test: add test for fetch_funding_rate

part of #12206

tests/exchange/test_exchange.py

@@ -6319,3 +6319,39 @@ def test_exchange_features(default_conf, mocker):
     assert exchange.features("futures", "fetchOHLCV", "limit", 500) == 997
     # Fall back to default
     assert exchange.features("futures", "fetchOHLCV_else", "limit", 601) == 601
+
+
+@pytest.mark.parametrize("exchange_name", EXCHANGES)
+def test_fetch_funding_rate(default_conf, mocker, exchange_name):
+    api_mock = MagicMock()
+    funding_rate = {
+        "symbol": "ETH/BTC",
+        "fundingRate": 5.652e-05,
+        "fundingTimestamp": 1757174400000,
+        "fundingDatetime": "2025-09-06T16:00:00.000Z",
+    }
+    api_mock.fetch_funding_rate = MagicMock(return_value=funding_rate)
+    api_mock.markets = {"ETH/BTC": {"active": True}}
+    exchange = get_patched_exchange(mocker, default_conf, api_mock, exchange=exchange_name)
+    # retrieve original funding rate
+    funding_rate = exchange.fetch_funding_rate(pair="ETH/BTC")
+    assert funding_rate["fundingRate"] == funding_rate["fundingRate"]
+    assert funding_rate["fundingTimestamp"] == funding_rate["fundingTimestamp"]
+    assert funding_rate["fundingDatetime"] == funding_rate["fundingDatetime"]
+
+    ccxt_exceptionhandlers(
+        mocker,
+        default_conf,
+        api_mock,
+        exchange_name,
+        "fetch_funding_rate",
+        "fetch_funding_rate",
+        pair="ETH/BTC",
+    )
+
+    api_mock.fetch_funding_rate = MagicMock(return_value={})
+    exchange = get_patched_exchange(mocker, default_conf, api_mock, exchange=exchange_name)
+    exchange.fetch_funding_rate(pair="ETH/BTC")
+
+    with pytest.raises(DependencyException, match=r"Pair XRP/ETH not available"):
+        exchange.fetch_funding_rate(pair="XRP/ETH")