Helper tweaks (#10131)

* Enhance report tags

* Update docs

src/backend/InvenTree/report/templatetags/report.py

@@ -393,27 +393,27 @@ def internal_link(link, text) -> str:
 
 
 @register.simple_tag()
-def add(x, y, *args, **kwargs):
+def add(x: float, y: float, *args, **kwargs) -> float:
     """Add two numbers together."""
-    return x + y
+    return float(x) + float(y)
 
 
 @register.simple_tag()
-def subtract(x, y):
+def subtract(x: float, y: float) -> float:
     """Subtract one number from another."""
-    return x - y
+    return float(x) - float(y)
 
 
 @register.simple_tag()
-def multiply(x, y):
+def multiply(x: float, y: float) -> float:
     """Multiply two numbers together."""
-    return x * y
+    return float(x) * float(y)
 
 
 @register.simple_tag()
-def divide(x, y):
+def divide(x: float, y: float) -> float:
     """Divide one number by another."""
-    return x / y
+    return float(x) / float(y)
 
 
 @register.simple_tag

src/backend/InvenTree/report/test_tags.py

@@ -197,10 +197,15 @@ class ReportTagTest(PartImageTestMixin, InvenTreeTestCase):
     def test_maths_tags(self):
         """Simple tests for mathematical operator tags."""
         self.assertEqual(report_tags.add(1, 2), 3)
+        self.assertEqual(report_tags.add('-33', '33'), 0)
         self.assertEqual(report_tags.subtract(10, 4.2), 5.8)
         self.assertEqual(report_tags.multiply(2.3, 4), 9.2)
+        self.assertEqual(report_tags.multiply('-2', 4), -8.0)
         self.assertEqual(report_tags.divide(100, 5), 20)
 
+        with self.assertRaises(ZeroDivisionError):
+            report_tags.divide(100, 0)
+
     def test_number_tags(self):
         """Simple tests for number formatting tags."""
         fn = report_tags.format_number