fix: int_to_roman silently returns wrong values for out-of-range input

conversions/roman_numerals.py

@@ -40,12 +40,35 @@ def roman_to_int(roman: str) -> int:
 
 def int_to_roman(number: int) -> str:
     """
-    Given a integer, convert it to an roman numeral.
+    Given an integer, convert it to a Roman numeral.
+    Input must be an integer in the range 1 to 3999.
     https://en.wikipedia.org/wiki/Roman_numerals
     >>> tests = {"III": 3, "CLIV": 154, "MIX": 1009, "MMD": 2500, "MMMCMXCIX": 3999}
     >>> all(int_to_roman(value) == key for key, value in tests.items())
     True
+    >>> int_to_roman(0)
+    Traceback (most recent call last):
+        ...
+    ValueError: int_to_roman only accepts integers in the range 1 to 3999, got 0
+    >>> int_to_roman(-1)
+    Traceback (most recent call last):
+        ...
+    ValueError: int_to_roman only accepts integers in the range 1 to 3999, got -1
+    >>> int_to_roman(4000)
+    Traceback (most recent call last):
+        ...
+    ValueError: int_to_roman only accepts integers in the range 1 to 3999, got 4000
+    >>> int_to_roman(True)
+    Traceback (most recent call last):
+        ...
+    TypeError: int_to_roman only accepts integers, got bool
     """
+    if not isinstance(number, int) or isinstance(number, bool):
+        msg = f"int_to_roman only accepts integers, got {type(number).__name__}"
+        raise TypeError(msg)
+    if not 1 <= number <= 3999:
+        msg = f"int_to_roman only accepts integers in the range 1 to 3999, got {number}"
+        raise ValueError(msg)
     result = []
     for arabic, roman in ROMAN:
         (factor, number) = divmod(number, arabic)