Add tests for currency clean amount

tests/test_currencies.py

@@ -0,0 +1,58 @@
+from decimal import Decimal
+
+import pytest
+from pycountries.currencies import (
+    AmountSpecialValuesNotAllowedError,
+    Currency,
+    NegativeAmountNotAllowedError,
+    WrongAmountDigitsNumberError,
+    WrongAmountTypeError,
+    ZeroAmountNotAllowedError,
+)
+
+
+class TestCurrencyCleanAmount:
+    two_digits_currency = Currency.two_digits[0]
+
+    def test_clean_amount_should_raise_amount_special_values_not_allowed_error_when_currency_has_two_digits_and_amount_is_inf_decimal(  # noqa: E501
+        self,
+    ):
+        amount: Decimal = Decimal("inf")
+        with pytest.raises(AmountSpecialValuesNotAllowedError):
+            self.two_digits_currency.clean_amount(amount)
+
+    def test_clean_amount_should_raise_negative_amount_not_allowed_error_when_currency_has_two_digits_and_amount_is_negative_decimal(  # noqa: E501
+        self,
+    ):
+        amount: Decimal = Decimal("-20")
+        with pytest.raises(NegativeAmountNotAllowedError):
+            self.two_digits_currency.clean_amount(amount)
+
+    def test_clean_amount_should_raise_wrong_amount_digits_number_error_when_currency_has_two_digits_and_amount_is_decimal_and_has_three_digits(  # noqa: E501
+        self,
+    ):
+        amount: Decimal = Decimal("1.234")
+        with pytest.raises(WrongAmountDigitsNumberError):
+            self.two_digits_currency.clean_amount(amount)
+
+    def test_clean_amount_should_raise_wrong_amount_type_error_when_currency_has_two_digits_and_amount_is_int(self):
+        amount: int = 1
+        with pytest.raises(WrongAmountTypeError):
+            self.two_digits_currency.clean_amount(amount)
+
+    def test_clean_amount_should_raise_zero_amount_not_allowed_error_when_amount_is_zero_decimal_and_allow_zero_is_false(  # noqa: E501
+        self,
+    ):
+        amount: Decimal = Decimal("0")
+        with pytest.raises(ZeroAmountNotAllowedError):
+            self.two_digits_currency.clean_amount(amount, allow_zero=False)
+
+    def test_clean_amount_should_return_zero_decimal_when_amount_is_zero_decimal_and_allow_zero_is_true(self):
+        amount: Decimal = Decimal("0")
+        assert self.two_digits_currency.clean_amount(amount) == amount
+
+    def test_clean_amount_should_return_fixed_digest_decimal_when_currency_has_two_digits_and_amount_has_missing_digits(
+        self,
+    ):
+        amount: Decimal = Decimal("20.2")
+        assert str(self.two_digits_currency.clean_amount(amount)) == str(Decimal("20.20"))