tests for DB connect

app/app/settings.py

@@ -11,6 +11,7 @@
 """
 
 from pathlib import Path
+import os
 
 # Build paths inside the project like this: BASE_DIR / 'subdir'.
 BASE_DIR = Path(__file__).resolve().parent.parent
@@ -37,6 +38,7 @@
     'django.contrib.sessions',
     'django.contrib.messages',
     'django.contrib.staticfiles',
+    'core',
 ]
 
 MIDDLEWARE = [
@@ -75,8 +77,11 @@
 
 DATABASES = {
     'default': {
-        'ENGINE': 'django.db.backends.sqlite3',
-        'NAME': BASE_DIR / 'db.sqlite3',
+        'ENGINE': 'django.db.backends.postgresql',
+        'HOST': os.environ.get('DB_HOST'),
+        'NAME': os.environ.get('DB_NAME'),
+        'USER': os.environ.get('DB_USER'),
+        'PASSWORD': os.environ.get('DB_PASS')
     }
 }
 

app/core/admin.py

@@ -0,0 +1,3 @@
+from django.contrib import admin
+
+# Register your models here.

app/core/apps.py

@@ -0,0 +1,6 @@
+from django.apps import AppConfig
+
+
+class CoreConfig(AppConfig):
+    default_auto_field = 'django.db.models.BigAutoField'
+    name = 'core'

app/core/management/commands/wait_for_db.py

@@ -0,0 +1,13 @@
+"""
+Django command for the database to be available.
+"""
+
+from typing import Any
+from django.core.management import BaseCommand
+
+
+class Command(BaseCommand):
+    """Django command to wait for database"""
+
+    def handle(self, *args: Any, **options: Any):
+        pass

app/core/models.py

@@ -0,0 +1,3 @@
+from django.db import models
+
+# Create your models here.

app/core/tests/test_commands.py

@@ -0,0 +1,34 @@
+"""
+Test custom Django management commands.
+"""
+from unittest.mock import patch
+
+from psycopg2 import OperationalError as Psycopg2OpError
+
+from django.core.management import call_command
+from django.db.utils import OperationalError
+from django.test import SimpleTestCase
+
+
+@patch('core.management.commands.wait_for_db.Command.check')
+class CommandTests(SimpleTestCase):
+    """Test commands."""
+
+    def test_wait_for_db_ready(self, patched_check):
+        """Test waiting for database if database ready."""
+        patched_check.return_value = True
+
+        call_command('wait_for_db')
+
+        patched_check.assert_called_once_with(databases=['default'])
+
+    @patch('time.sleep')
+    def test_wait_for_db_delay(self, patched_sleep, patched_check):
+        """Test waiting for database when getting OperationalError."""
+        patched_check.side_effect = [Psycopg2OpError] * 2 + \
+            [OperationalError] * 3 + [True]
+
+        call_command('wait_for_db')
+
+        self.assertEqual(patched_check.call_count, 6)
+        patched_check.assert_called_with(databases=['default'])

docker-compose.yml

@@ -8,7 +8,7 @@ services:
         - DEV=true
     ports:
       - "8000:8000"
-    volumes:
+    volumes: 
       - ./app:/app
     command: >
       sh -c "python manage.py runserver 0.0.0.0:8000"

requirements.txt

@@ -1,2 +1,3 @@
 Django>=3.2.0,<3.3
-djangorestframework>=3.12.4,<3.13
+djangorestframework>=3.12.4,<3.13
+psycopg2>=2.8.6,<2.9