Fix ordinal() suffix for negative integers

ordinal() selected the suffix using value % 10 and value % 100, but
Python's modulo on negative numbers is non-negative (e.g. -1 % 10 == 9),
so negative inputs got the wrong suffix: ordinal(-1) returned '-1th'
instead of '-1st', ordinal(-21) returned '-21th' instead of '-21st', etc.

The docstring states it works for any integer, so compute the suffix
from abs(value). Add regression tests for negative ordinals.

Author: fbindakheel

src/humanize/number.py

@@ -107,7 +107,11 @@ def ordinal(value: NumberOrString, gender: str = "male") -> str:
     except (TypeError, ValueError):
         return str(value)
     gender = "male" if gender == "male" else "female"
-    digit = 0 if value % 100 in (11, 12, 13) else value % 10
+    # Use the magnitude for suffix selection: Python's modulo on negative
+    # numbers is non-negative (e.g. -1 % 10 == 9), which would otherwise
+    # pick the wrong suffix and produce "-1th" instead of "-1st".
+    abs_value = abs(value)
+    digit = 0 if abs_value % 100 in (11, 12, 13) else abs_value % 10
     return f"{value}{P_(f'{digit} ({gender})', _ORDINAL_SUFFIXES[digit])}"
 
 

tests/test_number.py

@@ -25,6 +25,16 @@
         ("102", "102nd"),
         ("103", "103rd"),
         ("111", "111th"),
+        ("-1", "-1st"),
+        ("-2", "-2nd"),
+        ("-3", "-3rd"),
+        ("-4", "-4th"),
+        ("-11", "-11th"),
+        ("-12", "-12th"),
+        ("-13", "-13th"),
+        ("-21", "-21st"),
+        ("-101", "-101st"),
+        ("-111", "-111th"),
         ("something else", "something else"),
         (None, "None"),
         (math.nan, "NaN"),