A bug in Python 3.8 importlib.metadata requires a workaround

python/importlib_metadata#122 needs to be workedaround in 0.13

fixes pybuilder#807

src/integrationtest/python/issue_807_tests.py

@@ -0,0 +1,67 @@
+#   -*- coding: utf-8 -*-
+#
+#   This file is part of PyBuilder
+#
+#   Copyright 2011-2021 PyBuilder Team
+#
+#   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 sys
+import textwrap
+import unittest
+
+from itest_support import IntegrationTestSupport
+
+
+class Issue807Test(IntegrationTestSupport):
+    def test(self):
+        if sys.version_info[:2] < (3, 8):
+            # importlib.metadata does not exist before Python 3.8
+            return
+
+        self.write_build_file("""
+from pybuilder.core import use_plugin, init
+
+use_plugin("python.core")
+use_plugin("python.unittest")
+
+@init
+def init (project):
+    project.set_property("verbose", True)
+        """)
+
+        self.create_directory("src/main/python")
+        self.create_directory("src/unittest/python")
+        self.write_file("src/main/python/code.py", textwrap.dedent(
+            """
+            from importlib import metadata
+
+            def run_code():
+                return metadata.version("setuptools")
+            """))
+        self.write_file("src/unittest/python/code_tests.py", textwrap.dedent(
+            """
+            import unittest
+            import code
+
+            class CodeTests(unittest.TestCase):
+                def test_code(self):
+                    code.run_code()
+            """
+        ))
+        reactor = self.prepare_reactor()
+        reactor.build("verify")
+
+
+if __name__ == "__main__":
+    unittest.main()

src/main/python/pybuilder/extern/__init__.py

@@ -87,10 +87,17 @@ def load_module(self, fullname):
                 "distribution.".format(**locals())
             )
 
-    def find_distributions(self, context):
+    def _find_distributions(self, context):
         context.path.insert(0, pybuilder._vendor.__file__[:-len("__init__.py") - 1])
         return []
 
+    # https://github.com/pybuilder/pybuilder/issues/807
+    if sys.version_info[:2] == (3, 8):
+        def find_distributions(self, context):
+            return iter(self._find_distributions(context))
+    else:
+        find_distributions = _find_distributions
+
     def install(self):
         """
         Install this importer into sys.meta_path if not already present.