Added support for astroid ≥ 2.6.0 (#38)

The code in astroid underwent a minor refactoring and broke the public
interface (`ALL_NODE_CLASSES` were moved to `astroid.nodes` module).
This had repercussions on pyicontract-lint since an assertion depends on
it.

This patch examines the version of astroid and adapts the assertion
according to the version so that both older and newer versions of
astroid are supported.

Fixes #37.

icontract_lint/__init__.py

@@ -7,7 +7,7 @@
 import re
 import sys
 import traceback
-from typing import Set, List, Mapping, Optional, TextIO, Any
+from typing import Set, List, Mapping, Optional, TextIO, Any, Tuple
 
 import astroid
 import astroid.modutils
@@ -26,6 +26,13 @@
 __license__ = pyicontract_lint_meta.__license__
 __copyright__ = pyicontract_lint_meta.__copyright__
 
+# noinspection PyBroadException
+try:
+    _ASTROID_VERSION_TUPLE = tuple(
+        int(part) for part in re.split('.', astroid.__version__))  # type: Optional[Tuple[int, ...]]
+except Exception:  # pylint: disable=broad-except
+    _ASTROID_VERSION_TUPLE = None
+
 
 class ErrorID(enum.Enum):
     """Enumerate error identifiers."""
@@ -101,7 +108,17 @@ class _AstroidVisitor:
     If the visit function has not been defined, ``visit_generic`` is invoked.
     """
 
-    assert "generic" not in [cls.__class__.__name__ for cls in astroid.ALL_NODE_CLASSES]
+    if _ASTROID_VERSION_TUPLE is not None and _ASTROID_VERSION_TUPLE < (2, 6, 0):
+        _ALL_NODE_CLASSES = [cls.__class__.__name__ for cls in astroid.ALL_NODE_CLASSES]
+    else:
+        _ALL_NODE_CLASSES = [cls.__class__.__name__ for cls in astroid.nodes.ALL_NODE_CLASSES]
+
+    assert "generic" not in _ALL_NODE_CLASSES, \
+        (
+            "We need ``generic`` as reserved name for the visitor (``visit_generic``). "
+            "However, if there is a class in the astroid with the same name, it would break the visitor. "
+            "(The version of astroid is: {}.)".format(astroid.__version__)
+        )
 
     def visit(self, node: astroid.node_classes.NodeNG):
         """Enter the visitor."""

setup.py

@@ -40,7 +40,12 @@
     license='License :: OSI Approved :: MIT License',
     keywords='design-by-contract precondition postcondition validation lint',
     packages=find_packages(exclude=['tests']),
-    install_requires=['icontract>=2.0.0,<3', 'astroid>=2.4.2,<3'],
+    install_requires=[
+        # yapf: disable
+        'icontract>=2.0.0,<3',
+        'astroid>=2.4.2,<3'
+        # yapf: enable
+    ],
     extras_require={
         'dev': [
             # yapf: disable