Revert "test: remove fragile worker distribution test"

This reverts commit 5c03e7a.

Author: mirao

test/unit/worker_test.js

@@ -383,4 +383,33 @@ describe('Workers', function () {
     workers.run()
   })
 
+  it('should distribute suites across workers for --by suite (issue #5412)', async () => {
+    // This test verifies the fix for issue #5412:
+    // Test files should NOT be sorted in loadTests() because that affects worker distribution.
+    // Sorting should only happen in run() for execution order.
+    //
+    // The bug was: sorting in loadTests() changed the order of suites during distribution,
+    // causing all workers to receive the same tests instead of different suites.
+
+    // Ensure clean state
+    Container.clear()
+    Container.createMocha()
+
+    const workerConfig = {
+      by: 'suite',
+      testConfig: './test/data/sandbox/codecept.customworker.js',
+    }
+
+    const workers = new Workers(3, workerConfig)
+    await workers._ensureInitialized()
+
+    // Verify that test files were loaded
+    const testFiles = workers.codecept.testFiles
+    expect(testFiles.length).to.be.greaterThan(0, 'Test files should be loaded')
+
+    // Verify that suites are distributed across multiple worker groups
+    const groups = workers.testGroups
+    const nonEmptyGroups = groups.filter(g => g.length > 0)
+    expect(nonEmptyGroups.length).to.be.greaterThan(1, 'Suites should be distributed across multiple worker groups')
+  })
 })