1 files changed, 75 insertions, 0 deletions
diff --git a/tests/test_runtime.py b/tests/test_runtime.py
new file mode 100644
index 0000000..1978c64
--- /dev/null
+++ b/tests/test_runtime.py
@@ -0,0 +1,75 @@
+import itertools
+
+from jinja2 import Template
+from jinja2.runtime import LoopContext
+
+TEST_IDX_TEMPLATE_STR_1 = (
+    "[{% for i in lst|reverse %}(len={{ loop.length }},"
+    " revindex={{ loop.revindex }}, index={{ loop.index }}, val={{ i }}){% endfor %}]"
+)
+TEST_IDX0_TEMPLATE_STR_1 = (
+    "[{% for i in lst|reverse %}(len={{ loop.length }},"
+    " revindex0={{ loop.revindex0 }}, index0={{ loop.index0 }}, val={{ i }})"
+    "{% endfor %}]"
+)
+
+
+def test_loop_idx():
+    t = Template(TEST_IDX_TEMPLATE_STR_1)
+    lst = [10]
+    excepted_render = "[(len=1, revindex=1, index=1, val=10)]"
+    assert excepted_render == t.render(lst=lst)
+
+
+def test_loop_idx0():
+    t = Template(TEST_IDX0_TEMPLATE_STR_1)
+    lst = [10]
+    excepted_render = "[(len=1, revindex0=0, index0=0, val=10)]"
+    assert excepted_render == t.render(lst=lst)
+
+
+def test_loopcontext0():
+    in_lst = []
+    lc = LoopContext(reversed(in_lst), None)
+    assert lc.length == len(in_lst)
+
+
+def test_loopcontext1():
+    in_lst = [10]
+    lc = LoopContext(reversed(in_lst), None)
+    assert lc.length == len(in_lst)
+
+
+def test_loopcontext2():
+    in_lst = [10, 11]
+    lc = LoopContext(reversed(in_lst), None)
+    assert lc.length == len(in_lst)
+
+
+def test_iterator_not_advanced_early():
+    t = Template("{% for _, g in gs %}{{ loop.index }} {{ g|list }}\n{% endfor %}")
+    out = t.render(
+        gs=itertools.groupby([(1, "a"), (1, "b"), (2, "c"), (3, "d")], lambda x: x[0])
+    )
+    # groupby groups depend on the current position of the iterator. If
+    # it was advanced early, the lists would appear empty.
+    assert out == "1 [(1, 'a'), (1, 'b')]\n2 [(2, 'c')]\n3 [(3, 'd')]\n"
+
+
+def test_mock_not_pass_arg_marker():
+    """If a callable class has a ``__getattr__`` that returns True-like
+    values for arbitrary attrs, it should not be incorrectly identified
+    as a ``pass_context`` function.
+    """
+
+    class Calc:
+        def __getattr__(self, item):
+            return object()
+
+        def __call__(self, *args, **kwargs):
+            return len(args) + len(kwargs)
+
+    t = Template("{{ calc() }}")
+    out = t.render(calc=Calc())
+    # Would be "1" if context argument was passed.
+    assert out == "0"