diff --git a/Makefile b/Makefile
index 1d0d368..b31f823 100644
--- a/Makefile
+++ b/Makefile
@@ -26,7 +26,7 @@ default:
 ## PHP runtime ##
 
 # start PHP built-in webserver
-start: config/components-dev.local.php config/components-test.local.php backend/config/cookie-validation.key env.php
+start: config/components-dev.local.php backend/config/cookie-validation.key env.php
 	@echo "Starting server for api"
 	cd api && $(MAKE) start
 	@echo "Starting server for backend"
@@ -45,7 +45,7 @@ bash: cli
 cli:
 	$(DOCKER) bash
 
-start-docker: docker-compose.override.yml runtime/build-docker config/components-dev.local.php config/components-test.local.php backend/config/cookie-validation.key env.php stop
+start-docker: docker-compose.override.yml runtime/build-docker config/components-dev.local.php backend/config/cookie-validation.key env.php stop
 	docker-compose up -d
 	docker-compose exec -T backend-php bash -c "grep '^$(shell whoami):' /etc/passwd || useradd -m '$(shell whoami)' --uid=$(shell id -u) -G www-data -s /bin/bash -d /app/runtime/home"
 	docker-compose exec -T backend-php bash -c "sed -i 's/#force_color_prompt=yes/force_color_prompt=yes/' /app/runtime/home/.bashrc && sed -i 's~etc/bash_completion~etc/bash_completion.d/yii~' /app/runtime/home/.bashrc"
@@ -74,3 +74,19 @@ docker-compose.override.yml: docker-compose.override.dist.yml
 	test -f $@ || cp $< $@
 backend/config/cookie-validation.key:
 	test -s $@ || php -r 'echo bin2hex(random_bytes(20));' > $@
+
+
+## Docker Runtime Tests ##
+
+test: tests/_data/dump.sql
+	$(DOCKER) vendor/bin/codecept run
+
+clean:
+	rm -rf tests/_data/dump.sql
+
+# generate database dump for test env
+tests/_data/dump.sql: $(shell find common/migrations -type f)
+	$(DOCKER) sh -c 'YII_ENV=test ./yii migrate/fresh --interactive=0'
+	$(DOCKER) sh -c 'mysqldump -h db-test -uapi_test -papisecret api_db_test > tests/_data/dump.sql'
+	# for postgres you may use this command instead:
+	#$(DOCKER) sh -c 'PGPASSWORD=apisecret pg_dump --schema-only --clean --if-exists -w -h db-test -U api_test -d api_db_test -f tests/_data/dump.sql'
diff --git a/README.md b/README.md
index 799773c..54c29e1 100644
--- a/README.md
+++ b/README.md
@@ -77,6 +77,7 @@ You can now continue with [generating code](#generate-code).
 
 > Note: If you don't have GNU make, you need to copy the configuration files as in the PHP directly section, then run:
 > 
+>     cp docker-compose.override.dist.yml docker-compose.override.yml
 >     docker-compose up -d
 >     docker-compose exec backend-php sh -c 'cd /app && composer install'
 
diff --git a/backend/Dockerfile b/backend/Dockerfile
index d8394e5..0b3eac1 100644
--- a/backend/Dockerfile
+++ b/backend/Dockerfile
@@ -1,6 +1,6 @@
 FROM yiisoftware/yii2-php:7.4-apache
 
 # install git and unzip for composer install dist/source
-RUN apt-get update && apt-get -y install git unzip && apt-get clean && rm -rf /var/lib/apt/lists/*
+RUN apt-get update && apt-get -y install git unzip mariadb-client && apt-get clean && rm -rf /var/lib/apt/lists/*
 
 COPY config/apache.conf /etc/apache2/sites-enabled/000-default.conf
diff --git a/backend/config/components.php b/backend/config/components.php
index c3e510b..da51755 100644
--- a/backend/config/components.php
+++ b/backend/config/components.php
@@ -8,7 +8,9 @@
     'request' => [
         'cookieValidationKey' => file_get_contents(__DIR__ . '/cookie-validation.key'),
     ],
-
+    'errorHandler' => [
+        'errorAction' => 'site/error',
+    ],
     'urlManager' => [
         'enablePrettyUrl' => true,
         'enableStrictParsing' => true,
diff --git a/backend/controllers/SiteController.php b/backend/controllers/SiteController.php
index bcd4d87..77fa28d 100644
--- a/backend/controllers/SiteController.php
+++ b/backend/controllers/SiteController.php
@@ -3,12 +3,22 @@
 namespace backend\controllers;
 
 use yii\web\Controller;
+use yii\web\ErrorAction;
 
