make inspect.isabstract() always return a boolean; add a test for it, too #7069

3 files changed, 26 insertions, 1 deletions

diff --git a/Lib/inspect.py b/Lib/inspect.py
index ac3434d..e5098d7 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -242,7 +242,7 @@ def isroutine(object):
 
 def isabstract(object):
     """Return true if the object is an abstract base class (ABC)."""
-    return isinstance(object, type) and object.__flags__ & TPFLAGS_IS_ABSTRACT
+    return bool(isinstance(object, type) and object.__flags__ & TPFLAGS_IS_ABSTRACT)
 
 def getmembers(object, predicate=None):
     """Return all members of an object as (name, value) pairs sorted by name.
diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index e4c4ee8..f20b26c 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -115,6 +115,29 @@ class TestPredicates(IsTestBase):
         self.assertTrue('a' in members)
         self.assertTrue('b' not in members)
 
+    def test_isabstract(self):
+        from abc import ABCMeta, abstractmethod
+
+        class AbstractClassExample(object):
+            __metaclass__ = ABCMeta
+
+            @abstractmethod
+            def foo(self):
+                pass
+
+        class ClassExample(AbstractClassExample):
+            def foo(self):
+                pass
+
+        a = ClassExample()
+
+        # Test general behaviour.
+        self.assertTrue(inspect.isabstract(AbstractClassExample))
+        self.assertFalse(inspect.isabstract(ClassExample))
+        self.assertFalse(inspect.isabstract(a))
+        self.assertFalse(inspect.isabstract(int))
+        self.assertFalse(inspect.isabstract(5))
+
 
 class TestInterpreterStack(IsTestBase):
     def __init__(self, *args, **kwargs):
diff --git a/Misc/NEWS b/Misc/NEWS
index cd6c930..276fc56 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -405,6 +405,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #7069: Make inspect.isabstract() return a boolean.
+
 - Add support to the `ihooks` module for relative imports.
 
 - Issue #6894: Fixed the issue urllib2 doesn't respect "no_proxy" environment