Work around find_spec finding local subpackages (#2075)

### Changes
Fixed a bug with backend detection where NNCF would report every package
detected.

### Reason for changes
`importlib.utils.find_spec` turns out to find the local subpackages
instead of global packages if the global package is not present. Since
we have every backend as a local subpackage (e.g. at `nncf.torch`,
`nncf.tensorflow` etc.), the previous code would report every backend as
available, regardless of actual `torch` or `tensorflow` packages being
installed or not.

### Related tickets
N/A

### Tests
test_framework_detection

nncf/__init__.py

@@ -33,7 +33,13 @@
 
 from importlib.util import find_spec as _find_spec  # pylint:disable=wrong-import-position
 
-_AVAILABLE_FRAMEWORKS = {name: _find_spec(name) is not None for name in _SUPPORTED_FRAMEWORKS}
+_AVAILABLE_FRAMEWORKS = {}
+
+for fw_name in _SUPPORTED_FRAMEWORKS:
+    spec = _find_spec(fw_name)
+    # if the framework is not present, spec may still be not None because it found our nncf.*backend_name* subpackage
+    framework_present = spec is not None and spec.origin is not None and "nncf" not in spec.origin
+    _AVAILABLE_FRAMEWORKS[fw_name] = framework_present
 
 if not any(_AVAILABLE_FRAMEWORKS.values()):
     nncf_logger.error(

tests/common/conftest.py

@@ -0,0 +1,12 @@
+# Copyright (c) 2023 Intel Corporation
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#      http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from tests.shared.logging import nncf_caplog  # pylint:disable=unused-import

tests/common/test_framework_detection.py

@@ -0,0 +1,56 @@
+# Copyright (c) 2023 Intel Corporation
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#      http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import importlib
+import logging
+import re
+import unittest
+from importlib.machinery import ModuleSpec
+from typing import List
+from unittest.mock import MagicMock
+
+import pytest
+
+import nncf
+
+SUPPORTED_FRAMEWORKS = nncf._SUPPORTED_FRAMEWORKS  # pylint:disable=protected-access
+_REAL_FIND_SPEC = importlib._bootstrap._find_spec  # pylint:disable=protected-access
+
+
+class FailForModules:
+    def __init__(self, mocked_modules: List[str], hidden_modules: List[str]):
+        self._mocked_modules = mocked_modules
+        self._hidden_modules = hidden_modules
+
+    def __call__(self, fullname, path=None, target=None):
+        if fullname in self._hidden_modules:
+            return None
+        if fullname in self._mocked_modules:
+            return ModuleSpec(fullname, loader=MagicMock(), origin="foo/bar")
+        return _REAL_FIND_SPEC(fullname, path, target)
+
+
+@pytest.mark.parametrize("ref_available_frameworks", [["torch"], ["torch", "tensorflow"], ["onnx", "openvino"], []])
+def test_frameworks_detected(ref_available_frameworks: List[str], nncf_caplog, mocker):
+    unavailable_frameworks = [fw for fw in SUPPORTED_FRAMEWORKS if fw not in ref_available_frameworks]
+    failer = FailForModules(ref_available_frameworks, unavailable_frameworks)
+    with unittest.mock.patch("importlib.util.find_spec", wraps=failer):
+        with nncf_caplog.at_level(logging.INFO):
+            importlib.reload(nncf)
+            matches = re.search(r"Supported frameworks detected: (.*)", nncf_caplog.text)
+            if ref_available_frameworks:
+                assert matches is not None
+                match_text = matches[0]
+                for fw in ref_available_frameworks:
+                    assert fw in match_text
+                for fw in unavailable_frameworks:
+                    assert fw not in match_text
+            else:
+                assert matches is None