ByteSize.human_readable() should not have decimal point with B suffix (#4777)

ByteSize can only represent whole number of bytes, so displaying a
decimal would be misleading and doesn't really make sense in most cases
where ByteSize is used.

Outside pure mathematics, it is very rare to use non-whole number bytes.

Co-authored-by: Samuel Colvin <s@muelcolvin.com>

pydantic/types.py

@@ -694,7 +694,10 @@ class ByteSize(int):
         num = float(self)
         for unit in units:
             if abs(num) < divisor:
-                return f'{num:0.1f}{unit}'
+                if unit == 'B':
+                    return f'{num:0.0f}{unit}'
+                else:
+                    return f'{num:0.1f}{unit}'
             num /= divisor
 
         return f'{num:0.1f}{final_unit}'

tests/test_types.py

@@ -3252,9 +3252,9 @@ def test_frozenset_field_not_convertible():
 @pytest.mark.parametrize(
     'input_value,output,human_bin,human_dec',
     (
-        ('1', 1, '1.0B', '1.0B'),
-        ('1.0', 1, '1.0B', '1.0B'),
-        ('1b', 1, '1.0B', '1.0B'),
+        ('1', 1, '1B', '1B'),
+        ('1.0', 1, '1B', '1B'),
+        ('1b', 1, '1B', '1B'),
         ('1.5 KB', int(1.5e3), '1.5KiB', '1.5KB'),
         ('1.5 K', int(1.5e3), '1.5KiB', '1.5KB'),
         ('1.5 MB', int(1.5e6), '1.4MiB', '1.5MB'),