From 54fd0cd97c855b212a52857c878f3a6d4c3d052b Mon Sep 17 00:00:00 2001
From: Alex the wizard <sashok1111122222@gmail.com>
Date: Tue, 13 Aug 2024 16:12:40 +0300
Subject: [PATCH] feat: create get_exchange_rate() method and tests for it

---
 cashctrl_api/client.py   | 26 ++++++++++++++++++++++++++
 tests/test_currencies.py | 21 +++++++++++++++++++++
 2 files changed, 47 insertions(+)
 create mode 100644 tests/test_currencies.py

diff --git a/cashctrl_api/client.py b/cashctrl_api/client.py
index 11cf4a8..dd9e8b6 100644
--- a/cashctrl_api/client.py
+++ b/cashctrl_api/client.py
@@ -1,5 +1,6 @@
 """Module to interact with the REST API of the CashCtrl accounting service."""
 
+from datetime import datetime
 import json
 from mimetypes import guess_type
 import os
@@ -557,3 +558,28 @@ def list_journal_entries(self) -> pd.DataFrame:
         journal_entries = pd.DataFrame(response["data"])
         df = enforce_dtypes(journal_entries, JOURNAL_ENTRIES)
         return df.sort_values("dateAdded")
+
+    # ----------------------------------------------------------------------
+    # Price
+
+    def get_exchange_rate(
+        self,
+        from_currency: str,
+        to_currency: str,
+        date: datetime.date = None
+    ) -> float:
+        """
+        Retrieves the exchange rate for a given currency pair on a specific date.
+
+        Args:
+            from_currency (str): The currency code to convert from.
+            to_currency (str): The currency code to convert to.
+            date (datetime.date, optional): The date for which the exchange rate
+                is requested. Defaults to None, which retrieves the latest rate.
+
+        Returns:
+            float: The exchange rate for the given currency pair.
+        """
+        params = {"from": from_currency, "to": to_currency, "date": date}
+        response = self.request("GET", "currency/exchangerate", params=params)
+        return response.json()
diff --git a/tests/test_currencies.py b/tests/test_currencies.py
new file mode 100644
index 0000000..dc999e6
--- /dev/null
+++ b/tests/test_currencies.py
@@ -0,0 +1,21 @@
+"""Unit tests for currencies."""
+
+from cashctrl_api import CashCtrlClient
+import pytest
+
+
+def test_exchange_rate():
+    cc_client = CashCtrlClient()
+
+    exchange_rate = cc_client.get_exchange_rate("USD", "CHF")
+    assert isinstance(exchange_rate, float), "`exchange_rate` is not a Float."
+
+    # Exchange rate for invalid currency should raise an error
+    with pytest.raises(Exception):
+        cc_client.get_exchange_rate("USD", "INVALID")
+
+    exchange_rate = cc_client.get_exchange_rate("USD", "USD")
+    assert exchange_rate == 1, "Exchange rate for the same currency should be 1."
+
+    exchange_rate = cc_client.get_exchange_rate("USD", "CHF", '2020-01-15')
+    assert exchange_rate == 0.967145, "Exchange rate for USD-CHF on 2020-01-15 should be 0.967145."