Merge pull request #12 from k0t3n/feature/min-max-amounts

Feature/min max amounts

changelly_api/api.py

@@ -5,17 +5,18 @@
 
 import requests
 
+from changelly_api.conf import *
 from changelly_api.exceptions import *
 
 
 class ChangellyAPI:
-    def __init__(self, api_key, secret, url='https://api.changelly.com'):
+    def __init__(self, api_key, api_secret, url=API_ROOT_URL):
         self._api_key = api_key
-        self._secret = secret
+        self._api_secret = api_secret
         self._url = url
 
     def _generate_sign(self, json_data):
-        return hmac.new(self._secret.encode('utf-8'), json_data.encode('utf-8'), hashlib.sha512).hexdigest()
+        return hmac.new(self._api_secret.encode('utf-8'), json_data.encode('utf-8'), hashlib.sha512).hexdigest()
 
     def _parse_response(self, response):
         if response.status_code == 401:
@@ -30,6 +31,15 @@ def _parse_response(self, response):
             raise JSONResponseParseError('Error parsing JSON response')
 
         if data.get('error'):
+
+            if data['error']['code'] == INVALID_AMOUNT_ERROR_CODE:
+                value = float(data['error']['message'][34:36])
+
+                if 'maximal' in data['error']['message']:
+                    raise AmountGreaterThanMaximum(value)
+                elif 'minimal' in data['error']['message']:
+                    raise AmountLessThanMinimum(value)
+
             raise ChangellyAPIError(data['error'])
 
         return data.get('result')
@@ -44,10 +54,12 @@ def _make_request(self, method, params=None):
 
         serialized_data = json.dumps(message)
 
-        sign = hmac.new(self._secret.encode('utf-8'), serialized_data.encode('utf-8'), hashlib.sha512).hexdigest()
-
-        headers = {'api-key': self._api_key, 'sign': sign, 'Content-type': 'application/json'}
-        response = requests.post(self._url, headers=headers, data=serialized_data)
+        headers = {'api-key': self._api_key, 'sign': self._generate_sign(serialized_data),
+                   'Content-type': 'application/json'}
+        try:
+            response = requests.post(self._url, headers=headers, data=serialized_data)
+        except requests.RequestException as error:
+            raise ChangellyAPIError(f'Unknown error occurred during request: {error}')
 
         return self._parse_response(response)
 

changelly_api/conf.py

@@ -0,0 +1,3 @@
+API_ROOT_URL = 'https://api.changelly.com'
+
+INVALID_AMOUNT_ERROR_CODE = -32600

changelly_api/exceptions.py

@@ -2,6 +2,19 @@ class ChangellyAPIError(Exception):
     pass
 
 
+class InvalidAmount(ChangellyAPIError):
+    def __init__(self, threshold_value: float):
+        self.threshold_value = threshold_value
+
+
+class AmountGreaterThanMaximum(InvalidAmount):
+    pass
+
+
+class AmountLessThanMinimum(InvalidAmount):
+    pass
+
+
 class JSONResponseParseError(ChangellyAPIError):
     pass
 

tests/conftest.py

@@ -0,0 +1,31 @@
+import pytest
+
+from changelly_api import ChangellyAPI
+
+
+@pytest.fixture(scope='module')
+def api():
+    return ChangellyAPI('key', 'secret')
+
+
+@pytest.fixture()
+def get_fix_rate_for_amount_data():
+    return {
+        'response': {
+            "jsonrpc": "2.0",
+            "id": 1,
+            "result": {
+                "id": "test",
+                "from": "btc",
+                "to": "eth",
+                "result": "48.520938768637152700759353642",
+                "amountFrom": "1",
+                "amountTo": "48.520938768637152700"
+            }
+        },
+        'request': {
+            'from': 'btc',
+            'to': 'eth',
+            'amountFrom': 1,
+        }
+    }

tests/generate_sign_test.py

@@ -1,14 +1,5 @@
 import json
 
-import pytest
-
-from changelly_api import ChangellyAPI
-
-
-@pytest.fixture(scope='module')
-def api():
-    return ChangellyAPI('key', 'secret')
-
 
 def test_generate_sign(api):
     data = {

tests/get_fix_rate_for_amount_test.py

@@ -0,0 +1,50 @@
+import pytest
+import requests_mock
+
+from changelly_api.conf import API_ROOT_URL
+from changelly_api.exceptions import AmountGreaterThanMaximum, AmountLessThanMinimum
+
+
+@requests_mock.Mocker(kw='requests_mock')
+def test(api, get_fix_rate_for_amount_data, **kwargs):
+    r_mock = kwargs['requests_mock']
+    r_mock.post(API_ROOT_URL, json=get_fix_rate_for_amount_data['response'])
+    response = api.get_fix_rate_for_amount(get_fix_rate_for_amount_data['request'])
+
+    assert response == get_fix_rate_for_amount_data['response']['result']
+
+
+@requests_mock.Mocker(kw='requests_mock')
+def test_invalid_minimum_amount(api, get_fix_rate_for_amount_data, **kwargs):
+    minimum_amount = 10
+    r_mock = kwargs['requests_mock']
+    data = {
+        'error': {
+            'code': -32600,
+            'message': f'invalid amount: minimal amount is {minimum_amount}'
+        }
+    }
+    r_mock.post(API_ROOT_URL, json=data)
+
+    with pytest.raises(AmountLessThanMinimum) as error:
+        api.get_fix_rate_for_amount(get_fix_rate_for_amount_data['request'])
+
+    assert error.value.threshold_value == minimum_amount
+
+
+@requests_mock.Mocker(kw='requests_mock')
+def test_invalid_maximum_amount(api, get_fix_rate_for_amount_data, **kwargs):
+    maximum_amount = 10
+    r_mock = kwargs['requests_mock']
+    response = {
+        'error': {
+            'code': -32600,
+            'message': f'invalid amount: maximal amount is {maximum_amount}'
+        }
+    }
+    r_mock.post(API_ROOT_URL, json=response)
+
+    with pytest.raises(AmountGreaterThanMaximum) as error:
+        api.get_fix_rate_for_amount(get_fix_rate_for_amount_data['request'])
+
+    assert error.value.threshold_value == maximum_amount

tests/requirements.txt

@@ -1,3 +1,5 @@
 pytest-cov
 codecov
-pytest
+pytest
+mock
+requests_mock