 /**
  *
  */
 class SiteController extends Controller
 {
+    public function actions()
+    {
+        return array_merge(parent::actions(), [
+            'error' => [
+                'class' => ErrorAction::class,
+            ],
+        ]);
+    }
+
     public function actionIndex()
     {
         return $this->render('index');
diff --git a/codeception.yml b/codeception.yml
new file mode 100644
index 0000000..e52ee21
--- /dev/null
+++ b/codeception.yml
@@ -0,0 +1,38 @@
+# suite config
+suites:
+    api:
+        actor: ApiTester
+        path: api/
+        bootstrap: 'bootstrap.php'
+        modules:
+            enabled:
+                - Asserts
+                - Db:
+                      dsn: mysql:host=db-test;dbname=api_db_test
+                      user: api_test
+                      password: apisecret
+                      # tests/_data/dump.sql is generated by Makefile: make tests/_data/dump.sql
+                      dump: '/app/tests/_data/dump.sql'
+                      populator: 'mysql -h $host -u$user -p$password $dbname < $dump'
+                      populate: true
+                      cleanup: true
+                      reconnect: true
+                      waitlock: 10
+                # Yii2 module must be loaded after Db module to make sure fixtures are not overwritten by Db dump
+                - Yii2:
+                    configFile: 'api/config/app-test.php'
+                - REST:
+                    #url: http://api-php-test:80/
+                    depends: Yii2
+        step_decorators:
+            - \Codeception\Step\AsJson
+
+paths:
+    tests: tests
+    output: tests/_output
+    data: tests/_data
+    support: tests/_support
+
+settings:
+    shuffle: false
+    lint: true
\ No newline at end of file
diff --git a/composer.json b/composer.json
index e214961..b2394fb 100644
--- a/composer.json
+++ b/composer.json
@@ -10,6 +10,14 @@
         "cebe/yii2-openapi": "^2.0@beta",
         "yiisoft/yii2-gii": "^2.1"
     },
+    "require-dev": {
+        "codeception/codeception": "^4.2",
+        "codeception/module-phpbrowser": "^1.0.0",
+        "codeception/module-asserts": "^1.0.0",
+        "codeception/module-rest": "^1.0.0",
+        "codeception/module-yii2": "^1.1",
+        "codeception/module-db": "^1.2"
+    },
     "autoload": {
         "psr-4": {
             "api\\": "api/",
@@ -19,7 +27,9 @@
         }
     },
     "config": {
-        "platform": {"php": "7.1.3"},
+        "platform": {
+            "php": "7.1.3"
+        },
         "fxp-asset": {
             "enabled": false
         },
diff --git a/config/components-test.php b/config/components-test.php
index b2eb8f2..3df93f6 100644
--- a/config/components-test.php
+++ b/config/components-test.php
@@ -11,6 +11,14 @@
         'class' => \yii\swiftmailer\Mailer::class,
         'useFileTransport' => true,
     ],
+    'db' => [
+        'class' => yii\db\Connection::class,
+        'dsn' => 'mysql:host=db-test;dbname=api_db_test', // for docker
+        //'dsn' => 'mysql:host=localhost;dbname=api_db_test', // use this when mysql runs on your local host
+        'username' => 'api_test',
+        'password' => 'apisecret',
+        'charset' => 'utf8',
+    ],
 ],
 
 file_exists($localConfig = __DIR__ . '/components-test.local.php') ? require $localConfig : []
diff --git a/config/env.php b/config/env.php
index 61c6ed0..d53ac6b 100644
--- a/config/env.php
+++ b/config/env.php
@@ -1,7 +1,11 @@
 <?php
 
