Python: Add test for ClassValue.isSequence() and isMapping()

For Python 3.6

python/ql/test/library-tests/PointsTo/class_properties/ClassValues.expected

@@ -0,0 +1,9 @@
+| mapping | builtin-class collections.defaultdict |
+| mapping | builtin-class dict |
+| neither sequence nor mapping | builtin-class set |
+| sequence | builtin-class bytes |
+| sequence | builtin-class collections.OrderedDict |
+| sequence | builtin-class list |
+| sequence | builtin-class str |
+| sequence | builtin-class tuple |
+| sequence | class OrderedDict |

python/ql/test/library-tests/PointsTo/class_properties/ClassValues.ql

@@ -0,0 +1,20 @@
+import python
+
+from ClassValue cls, string res
+where
+    exists(CallNode call |
+        call.getFunction().(NameNode).getId() = "test" and
+        call.getAnArg().pointsTo(cls)
+    ) and
+    (
+        cls.isSequence() and
+        cls.isMapping() and
+        res = "IS BOTH. SHOULD NOT HAPPEN. THEY ARE MUTUALLY EXCLUSIVE."
+        or
+        cls.isSequence() and not cls.isMapping() and res = "sequence"
+        or
+        not cls.isSequence() and cls.isMapping() and res = "mapping"
+        or
+        not cls.isSequence() and not cls.isMapping() and res = "neither sequence nor mapping"
+    )
+select res, cls.toString()

python/ql/test/library-tests/PointsTo/class_properties/options

@@ -0,0 +1 @@
+semmle-extractor-options: --max-import-depth=2

python/ql/test/library-tests/PointsTo/class_properties/test.py

@@ -0,0 +1,27 @@
+from collections import OrderedDict, defaultdict
+import collections.abc
+
+def test(*args):
+    pass
+
+test(
+    list,
+    tuple,
+    str,
+    bytes,
+    set,
+    dict,
+    OrderedDict,
+    defaultdict,
+)
+
+for seq_cls in (list, tuple, str, bytes):
+    assert issubclass(seq_cls, collections.abc.Sequence)
+    assert not issubclass(seq_cls, collections.abc.Mapping)
+
+for map_cls in (dict, OrderedDict, defaultdict):
+    assert not issubclass(map_cls, collections.abc.Sequence)
+    assert issubclass(map_cls, collections.abc.Mapping)
+
+assert not issubclass(set, collections.abc.Sequence)
+assert not issubclass(set, collections.abc.Mapping)