.saveResults(this.rootSuite);
+    this._receiver.reset();
     for (const message of report)
       this._receiver.dispatch(message);
-    this._receiver.isListing = false;
+    // After recreating all projects restore previous results.
+    results?.restore(this.rootSuite!)
   }
 
   processTestReportEvent(message: any) {
@@ -145,3 +149,36 @@ export class TeleSuiteUpdater {
     };
   }
 }
+
+class TestResultsSnapshot {
+  private _testIdToResults = new Map<string, TeleTestResult[]>();
+
+  static saveResults(rootSuite: TeleSuite) {
+    const snapshot = new TestResultsSnapshot();
+    snapshot._saveForSuite(rootSuite);
+    return snapshot;
+  }
+
+  private _saveForSuite(suite: TeleSuite) {
+    for (const entry of suite.entries()) {
+      if (entry.type === 'test') {
+        if (entry.results.length)
+          this._testIdToResults.set(entry.id, entry.results);
+      } else {
+        this._saveForSuite(entry);
+      }
+    }
+  }
+
+  restore(suite: TeleSuite) {
+    for (const entry of suite.entries()) {
+      if (entry.type === 'test') {
+        const results = this._testIdToResults.get(entry.id);
+        if (results)
+          entry.results = results;
+      } else {
+        this.restore(entry);
+      }
+    }
+  }
+}

tests/playwright-test/ui-mode-test-tree.spec.ts

@@ -48,6 +48,60 @@ test('should list tests', async ({ runUITest }) => {
   `);
 });
 
+test('should list all tests from projects with clashing names', async ({ runUITest }) => {
+  test.info().annotations.push({ type: 'issue', description: 'https://github.com/microsoft/playwright/issues/30396' });
+  const { page } = await runUITest({
+    'playwright.config.ts': `
+      import { defineConfig } from '@playwright/test';
+
+      export default defineConfig({
+        projects: [
+          {
+            name: 'proj-uno',
+            testDir: './foo',
+          },
+          {
+            name: 'proj-dos',
+            testDir: './foo',
+          },
+          {
+            name: 'proj-uno',
+            testDir: './bar',
+          },
+          {
+            name: 'proj-dos',
+            testDir: './bar',
+          },
+        ]
+      });
+    `,
+    'foo/a.test.ts': `
+      import { test, expect } from '@playwright/test';
+      test('one', () => {});
+      test('two', () => {});
+    `,
+    'bar/b.test.ts': `
+      import { test, expect } from '@playwright/test';
+      test('three', () => {});
+      test('four', () => {});
+    `,
+  });
+  await page.getByTestId('test-tree').getByText('b.test.ts').click();
+  await page.keyboard.press('ArrowRight');
+  await page.getByTestId('test-tree').getByText('a.test.ts').click();
+  await page.keyboard.press('ArrowRight');
+  await expect.poll(dumpTestTree(page)).toBe(`
+    ▼ ◯ bar
+      ▼ ◯ b.test.ts
+          ◯ three
+          ◯ four
+    ▼ ◯ foo
+      ▼ ◯ a.test.ts <=
+          ◯ one
+          ◯ two
+  `);
+});
+
 test('should traverse up/down', async ({ runUITest }) => {
   const { page } = await runUITest(basicTestTree);
   await page.getByText('a.test.ts').click();