Add helper for decimal quantization, bump CyberSource REST client, qu…

…antize totals to 2 decimals
mitodl · Nov 8, 2024 · fa227d4 · fa227d4
1 parent a97420c
commit fa227d4
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Showing 6 changed files with 71 additions and 7 deletions.
diff --git a/src/payment_gateway/changelog.d/20241107_212223_jkachel_add_tax.md b/src/payment_gateway/changelog.d/20241107_212223_jkachel_add_tax.md
@@ -0,0 +1,43 @@
+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+-->
+
+<!--
+### Removed
+
+- A bullet item for the Removed category.
+
+-->
+
+### Added
+
+- Adds support for tax collection.
+- Bumps CyberSource REST Client package to at least 0.0.54.
+- Adds a helper for quantizing decimals for currency amounts.
+
+<!--
+### Changed
+
+- A bullet item for the Changed category.
+
+-->
+<!--
+### Deprecated
+
+- A bullet item for the Deprecated category.
+
+-->
+<!--
+### Fixed
+
+- A bullet item for the Fixed category.
+
+-->
+<!--
+### Security
+
+- A bullet item for the Security category.
+
+-->
diff --git a/src/payment_gateway/mitol/payment_gateway/api.py b/src/payment_gateway/mitol/payment_gateway/api.py
@@ -34,7 +34,7 @@
     InvalidTransactionException,
     RefundDuplicateException,
 )
-from mitol.payment_gateway.payment_utils import clean_request_data, strip_nones
+from mitol.payment_gateway.payment_utils import clean_request_data, strip_nones, quantize_decimal
 
 
 @dataclass
@@ -461,8 +461,8 @@ def prepare_checkout(
 
         payload = {
             "access_key": settings.MITOL_PAYMENT_GATEWAY_CYBERSOURCE_ACCESS_KEY,
-            "amount": str(total + tax_total),
-            "tax_amount": str(tax_total),
+            "amount": str(quantize_decimal((total + tax_total))),
+            "tax_amount": str(quantize_decimal((tax_total))),
             "consumer_id": consumer_id,
             "currency": "USD",
             "locale": "en-us",

diff --git a/src/payment_gateway/mitol/payment_gateway/payment_utils.py b/src/payment_gateway/mitol/payment_gateway/payment_utils.py
@@ -1,5 +1,7 @@
 """Utilities for the Payment Gateway"""
 
+from decimal import Decimal
+
 
 # To delete None values in Input Request Json body
 def clean_request_data(request_data):
@@ -21,3 +23,8 @@ def strip_nones(datasource):
             retval[key] = datasource[key]
 
     return retval
+
+
+def quantize_decimal(value, precision=2):
+    """Quantize a decimal value to the specified precision"""
+    return Decimal(value).quantize(Decimal("0.{}".format("0" * precision)))
diff --git a/src/payment_gateway/pyproject.toml b/src/payment_gateway/pyproject.toml
@@ -3,7 +3,7 @@ name = "mitol-django-payment-gateway"
 version = "2023.12.19"
 description = "Django application to handle payment processing"
 dependencies = [
-"cybersource-rest-client-python>=0.0.36",
+"cybersource-rest-client-python>=0.0.59",
 "django-stubs>=1.13.1",
 "django>=3.0",
 "mitol-django-common"

diff --git a/tests/mitol/payment_gateway/api/test_cybersource.py b/tests/mitol/payment_gateway/api/test_cybersource.py
@@ -5,6 +5,7 @@
 from collections import namedtuple
 from dataclasses import dataclass
 from datetime import datetime
+from decimal import Decimal
 from typing import Dict
 
 import pytest
@@ -98,8 +99,8 @@ def generate_test_cybersource_payload(order, cartitems, transaction_uuid):
 
     test_payload = {
         "access_key": settings.MITOL_PAYMENT_GATEWAY_CYBERSOURCE_ACCESS_KEY,
-        "amount": str(test_total + tax_total),
-        "tax_amount": str(tax_total),
+        "amount": str(Decimal(test_total + tax_total).quantize(Decimal("0.01"))),
+        "tax_amount": str(Decimal(tax_total).quantize(Decimal("0.01"))),
         "consumer_id": consumer_id,
         "currency": "USD",
         "locale": "en-us",

diff --git a/tests/mitol/payment_gateway/utils/test_payment_utils.py b/tests/mitol/payment_gateway/utils/test_payment_utils.py
@@ -1,7 +1,9 @@
 """Tests for payment_gateway application utils"""  # noqa: INP001
 
+from decimal import Decimal
+
 import pytest
-from mitol.payment_gateway.payment_utils import clean_request_data, strip_nones
+from mitol.payment_gateway.payment_utils import clean_request_data, strip_nones, quantize_decimal
 
 
 @pytest.mark.parametrize(
@@ -44,3 +46,14 @@ def test_strip_nones():
     test_ds2 = strip_nones(ds2)
 
     assert test_ds2 == ds2
+
+
+def test_quantize_decimal():
+    """Tests quantize_decimal to make sure that the decimal is quantized to the correct precision"""
+
+    test_decimal = 1.23456789
+    test_precision = 2
+
+    quantized_decimal = quantize_decimal(test_decimal, test_precision)
+
+    assert quantized_decimal == Decimal("1.23")