Add legacy bytecode compatibility tests

ncoghlan · Mar 8, 2017 · Feb 19, 2017 · Feb 24, 2017 · Feb 24, 2017 · Feb 24, 2017
commit ca248646d497d06580d02dcc43d9607d4e2f1dfd
diff --git a/Lib/test/test_importlib/source/test_file_loader.py b/Lib/test/test_importlib/source/test_file_loader.py
@@ -603,5 +603,109 @@ class SourcelessLoaderBadBytecodeTestPEP302(SourcelessLoaderBadBytecodeTest,
                     util=importlib_util)
 
 
+###########################################################################
+# Issue #29537: Test backwards compatibility with legacy 3.5.0/1/2 bytecode
+###########################################################################
+
+class LegacyBytecodeTest:
+
+    def _test_legacy_magic(self, test, *, del_source=False):
+        # Replace the default magic number with one copied from a pyc file
+        # generated by Python 3.5.2
+        with util.create_modules('_temp') as mapping:
+            bc_path = self.manipulate_bytecode('_temp', mapping,
+                                    lambda bc: b'\x16\r\r\n' + bc[4:])
+            test('_temp', mapping, bc_path)
+
+LegacyBytecodeTestPEP451 = BadBytecodeTestPEP451
+LegacyBytecodeTestPEP302 = BadBytecodeTestPEP302
+
+# SourceLoader via both PEP 451 and 302 hooks
+
+class SourceLoaderLegacyBytecodeTest(LegacyBytecodeTest):
+
+    @classmethod
+    def setUpClass(cls):
+        cls.loader = cls.machinery.SourceFileLoader
+
+    @util.writes_bytecode_files
+    def test_legacy_magic(self):
+        # The magic number from 3.5.0/1/2 should be accepted as is
+        def test(name, mapping, bytecode_path):
+            self.import_(mapping[name], name)
+            with open(bytecode_path, 'rb') as bytecode_file:
+                self.assertEqual(bytecode_file.read(4),
+                                 self.util._BACKCOMPAT_MAGIC_NUMBER)
+
+        self._test_legacy_magic(test)
+
+
+class SourceLoaderLegacyBytecodeTestPEP451(
+        SourceLoaderLegacyBytecodeTest, LegacyBytecodeTestPEP451):
+    pass
+
+
+(Frozen_SourceLegacyBytecodePEP451,
+ Source_SourceLegacyBytecodePEP451
+ ) = util.test_both(SourceLoaderLegacyBytecodeTestPEP451, importlib=importlib,
+                    machinery=machinery, abc=importlib_abc,
+                    util=importlib_util)
+
+
+class SourceLoaderLegacyBytecodeTestPEP302(
+        SourceLoaderLegacyBytecodeTest, LegacyBytecodeTestPEP302):
+    pass
+
+
+(Frozen_SourceLegacyBytecodePEP302,
+ Source_SourceLegacyBytecodePEP302
+ ) = util.test_both(SourceLoaderLegacyBytecodeTestPEP302, importlib=importlib,
+                    machinery=machinery, abc=importlib_abc,
+                    util=importlib_util)
+
+# SourcelessLoader via both PEP 451 and 302 hooks
+
+class SourcelessLoaderLegacyBytecodeTest(LegacyBytecodeTest):
+
+    @classmethod
+    def setUpClass(cls):
+        cls.loader = cls.machinery.SourcelessFileLoader
+
+
+    @util.writes_bytecode_files
+    def test_legacy_magic(self):
+        # The magic number from 3.5.0/1/2 should be accepted as is
+        def test(name, mapping, bytecode_path):
+            self.import_(bytecode_path, name)
+            with open(bytecode_path, 'rb') as bytecode_file:
+                self.assertEqual(bytecode_file.read(4),
+                                 self.util._BACKCOMPAT_MAGIC_NUMBER)
+
+        self._test_legacy_magic(test)
+
+class SourcelessLoaderLegacyBytecodeTestPEP451(
+        SourcelessLoaderLegacyBytecodeTest, LegacyBytecodeTestPEP451):
+    pass
+
+(Frozen_SourcelessLegacyBytecodePEP451,
+ Source_SourcelessLegacyBytecodePEP451
+ ) = util.test_both(SourcelessLoaderLegacyBytecodeTestPEP451, importlib=importlib,
+                    machinery=machinery, abc=importlib_abc,
+                    util=importlib_util)
+
+
+class SourcelessLoaderLegacyBytecodeTestPEP302(SourcelessLoaderLegacyBytecodeTest,
+        LegacyBytecodeTestPEP302):
+    pass
+
+
+(Frozen_SourcelessLegacyBytecodePEP302,
+ Source_SourcelessLegacyBytecodePEP302
+ ) = util.test_both(SourcelessLoaderLegacyBytecodeTestPEP302, importlib=importlib,
+                    machinery=machinery, abc=importlib_abc,
+                    util=importlib_util)
+
+# End of Issue #29537 legacy bytecode compatibility tests
+
 if __name__ == '__main__':
     unittest.main()