feat(app): add sanity checks for env variables

app/apps/common/apps.py

@@ -23,3 +23,6 @@ class CommonConfig(AppConfig):
         # Delete the cache for update checks to prevent false-positives when the app is restarted
         # this will be recreated by the check_for_updates task
         cache.delete("update_check")
+
+        # Register system checks for required environment variables
+        from apps.common import checks  # noqa: F401

app/apps/common/checks.py

@@ -0,0 +1,103 @@
+"""
+Django System Checks for required environment variables.
+
+This module validates that required environment variables (those without defaults)
+are present before the application starts.
+"""
+
+import os
+
+from django.core.checks import Error, register
+
+
+# List of environment variables that are required (no default values)
+# Based on the README.md documentation
+REQUIRED_ENV_VARS = [
+    ("SECRET_KEY", "This is used to provide cryptographic signing."),
+    ("SQL_DATABASE", "The name of your postgres database."),
+]
+
+# List of environment variables that must be valid integers if set
+INT_ENV_VARS = [
+    ("TASK_WORKERS", "How many workers to have for async tasks."),
+    ("SESSION_EXPIRY_TIME", "The age of session cookies, in seconds."),
+    ("INTERNAL_PORT", "The port on which the app listens on."),
+    ("DJANGO_VITE_DEV_SERVER_PORT", "The port where Vite's dev server is running"),
+]
+
+
+@register()
+def check_required_env_vars(app_configs, **kwargs):
+    """
+    Check that all required environment variables are set.
+
+    Returns a list of Error objects for any missing required variables.
+    """
+    errors = []
+
+    for var_name, description in REQUIRED_ENV_VARS:
+        value = os.getenv(var_name)
+        if not value:
+            errors.append(
+                Error(
+                    f"Required environment variable '{var_name}' is not set.",
+                    hint=f"{description} Please set this variable in your .env file or environment.",
+                    id="wygiwyh.E001",
+                )
+            )
+
+    return errors
+
+
+@register()
+def check_int_env_vars(app_configs, **kwargs):
+    """
+    Check that environment variables that should be integers are valid.
+
+    Returns a list of Error objects for any invalid integer variables.
+    """
+    errors = []
+
+    for var_name, description in INT_ENV_VARS:
+        value = os.getenv(var_name)
+        if value is not None:
+            try:
+                int(value)
+            except ValueError:
+                errors.append(
+                    Error(
+                        f"Environment variable '{var_name}' must be a valid integer, got '{value}'.",
+                        hint=f"{description}",
+                        id="wygiwyh.E002",
+                    )
+                )
+
+    return errors
+
+
+@register()
+def check_soft_delete_config(app_configs, **kwargs):
+    """
+    Check that KEEP_DELETED_TRANSACTIONS_FOR is a valid integer when ENABLE_SOFT_DELETE is enabled.
+
+    Returns a list of Error objects if the configuration is invalid.
+    """
+    errors = []
+
+    enable_soft_delete = os.getenv("ENABLE_SOFT_DELETE", "false").lower() == "true"
+
+    if enable_soft_delete:
+        keep_deleted_for = os.getenv("KEEP_DELETED_TRANSACTIONS_FOR")
+        if keep_deleted_for is not None:
+            try:
+                int(keep_deleted_for)
+            except ValueError:
+                errors.append(
+                    Error(
+                        f"Environment variable 'KEEP_DELETED_TRANSACTIONS_FOR' must be a valid integer when ENABLE_SOFT_DELETE is enabled, got '{keep_deleted_for}'.",
+                        hint="Time in days to keep soft deleted transactions for. Set to 0 to keep all transactions indefinitely.",
+                        id="wygiwyh.E003",
+                    )
+                )
+
+    return errors

app/apps/import_app/tests/test_import_service_v1.py

@@ -8,7 +8,6 @@ is only used for string fields (not dates, decimals, etc.).
 
 from datetime import date
 from decimal import Decimal
-from unittest.mock import MagicMock, patch
 
 from django.test import TestCase