Allow fractional interval argument for database worker

django_tasks/backends/database/management/commands/db_worker.py

@@ -1,4 +1,5 @@
 import logging
+import math
 import random
 import signal
 import sys
@@ -158,10 +159,9 @@ def valid_backend_name(val: str) -> str:
 
 
 def valid_interval(val: str) -> float:
-    # Cast to an int first to catch invalid values like 'inf'
-    int(val)
-
     num = float(val)
+    if not math.isfinite(num):
+        raise ArgumentTypeError("Must be a finite floating point value")
     if num < 0:
         raise ArgumentTypeError("Must be greater than zero")
     return num

tests/tests/test_database_backend.py

@@ -5,7 +5,7 @@
 from functools import partial
 from io import StringIO
 from typing import Sequence, Union, cast
-from unittest import skipIf
+from unittest import mock, skipIf
 
 from django.core.exceptions import SuspiciousOperation
 from django.core.management import call_command, execute_from_command_line
@@ -426,7 +426,17 @@ def test_infinite_interval(self) -> None:
                 execute_from_command_line(
                     ["django-admin", "db_worker", "--interval", "inf"]
                 )
-        self.assertIn("invalid valid_interval value: 'inf'", output.getvalue())
+        self.assertIn("Must be a finite floating point value", output.getvalue())
+
+    def test_fractional_interval(self) -> None:
+        with mock.patch(
+            "django_tasks.backends.database.management.commands.db_worker.Worker"
+        ) as worker_class:
+            execute_from_command_line(
+                ["django-admin", "db_worker", "--interval", "0.1"]
+            )
+
+        self.assertEqual(worker_class.mock_calls[0].kwargs["interval"], 0.1)
 
     def test_run_after(self) -> None:
         result = test_tasks.noop_task.using(