type tests use isinstanceisinstance-tests

3 files changed, 9 insertions, 13 deletions

diff --git a/CHANGES.rst b/CHANGES.rst
index 9e26dff..4467887 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -8,6 +8,10 @@ Unreleased
 -   Drop support for Python 2.7 and 3.5.
 -   Bump MarkupSafe dependency to >=1.1.
 -   Bump Babel optional dependency to >=2.1.
+-   Rather than checking for attributes, ``is sequence`` tests against
+    :class:`~collections.abc.Sequence`, ``is iterable`` tests against
+    :class:`~collections.abc.Iterable`, and ``is escaped`` tests against
+    :class:`~markupsafe.Markup`.
 
 
 Version 2.11.0
diff --git a/src/jinja2/tests.py b/src/jinja2/tests.py
index fabd4ce..2f9d23f 100644
--- a/src/jinja2/tests.py
+++ b/src/jinja2/tests.py
@@ -4,6 +4,8 @@ import decimal
 import operator
 import re
 
+from markupsafe import Markup
+
 from ._compat import abc
 from ._compat import integer_types
 from ._compat import string_types
@@ -131,12 +133,7 @@ def test_sequence(value):
     """Return true if the variable is a sequence. Sequences are variables
     that are iterable.
     """
-    try:
-        len(value)
-        value.__getitem__
-    except Exception:
-        return False
-    return True
+    return isinstance(value, abc.Sequence)
 
 
 def test_sameas(value, other):
@@ -154,16 +151,12 @@ def test_sameas(value, other):
 
 def test_iterable(value):
     """Check if it's possible to iterate over an object."""
-    try:
-        iter(value)
-    except TypeError:
-        return False
-    return True
+    return isinstance(value, abc.Iterable)
 
 
 def test_escaped(value):
     """Check if the value is escaped."""
-    return hasattr(value, "__html__")
+    return isinstance(value, Markup)
 
 
 def test_in(value, seq):
diff --git a/tests/test_tests.py b/tests/test_tests.py
index 42595e8..84f9e2d 100644
--- a/tests/test_tests.py
+++ b/tests/test_tests.py
@@ -86,7 +86,6 @@ class TestTestsCase(object):
             ('"foo" is sequence', True),
             ("[] is sequence", True),
             ("[1, 2, 3] is sequence", True),
-            ("{} is sequence", True),
             ("none is mapping", False),
             ("false is mapping", False),
             ("42 is mapping", False),