Use tensorboard fallback for mac tests

tests/freqai/test_freqai_interface.py

@@ -42,6 +42,30 @@ def can_run_model(model: str) -> None:
         pytest.skip("Reinforcement learning / PyTorch module not available on intel based Mac OS.")
 
 
+@pytest.fixture(scope="function")
+def import_fails_mac() -> None:
+    # Source of this test-method:
+    # https://stackoverflow.com/questions/2481511/mocking-importerror-in-python
+    if is_mac():
+        import builtins
+        realimport = builtins.__import__
+
+        def mockedimport(name, *args, **kwargs):
+            if name in ["freqtrade.freqai.tensorboard.tensorboard"]:
+                raise ImportError(f"No module named '{name}'")
+            return realimport(name, *args, **kwargs)
+
+        builtins.__import__ = mockedimport
+
+        # Run test - then cleanup
+        yield
+
+        # restore previous importfunction
+        builtins.__import__ = realimport
+    else:
+        yield
+
+
 @pytest.mark.parametrize('model, pca, dbscan, float32, can_short, shuffle, buffer', [
     ('LightGBMRegressor', True, False, True, True, False, 0),
     ('XGBoostRegressor', False, True, False, True, False, 10),
@@ -55,7 +79,7 @@ def can_run_model(model: str) -> None:
     ('ReinforcementLearner_test_3ac', False, False, False, True, False, 0),
     ('ReinforcementLearner_test_4ac', False, False, False, True, False, 0),
     ])
-def test_extract_data_and_train_model_Standard(mocker, freqai_conf, model, pca,
+def test_extract_data_and_train_model_Standard(mocker, freqai_conf, model, pca, import_fails_mac,
                                                dbscan, float32, can_short, shuffle, buffer):
 
     can_run_model(model)