Add a "table_from()" test that tries arbitrary data structures.

We do not currently translate them transitively, but we might do that in the future.

lupa/tests/__init__.py

@@ -15,6 +15,14 @@ class LupaTestCase(unittest.TestCase):
     """
     lupa = lupa
 
+    if sys.version_info < (3, 4):
+        from contextlib import contextmanager
+
+        @contextmanager
+        def subTest(self, message=None, **parameters):
+            """Dummy implementation"""
+            yield
+
 
 def find_lua_modules():
     modules = [lupa]

lupa/tests/test.py

@@ -598,6 +598,23 @@ def test_table_from_bad(self):
         self.assertRaises(TypeError, self.lua.table_from, None)
         self.assertRaises(TypeError, self.lua.table_from, {"a": 5}, 123)
 
+    def test_table_from_nested_datastructures(self):
+        from itertools import count
+        def make_ds(*children):
+            yield list(children)
+            yield dict(zip(count(), children))
+            yield {chr(ord('A') + i): child for i, child in enumerate(children)}
+
+        elements = [1, 2, 'x', 'y']
+        for ds1 in make_ds(*elements):
+            for ds2 in make_ds(ds1):
+                for ds3 in make_ds(ds1, elements, ds2):
+                    for ds in make_ds(ds1, ds2, ds3):
+                        with self.subTest(ds=ds):
+                            table = self.lua.table_from(ds)
+                            # we don't translate transitively, so apply arbitrary test operation
+                            self.assertTrue(list(table))
+
     # def test_table_from_nested(self):
     #     table = self.lua.table_from({"obj": {"foo": "bar"}})
     #     lua_type = self.lua.eval("type")