Dynamically import hyperopt modules

freqtrade/optimize/__init__.py

@@ -1,9 +1,7 @@
 import logging
 from typing import Any, Dict
 
-from filelock import FileLock, Timeout
-
-from freqtrade import DependencyException, constants
+from freqtrade import DependencyException, constants, OperationalException
 from freqtrade.state import RunMode
 from freqtrade.utils import setup_utils_configuration
 
@@ -53,8 +51,12 @@ def start_hyperopt(args: Dict[str, Any]) -> None:
     :return: None
     """
     # Import here to avoid loading hyperopt module when it's not used
+    try:
+        from filelock import FileLock, Timeout
         from freqtrade.optimize.hyperopt import Hyperopt
-
+    except ImportError as e:
+        raise OperationalException(
+            f"{e}. Please ensure that the hyperopt dependencies are installed.") from e
     # Initialize configuration
     config = setup_configuration(args, RunMode.HYPEROPT)
 

tests/optimize/test_hyperopt.py

@@ -190,6 +190,37 @@ def test_hyperoptlossresolver_wrongname(mocker, default_conf, caplog) -> None:
         HyperOptLossResolver(default_conf, ).hyperopt
 
 
+def test_start_not_installed(mocker, default_conf, caplog) -> None:
+    start_mock = MagicMock()
+    patched_configuration_load_config_file(mocker, default_conf)
+    # Source of this test-method: https://stackoverflow.com/questions/2481511/mocking-importerror-in-python
+    import builtins
+    realimport = builtins.__import__
+
+    def mockedimport(name, *args, **kwargs):
+        if name == "filelock":
+            raise ImportError("No module named 'filelock'")
+        return realimport(name, *args, **kwargs)
+
+    builtins.__import__ = mockedimport
+
+    mocker.patch('freqtrade.optimize.hyperopt.Hyperopt.start', start_mock)
+    patch_exchange(mocker)
+
+    args = [
+        '--config', 'config.json',
+        'hyperopt',
+        '--epochs', '5'
+    ]
+    args = get_args(args)
+
+    with pytest.raises(OperationalException, match=r"Please ensure that the hyperopt dependencies"):
+        start_hyperopt(args)
+
+    # restore previous importfunction
+    builtins.__import__ = realimport
+
+
 def test_start(mocker, default_conf, caplog) -> None:
     start_mock = MagicMock()
     patched_configuration_load_config_file(mocker, default_conf)