Don't evaluate descriptors or import __main__.py during docstring collection

Walk __dict__ like doctest.DocTestFinder instead of inspect.getmembers(),
which calls every descriptor's __get__, and skip __main__.py the way
pytest's doctest plugin does.

Fixes #76

Author: Bortlesboat

src/pytest_markdown_docs/plugin.py

@@ -357,7 +357,11 @@ def find_object_tests_recursive(
         _visited_objects.add(id(object))
         docstr = inspect.getdoc(object)
 
-        for member_name, member in inspect.getmembers(object):
+        # Walk __dict__ like doctest.DocTestFinder does, instead of
+        # inspect.getmembers(), so that descriptors are never evaluated.
+        for member in list(getattr(object, "__dict__", {}).values()):
+            if isinstance(member, (staticmethod, classmethod)):
+                member = member.__func__
             if (
                 inspect.isclass(member)
                 or inspect.isfunction(member)
@@ -436,6 +440,9 @@ def pytest_collect_file(
     if parent.config.option.markdowndocs:
         pathlib_path = pathlib.Path(str(file_path))  # pytest 7/8 compat
         if pathlib_path.suffix == ".py":
+            if pathlib_path.name == "__main__.py":
+                # importing it would clash with the running pytest's __main__
+                return None
             return MarkdownDocstringCodeModule.from_parent(parent, path=pathlib_path)
         elif pathlib_path.suffix in (".md", ".mdx", ".svx"):
             return MarkdownTextFile.from_parent(parent, path=pathlib_path)

tests/plugin_test.py

@@ -1,5 +1,7 @@
 import re
 
+import pytest
+
 from _pytest.pytester import LineMatcher
 
 import pytest_markdown_docs  # hack: used for storing a side effect in one of the tests
@@ -1109,3 +1111,51 @@ def test_top_level_await_requires_pytest_asyncio(testdir):
     result = testdir.runpytest("--markdown-docs")
     result.assert_outcomes(failed=1)
     result.stdout.fnmatch_lines(["*pytest-asyncio>=1.1.0*"])
+
+
+def test_docstring_collection_does_not_evaluate_descriptors(testdir):
+    testdir.makepyfile(
+        """
+        class Raising:
+            def __get__(self, instance, owner=None):
+                raise RuntimeError("evaluated during collection")
+
+
+        class Hostile:
+            attribute = Raising()
+
+            @staticmethod
+            def static():
+                \"\"\"
+                ```python
+                assert True
+                ```
+                \"\"\"
+
+            @classmethod
+            def klass(cls):
+                \"\"\"
+                ```python
+                assert True
+                ```
+                \"\"\"
+    """
+    )
+    result = testdir.runpytest("--markdown-docs")
+    result.assert_outcomes(passed=2)
+
+
+def test_main_py_is_skipped(testdir):
+    testdir.makepyfile(
+        __main__="""
+        def main():
+            \"\"\"
+            ```python
+            assert True
+            ```
+            \"\"\"
+        """
+    )
+    result = testdir.runpytest("--markdown-docs")
+    result.assert_outcomes()
+    assert result.ret == pytest.ExitCode.NO_TESTS_COLLECTED