Add iterable tests

tests/snippets/iterable.py

@@ -0,0 +1,32 @@
+from testutils import assert_raises
+
+def test_container(x):
+    assert 3 in x
+    assert 4 not in x
+    assert list(x) == list(iter(x))
+    assert list(x) == [0, 1, 2, 3]
+    assert [*x] == [0, 1, 2, 3]
+    lst = []
+    lst.extend(x)
+    assert lst == [0, 1, 2, 3]
+
+class C:
+    def __iter__(self):
+        return iter([0, 1, 2, 3])
+test_container(C())
+
+class C:
+    def __getitem__(self, x):
+        return (0, 1, 2, 3)[x] # raises IndexError on x==4
+test_container(C())
+
+class C:
+    def __getitem__(self, x):
+        if x > 3:
+            raise StopIteration
+        return x
+test_container(C())
+
+class C: pass
+assert_raises(TypeError, lambda: 5 in C())
+assert_raises(TypeError, lambda: iter(C))