diff --git a/tests/Unit/Middleware/WithoutOverlappingMiddlewareTest.php b/tests/Unit/Middleware/WithoutOverlappingMiddlewareTest.php
index c0502a2b..7fe65714 100644
--- a/tests/Unit/Middleware/WithoutOverlappingMiddlewareTest.php
+++ b/tests/Unit/Middleware/WithoutOverlappingMiddlewareTest.php
@@ -4,6 +4,8 @@
 
 namespace Tests\Unit\Middleware;
 
+use Illuminate\Contracts\Cache\Lock;
+use Illuminate\Contracts\Cache\Repository;
 use Illuminate\Support\Facades\Cache;
 use Mockery\MockInterface;
 use Tests\Fixtures\TestActivity;
@@ -111,4 +113,60 @@ public function testAllowsMultipleActivityInstances(): void
         $this->assertNull(Cache::get($middleware1->getWorkflowSemaphoreKey()));
         $this->assertSame(0, count(Cache::get($middleware1->getActivitySemaphoreKey())));
     }
+
+    public function testUnknownTypeDoesNotCallNext(): void
+    {
+        $this->app->make('cache')
+            ->store()
+            ->clear();
+
+        $job = $this->mock(TestActivity::class, static function (MockInterface $mock) {
+            $mock->shouldReceive('release')
+                ->once();
+        });
+
+        $middleware = new WithoutOverlappingMiddleware(1, 999);
+
+        $middleware->handle($job, function ($job) {
+            $this->fail('Should not call next when type is unknown');
+        });
+
+        $this->assertNull(Cache::get($middleware->getWorkflowSemaphoreKey()));
+        $this->assertNull(Cache::get($middleware->getActivitySemaphoreKey()));
+    }
+
+    public function testReleaseWhenCompareAndSetFails(): void
+    {
+        $this->app->make('cache')
+            ->store()
+            ->clear();
+
+        $job = $this->mock(TestWorkflow::class, static function (MockInterface $mock) {
+            $mock->shouldReceive('release')
+                ->once();
+        });
+
+        $lock = $this->mock(Lock::class, static function (MockInterface $mock) {
+            $mock->shouldReceive('get')
+                ->once()
+                ->andReturn(false);
+        });
+
+        $cache = $this->mock(Repository::class, static function (MockInterface $mock) use ($lock) {
+            $mock->shouldReceive('lock')
+                ->once()
+                ->andReturn($lock);
+            $mock->shouldReceive('get')
+                ->andReturn([]);
+        });
+
+        $middleware = new WithoutOverlappingMiddleware(1, WithoutOverlappingMiddleware::WORKFLOW);
+
+        $middleware->handle($job, function ($job) {
+            $this->fail('Should not call next when lock is not acquired');
+        });
+
+        $this->assertNull(Cache::get($middleware->getWorkflowSemaphoreKey()));
+        $this->assertNull(Cache::get($middleware->getActivitySemaphoreKey()));
+    }
 }
diff --git a/tests/Unit/Serializers/SerializeTest.php b/tests/Unit/Serializers/SerializeTest.php
index 3f35e541..399e0386 100644
--- a/tests/Unit/Serializers/SerializeTest.php
+++ b/tests/Unit/Serializers/SerializeTest.php
@@ -58,6 +58,13 @@ public static function dataProvider(): array
         ];
     }
 
+    public function testSerializableReturnsFalseForClosure(): void
+    {
+        $this->assertFalse(Serializer::serializable(static function () {
+            return 'test';
+        }));
+    }
+
     private function testSerializeUnserialize($data, $serializer, $unserializer): void
     {
         config([
diff --git a/tests/Unit/Traits/MonitorQueueConnectionTest.php b/tests/Unit/Traits/MonitorQueueConnectionTest.php
new file mode 100644
index 00000000..f3756d02
--- /dev/null
+++ b/tests/Unit/Traits/MonitorQueueConnectionTest.php
@@ -0,0 +1,67 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Unit\Traits;
+
+use Tests\TestCase;
+use Workflow\Traits\MonitorQueueConnection;
+
+class MonitorQueueConnectionTest extends TestCase
+{
+    public function testReturnsDefaultConnection(): void
+    {
+        config([
+            'queue.default' => 'sync',
+            'workflows.monitor_connection' => config('queue.default'),
+        ]);
+
+        $instance = $this->makeAnonymousTraitInstance();
+
+        $this->assertSame(config('queue.default'), $instance->viaConnection());
+    }
+
+    public function testReturnsDefaultQueue(): void
+    {
+        config([
+            'queue.default' => 'sync',
+            'workflows.monitor_connection' => config('queue.default'),
+        ]);
+
+        $instance = $this->makeAnonymousTraitInstance();
+
+        $this->assertSame('default', $instance->viaQueue());
+    }
+
+    public function testReturnsCustomConnection(): void
+    {
+        config([
+            'queue.default' => 'sync',
+            'workflows.monitor_connection' => 'custom_connection',
+        ]);
+
+        $instance = $this->makeAnonymousTraitInstance();
+
+        $this->assertSame('custom_connection', $instance->viaConnection());
+    }
+
+    public function testReturnsCustomQueue(): void
+    {
+        config([
+            'queue.default' => 'sync',
+            'workflows.monitor_connection' => config('queue.default'),
+            'workflows.monitor_queue' => 'custom_queue',
+        ]);
+
+        $instance = $this->makeAnonymousTraitInstance();
+
+        $this->assertSame('custom_queue', $instance->viaQueue());
+    }
+
+    private function makeAnonymousTraitInstance(): object
+    {
+        return new class() {
+            use MonitorQueueConnection;
+        };
+    }
+}
diff --git a/tests/Unit/migrations/MigrationsTest.php b/tests/Unit/migrations/MigrationsTest.php
new file mode 100644
index 00000000..ae24cc0b
--- /dev/null
+++ b/tests/Unit/migrations/MigrationsTest.php
@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Unit\Migrations;
+
+use Illuminate\Support\Facades\Schema;
+use Tests\TestCase;
+
+final class MigrationsTest extends TestCase
+{
+    public function testDownMethodsDropTables(): void
+    {
+        $this->assertTrue(Schema::hasTable('workflows'));
+        $this->assertTrue(Schema::hasTable('workflow_logs'));
+        $this->assertTrue(Schema::hasTable('workflow_signals'));
+        $this->assertTrue(Schema::hasTable('workflow_timers'));
+        $this->assertTrue(Schema::hasTable('workflow_exceptions'));
+        $this->assertTrue(Schema::hasTable('workflow_relationships'));
+
+        $this->artisan('migrate:reset', [
+            '--path' => dirname(__DIR__, 3) . '/src/migrations',
+            '--realpath' => true,
+        ])->run();
+
+        $this->assertFalse(Schema::hasTable('workflows'));
+        $this->assertFalse(Schema::hasTable('workflow_logs'));
+        $this->assertFalse(Schema::hasTable('workflow_signals'));
+        $this->assertFalse(Schema::hasTable('workflow_timers'));
+        $this->assertFalse(Schema::hasTable('workflow_exceptions'));
+        $this->assertFalse(Schema::hasTable('workflow_relationships'));
+    }
+}
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 00d2f112..25b78bcc 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -3,7 +3,6 @@
 declare(strict_types=1);
 
 require_once __DIR__ . '/../vendor/autoload.php';
-require_once __DIR__ . '/classAliases.php';
 
 use PHPUnit\Event\Facade;
 use Tests\TestSuiteSubscriber;