Introduce exactness into Decimal validation logic

[sydney-runkle]

Fix pydantic/pydantic#10142
Fix pydantic/pydantic#9795

Introducing exactness into various validation cases makes smart union validation better - we no longer match str input as exact, but rather lax.

[codspeed-hq]

CodSpeed Performance Report

Merging #1405 will not alter performance

_{Comparing decimal-val-fix (b70b330) with main (fdd1e85)}

Summary

✅ 155 untouched benchmarks

[davidhewitt]

Overall lgtm with a suggestion for a simplification...

[davidhewitt]

Some further thoughts :)

[davidhewitt]

This was deliberately below the PyString / PyInt / PyBool check because those are faster to check for (see comment now on line 334), maybe move those up (but have them with a !strict guard too).

[davidhewitt]

I wonder if Str should be strict... we serialize decimals as strings now, correct?

[sydney-runkle]

Ah, ok! What about floats and ints, should those be strict as well?

[sydney-runkle]

Is anything lax then?

[davidhewitt]

I guess they're probably all strict? Ungh 😂

[sydney-runkle]

So we don't need lax hahah

[sydney-runkle]

For Python, I think they should be lax, based on existing tests...

[sydney-runkle]

@pytest.mark.parametrize(
    'input_value,expected',
    [
        (Decimal(0), Decimal(0)),
        (Decimal(1), Decimal(1)),
        (Decimal(42), Decimal(42)),
        (Decimal('42.0'), Decimal('42.0')),
        (Decimal('42.5'), Decimal('42.5')),
        (42.0, Err('Input should be an instance of Decimal [type=is_instance_of, input_value=42.0, input_type=float]')),
        ('42', Err("Input should be an instance of Decimal [type=is_instance_of, input_value='42', input_type=str]")),
        (42, Err('Input should be an instance of Decimal [type=is_instance_of, input_value=42, input_type=int]')),
        (True, Err('Input should be an instance of Decimal [type=is_instance_of, input_value=True, input_type=bool]')),
    ],
    ids=repr,
)
def test_decimal_strict_py(input_value, expected):
    v = SchemaValidator({'type': 'decimal', 'strict': True})
    if isinstance(expected, Err):
        with pytest.raises(ValidationError, match=re.escape(expected.message)):
            v.validate_python(input_value)
    else:
        output = v.validate_python(input_value)
        assert output == expected
        assert isinstance(output, Decimal)