Improve code quality

tests/data/test_btanalysis.py

@@ -98,7 +98,7 @@ def test_load_backtest_data_new_format(testdatadir):
     assert bt_data.equals(bt_data3)
 
     with pytest.raises(ValueError, match=r"File .* does not exist\."):
-        load_backtest_data(str("filename") + "nofile")
+        load_backtest_data("filename" + "nofile")
 
     with pytest.raises(ValueError, match=r"Unknown dataformat."):
         load_backtest_data(testdatadir / "backtest_results" / LAST_BT_RESULT_FN)

tests/data/test_history.py

@@ -409,7 +409,7 @@ def test_init_with_refresh(default_conf, mocker) -> None:
 
 
 def test_file_dump_json_tofile(testdatadir) -> None:
-    file = testdatadir / 'test_{id}.json'.format(id=str(uuid.uuid4()))
+    file = testdatadir / f'test_{uuid.uuid4()}.json'
     data = {'bar': 'foo'}
 
     # check the file we will create does not exist