fix: parallel runs with group filters no longer exit 1 despite green tests

src/Plugins/Parallel/Paratest/WrapperRunner.php

@@ -323,8 +323,18 @@ private function complete(TestResult $testResultSum): int
             /** @var list<AfterLastTestMethodFailed> $failedEvents */
             $failedEvents = array_merge_recursive($testResultSum->testFailedEvents(), $testResult->testFailedEvents());
 
+            // A worker's `hasTests()` only reflects the *last* file it executed:
+            // PHPUnit's Collector overwrites `numberOfTests` on every
+            // `executionStarted` event. When a worker's final file has all of
+            // its tests excluded by `--group`/`--exclude-group`, that worker
+            // reports `hasTests() === false` even though it ran plenty of
+            // tests. If every worker happens to end on such a file, the merged
+            // result claims the whole suite was empty and the run exits 1
+            // (PHPUnit enables `failOnEmptyTestSuite` implicitly for explicit
+            // test selections) — despite a fully green summary. Treating a
+            // worker with executed tests as "has tests" restores the truth.
             $testResultSum = new TestResult(
-                (int) $testResultSum->hasTests() + (int) $testResult->hasTests(),
+                (int) ($testResultSum->hasTests() || $testResult->hasTests() || $testResult->numberOfTestsRun() > 0),
                 $testResultSum->numberOfTestsRun() + $testResult->numberOfTestsRun(),
                 $testResultSum->numberOfAssertions() + $testResult->numberOfAssertions(),
                 array_merge_recursive($testResultSum->testErroredEvents(), $testResult->testErroredEvents()),

tests/.tests/ParallelGroupFilteredLastFile/ATest.php

@@ -0,0 +1,5 @@
+<?php
+
+test('a test inside the filtered group', function () {
+    expect(true)->toBeTrue();
+})->group('filtered-group');

tests/.tests/ParallelGroupFilteredLastFile/ZTest.php

@@ -0,0 +1,5 @@
+<?php
+
+test('a test outside the filtered group', function () {
+    expect(true)->toBeTrue();
+});

tests/Visual/Parallel.php

@@ -47,3 +47,38 @@
         ->toContain('Tests:    1 failed, 1 passed (1 assertions)')
         ->toContain('Parallel: 3 processes');
 })->skipOnWindows();
+
+test('parallel group-filtered run is not considered empty when workers end on fully filtered files', function () {
+    // Regression: a worker's TestResult only carries `numberOfTests` of its
+    // LAST executed file (PHPUnit's Collector overwrites it per execution).
+    // With `--processes=1` the single worker deterministically ends on
+    // ZTest.php, whose only test is excluded by the group filter — before the
+    // fix the merged result claimed "no tests" and exited 1 despite the green
+    // summary (PHPUnit enables failOnEmptyTestSuite implicitly for --group).
+    $process = new Process(
+        ['php', 'bin/pest', '--parallel', '--processes=1', '--group=filtered-group', 'tests/.tests/ParallelGroupFilteredLastFile'],
+        dirname(__DIR__, 2),
+        ['COLLISION_PRINTER' => 'DefaultPrinter', 'COLLISION_IGNORE_DURATION' => 'true'],
+    );
+
+    $process->run();
+
+    expect(removeAnsiEscapeSequences($process->getOutput()))
+        ->toContain('Tests:    1 passed (1 assertions)');
+
+    expect($process->getExitCode())->toBe(0);
+})->skipOnWindows();
+
+test('parallel group-filtered run still fails when the selection matches no tests at all', function () {
+    // Companion guard: a genuinely empty selection must keep exiting non-zero
+    // (failOnEmptyTestSuite) — the fix must not mask real "0 tests" runs.
+    $process = new Process(
+        ['php', 'bin/pest', '--parallel', '--processes=3', '--group=group-that-does-not-exist', 'tests/.tests/ParallelGroupFilteredLastFile'],
+        dirname(__DIR__, 2),
+        ['COLLISION_PRINTER' => 'DefaultPrinter', 'COLLISION_IGNORE_DURATION' => 'true'],
+    );
+
+    $process->run();
+
+    expect($process->getExitCode())->not->toBe(0);
+})->skipOnWindows();