chore: adds missing test

tests/.snapshots/success.txt

@@ -2160,6 +2160,7 @@
   ✓ a parallel test can extend another test with same name
   ✓ parallel reports invalid datasets as failures
   ✓ parallel can have multiple exclude-groups
+  ✓ parallel can have multiple groups
 
    PASS  Tests\Visual\ParallelNestedDatasets
   ✓ parallel loads nested datasets from nested directories
@@ -2193,4 +2194,4 @@
   ✓ pass with dataset with ('my-datas-set-value')
   ✓ within describe → pass with dataset with ('my-datas-set-value')
 
-  Tests:    1 deprecated, 4 warnings, 5 incomplete, 2 notices, 40 todos, 35 skipped, 1547 passed (3381 assertions)
+  Tests:    1 deprecated, 4 warnings, 5 incomplete, 2 notices, 40 todos, 35 skipped, 1548 passed (3383 assertions)

tests/.tests/MultipleGroups/OneTest.php

@@ -0,0 +1,5 @@
+<?php
+
+it('belongs to group one', function () {
+    expect(true)->toBeTrue();
+})->group('one');

tests/.tests/MultipleGroups/ThreeTest.php

@@ -0,0 +1,5 @@
+<?php
+
+it('belongs to group three', function () {
+    expect(true)->toBeTrue();
+})->group('three');

tests/.tests/MultipleGroups/TwoTest.php

@@ -0,0 +1,5 @@
+<?php
+
+it('belongs to group two', function () {
+    expect(true)->toBeTrue();
+})->group('two');

tests/Visual/Parallel.php

@@ -58,3 +58,11 @@ test('parallel can have multiple exclude-groups', function () use ($run): void {
     expect((int) $doubleMatch[1])->toBeLessThan((int) $singleMatch[1])
         ->and($doubleExclude)->toContain('Parallel: 3 processes');
 })->skipOnWindows();
+
+test('parallel can have multiple groups', function () use ($run): void {
+    $output = $run('tests/.tests/MultipleGroups', '--group=one', '--group=two');
+
+    expect($output)
+        ->toContain('Tests:    2 passed (2 assertions)')
+        ->toContain('Parallel: 3 processes');
+})->skipOnWindows();