Bug fix 794 Fix of loop index, revidex and length issues

jinja2/runtime.py

@@ -422,29 +422,17 @@ class LoopContext(LoopContextBase):
 
     def __init__(self, iterable, undefined, recurse=None, depth0=0):
         LoopContextBase.__init__(self, undefined, recurse, depth0)
-        self._iterator = iter(iterable)
-
-        # try to get the length of the iterable early.  This must be done
-        # here because there are some broken iterators around where there
-        # __len__ is the number of iterations left (i'm looking at your
-        # listreverseiterator!).
         try:
+            # Getting length of iterable
+            iterable = tuple(iterable)
             self._length = len(iterable)
+            self._iterator = iter(iterable)
         except (TypeError, AttributeError):
             self._length = None
         self._after = self._safe_next()
 
     @property
     def length(self):
-        if self._length is None:
-            # if was not possible to get the length of the iterator when
-            # the loop context was created (ie: iterating over a generator)
-            # we have to convert the iterable into a sequence and use the
-            # length of that + the number of iterations so far.
-            iterable = tuple(self._iterator)
-            self._iterator = iter(iterable)
-            iterations_done = self.index0 + 2
-            self._length = len(iterable) + iterations_done
         return self._length
 
     def __iter__(self):

tests/test_filters.py

@@ -135,6 +135,12 @@ def test_format(self, env):
         out = tmpl.render()
         assert out == 'a|b'
 
+    def test_to_format_exception(self):
+        from jinja2.filters import do_format
+        from jinja2.exceptions import FilterArgumentError
+        with pytest.raises(FilterArgumentError):
+            do_format('value', 'values', key='key', keys='keys')
+
     def test_indent(self, env):
         text = '\n'.join(['', 'foo bar', ''])
         t = env.from_string('{{ foo|indent(2, false, false) }}')
@@ -228,6 +234,44 @@ def test_reverse(self, env):
                                '{{ [1, 2, 3]|reverse|list }}')
         assert tmpl.render() == 'raboof|[3, 2, 1]'
 
+    def test_reverse_non_iterable(self):
+        from jinja2.filters import do_reverse
+        from jinja2.exceptions import FilterArgumentError
+
+        non_iterable = 42
+        with pytest.raises(FilterArgumentError):
+            do_reverse(value=non_iterable)
+
+    def test_reverse_iterable(self):
+        from jinja2.filters import do_reverse
+
+        lst = [1, 66, 55]
+        assert list(do_reverse(value=lst)) == lst[::-1]
+
+        string_value = 'abc'
+        assert list(do_reverse(value=string_value)) == list(string_value[::-1])
+
+    def test_reverse_types(self):
+        from jinja2.filters import do_reverse
+
+        class Data(object):
+            def __init__(self):
+                self.__item = 1
+
+            def __iter__(self):
+                yield self.__item
+
+        no_sequence_data = Data()
+        # Test that will fail on reverse list iterator
+        # but will be caught by list construct
+        assert isinstance(do_reverse(value=no_sequence_data), list)
+
+        string_data = 'this is a string 42'
+        assert type(do_reverse(value=string_data)) is type(string_data)
+
+        list_data = [1, 2, 3, 4]
+        assert type(do_reverse(value=list_data)) is type(reversed(list_data))
+
     def test_string(self, env):
         x = [1, 2, 3, 4, 5]
         tmpl = env.from_string('''{{ obj|string }}''')

tests/test_regression.py

@@ -534,8 +534,66 @@ def resolve(self, name):
         assert x.resolve_or_missing('bar') == 23
         assert x.resolve_or_missing('baz') is missing
 
-    def test_recursive_loop_bug(self, env):
+    def test_recursive_loop_bug_1(self, env):
         tmpl = env.from_string('''
             {%- for value in values recursive %}1{% else %}0{% endfor -%}
         ''')
         assert tmpl.render(values=[]) == '0'
+
+    def test_revindex_one_length_list(self, env):
+        lst = [5]
+        tmpl = env.from_string('''
+                {%- for value in values|reverse %}{{loop.revindex}}|{{ value }}{% endfor -%}
+            ''')
+        result = tmpl.render(values=lst).split("|")
+        assert result[0] == '1'
+        assert result[1] == '5'
+
+    def test_revindex(self, env):
+        lst = [1, 5, 10]
+        tmpl = env.from_string('''
+                {%- for value in values|reverse %}{{loop.revindex}}|{{ value }}###{% endfor -%}
+            ''')
+        rows = tmpl.render(values=lst).split("###")[:-1]
+        assert len(lst) == len(rows)
+
+        item_row1 = rows[0].split("|")
+        assert item_row1[0] == '3'
+        assert item_row1[1] == '10'
+
+        item_row2 = rows[1].split("|")
+        assert item_row2[0] == '2'
+        assert item_row2[1] == '5'
+
+        item_row3 = rows[2].split("|")
+        assert item_row3[0] == '1'
+        assert item_row3[1] == '1'
+
+    def test_revindex_filter_exception(self, env):
+        from jinja2.exceptions import FilterArgumentError
+        lst = 42
+        tmpl = env.from_string('''
+                {%- for value in values|reverse %}{{loop.revindex}}|{{ value }}{% endfor -%}
+            ''')
+        with pytest.raises(FilterArgumentError):
+            tmpl.render(values=lst)
+
+    def test_revindex_revindex0_one_length_list(self, env):
+        lst = [5]
+        tmpl = env.from_string('''
+                {%- for value in values|reverse %}{{loop.revindex}}|{{loop.revindex0}}|{{ value }}{% endfor -%}
+            ''')
+        result = tmpl.render(values=lst).split("|")
+        assert result[0] == '1'
+        assert result[1] == '0'
+        assert result[2] == '5'
+
+    def test_loop_select_length_odd(self, env):
+        """ This test covers https://github.com/pallets/jinja/issues/751#issuecomment-359105157 """
+        lst = [0, 1, 2]
+        tmpl = env.from_string('''
+                {%- for value in values | select("odd") %}{{loop.length}}{% endfor -%}
+            ''')
+        result = tmpl.render(values=lst)
+
+        assert '1' == result