diff --git a/tests/appTest.php b/tests/appTest.php
new file mode 100644
index 0000000..8d86b6f
--- /dev/null
+++ b/tests/appTest.php
@@ -0,0 +1,132 @@
+<?php
+namespace nulib {
+  use nulib\tests\TestCase;
+  use nulib\impl\config;
+  use nulib\impl\myapp;
+  use nulib\impl\MyApplication1;
+  use nulib\impl\MyApplication2;
+
+  class appTest extends TestCase {
+    function testWith() {
+      $projdir = config::get_projdir();
+      $cwd = getcwd();
+
+      myapp::reset();
+      $app1 = myapp::with(MyApplication1::class);
+      self::assertSame([
+        "projdir" => $projdir,
+        "vendor" => [
+          "bindir" => "$projdir/vendor/bin",
+          "autoload" => "$projdir/vendor/autoload.php",
+        ],
+        "appcode" => "nur-sery",
+        "cwd" => $cwd,
+        "datadir" => "$projdir/devel",
+        "etcdir" => "$projdir/devel/etc",
+        "vardir" => "$projdir/devel/var",
+        "logdir" => "$projdir/devel/log",
+        "profile" => "devel",
+        "appgroup" => null,
+        "name" => "my-application1",
+        "title" => null,
+      ], $app1->getParams());
+
+      $app2 = myapp::with(MyApplication2::class, $app1);
+      self::assertSame([
+        "projdir" => $projdir,
+        "vendor" => [
+          "bindir" => "$projdir/vendor/bin",
+          "autoload" => "$projdir/vendor/autoload.php",
+        ],
+        "appcode" => "nur-sery",
+        "cwd" => $cwd,
+        "datadir" => "$projdir/devel",
+        "etcdir" => "$projdir/devel/etc",
+        "vardir" => "$projdir/devel/var",
+        "logdir" => "$projdir/devel/log",
+        "profile" => "devel",
+        "appgroup" => null,
+        "name" => "my-application2",
+        "title" => null,
+      ], $app2->getParams());
+    }
+
+    function testInit() {
+      $projdir = config::get_projdir();
+      $cwd = getcwd();
+
+      myapp::reset();
+      myapp::init(MyApplication1::class);
+      self::assertSame([
+        "projdir" => $projdir,
+        "vendor" => [
+          "bindir" => "$projdir/vendor/bin",
+          "autoload" => "$projdir/vendor/autoload.php",
+        ],
+        "appcode" => "nur-sery",
+        "cwd" => $cwd,
+        "datadir" => "$projdir/devel",
+        "etcdir" => "$projdir/devel/etc",
+        "vardir" => "$projdir/devel/var",
+        "logdir" => "$projdir/devel/log",
+        "profile" => "devel",
+        "appgroup" => null,
+        "name" => "my-application1",
+        "title" => null,
+      ], myapp::get()->getParams());
+
+      myapp::init(MyApplication2::class);
+      self::assertSame([
+        "projdir" => $projdir,
+        "vendor" => [
+          "bindir" => "$projdir/vendor/bin",
+          "autoload" => "$projdir/vendor/autoload.php",
+        ],
+        "appcode" => "nur-sery",
+        "cwd" => $cwd,
+        "datadir" => "$projdir/devel",
+        "etcdir" => "$projdir/devel/etc",
+        "vardir" => "$projdir/devel/var",
+        "logdir" => "$projdir/devel/log",
+        "profile" => "devel",
+        "appgroup" => null,
+        "name" => "my-application2",
+        "title" => null,
+      ], myapp::get()->getParams());
+    }
+  }
+}
+
+namespace nulib\impl {
+
+  use nulib\app\cli\Application;
+  use nulib\os\path;
+  use nulib\app;
+
+  class config {
+    const PROJDIR = __DIR__.'/..';
+
+    static function get_projdir(): string {
+      return path::abspath(self::PROJDIR);
+    }
+  }
+
+  class myapp extends app {
+    static function reset(): void {
+      self::$app = null;
+    }
+  }
+
+  class MyApplication1 extends Application {
+    const PROJDIR = config::PROJDIR;
+
+    function main() {
+    }
+  }
+  class MyApplication2 extends Application {
+    const PROJDIR = null;
+
+    function main() {
+    }
+  }
+}