Add test for unicode responses from API, and fix the bug that trigger…

…s it.

See for details:
- psf/requests#1604
- https://github.com/requests/requests/blob/9cfd292da33f3b8324ce2c20e01db0e2f8b9210b/requests/utils.py#L473

mollie/api/resources/base.py

@@ -72,6 +72,8 @@ def list(self, **params):
 
     def perform_api_call(self, http_method, path, data=None, params=None):
         resp = self.client.perform_http_call(http_method, path, data, params)
+        # Mollie returns unicode data in responses, but doesn't set the Content-Type header correctly
+        resp.encoding = 'utf-8'
         try:
             result = resp.json() if resp.status_code != 204 else {}
         except Exception:

tests/responses/order_error.json

@@ -0,0 +1,12 @@
+{
+  "status": 422,
+  "title": "Unprocessable Entity",
+  "detail": "Order line 1 is invalid. VAT amount is off. Expected VAT amount to be €3.47 (21.00% over €20.00), got €3.10",
+  "field": "lines.1.vatAmount",
+  "_links": {
+    "documentation": {
+      "href": "https://docs.mollie.com/guides/handling-errors",
+      "type": "text/html"
+    }
+  }
+}

tests/test_client.py

@@ -207,3 +207,16 @@ def test_client_error_including_field_response(client, response):
         client.payments.create(**params)
     assert excinfo.match('The amount is higher than the maximum')
     assert excinfo.value.field == 'amount'
+
+
+def test_client_unicode_error(client, response):
+    """An error response containing Unicode characters should also be processed correctly."""
+    response.post('https://api.mollie.com/v2/orders', 'order_error', status=422)
+    with pytest.raises(UnprocessableEntityError) as err:
+        # actual POST data for creating an order can be found in test_orders.py
+        client.orders.create({})
+
+    # printing the result should work even when utf-8 characters are in the response.
+    expected = "UnprocessableEntityError('Order line 1 is invalid. VAT amount is off. Expected VAT amount " \
+               "to be €3.47 (21.00% over €20.00), got €3.10',)"
+    assert repr(err.value) == expected