 if (!defined('YII_ENV')) {
-    if (is_file($env = __DIR__ . '/../env.php')) {
+    // allow setting YII ENV via environment, load it from local config if no env is set
+    if (getenv('YII_ENV')) {
+        define('YII_ENV', strtolower(getenv('YII_ENV')));
+        define('YII_DEBUG', YII_ENV === 'dev' || YII_ENV === 'test');
+    } elseif (is_file($env = __DIR__ . '/../env.php')) {
         include($env);
     } else {
         define('YII_DEBUG', false);
diff --git a/docker-compose.yml b/docker-compose.yml
index 99456ee..9c4795a 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -6,8 +6,6 @@ version: '2'
 services:
   api-php:
     build: api
-    ports:
-      - '8337:80'
     volumes:
       # Mount source-code for development
       - ./:/app
@@ -18,8 +16,6 @@ services:
 
   backend-php:
     build: backend
-    ports:
-      - '8338:80'
     volumes:
       # Re-use local composer cache via host-volume
       - ~/.composer-docker/cache:/root/.composer/cache:delegated
@@ -38,10 +34,17 @@ services:
       - MARIADB_USER=api
       - MARIADB_PASSWORD=apisecret
 
+  db-test:
+    image: mariadb:10.8
+    environment:
+      - MARIADB_ROOT_PASSWORD=verysecret
+      - MARIADB_DATABASE=api_db_test
+      - MARIADB_USER=api_test
+      - MARIADB_PASSWORD=apisecret
+
   redis:
     image: redis:3
 
   mailcatcher:
     image: nisenabe/mailcatcher
-    ports:
-      - '8055:1080'
+
diff --git a/tests/_data/.gitignore b/tests/_data/.gitignore
new file mode 100644
index 0000000..835f25d
--- /dev/null
+++ b/tests/_data/.gitignore
@@ -0,0 +1 @@
+/dump.sql
\ No newline at end of file
diff --git a/tests/_output/.gitignore b/tests/_output/.gitignore
new file mode 100644
index 0000000..c96a04f
--- /dev/null
+++ b/tests/_output/.gitignore
@@ -0,0 +1,2 @@
+*
+!.gitignore
\ No newline at end of file
diff --git a/tests/_support/ApiTester.php b/tests/_support/ApiTester.php
new file mode 100644
index 0000000..968d04b
--- /dev/null
+++ b/tests/_support/ApiTester.php
@@ -0,0 +1,26 @@
+<?php
+
+
+/**
+ * Inherited Methods
+ * @method void wantToTest($text)
+ * @method void wantTo($text)
+ * @method void execute($callable)
+ * @method void expectTo($prediction)
+ * @method void expect($prediction)
+ * @method void amGoingTo($argumentation)
+ * @method void am($role)
+ * @method void lookForwardTo($achieveValue)
+ * @method void comment($description)
+ * @method void pause()
+ *
+ * @SuppressWarnings(PHPMD)
+*/
+class ApiTester extends \Codeception\Actor
+{
+    use _generated\ApiTesterActions;
+
+    /**
+     * Define custom actions here
+     */
+}
diff --git a/tests/_support/Helper/Api.php b/tests/_support/Helper/Api.php
new file mode 100644
index 0000000..7a4621e
--- /dev/null
+++ b/tests/_support/Helper/Api.php
@@ -0,0 +1,10 @@
+<?php
+namespace Helper;
+
+// here you can define custom actions
+// all public methods declared in helper class will be available in $I
+
+class Api extends \Codeception\Module
+{
+
+}
diff --git a/tests/_support/_generated/.gitignore b/tests/_support/_generated/.gitignore
new file mode 100644
index 0000000..c96a04f
--- /dev/null
+++ b/tests/_support/_generated/.gitignore
@@ -0,0 +1,2 @@
+*
+!.gitignore
\ No newline at end of file
diff --git a/tests/api/ApiCest.php b/tests/api/ApiCest.php
new file mode 100644
index 0000000..81de50c
--- /dev/null
+++ b/tests/api/ApiCest.php
@@ -0,0 +1,12 @@
+<?php
+class ApiCest 
+{    
+    public function tryApi(ApiTester $I)
+    {
+        $I->sendGet('/');
+        $I->seeResponseCodeIs(404);
+        $I->seeResponseIsJson();
+    }
+
+    // TODO add more tests
+}
diff --git a/tests/api/bootstrap.php b/tests/api/bootstrap.php
new file mode 100644
index 0000000..b55fa3b
--- /dev/null
+++ b/tests/api/bootstrap.php
@@ -0,0 +1,3 @@
+<?php
+
+require(__DIR__ . '/../../config/env.php');