Raise TypeError if the name given to importlib.__import__() lacks an rpartition

attribute. Was throwing AttributeError before. Discovered when running
test_builtin against importlib.

This exception change is specific to importlib.__import__() and does not apply to
import_module() as it is being done for compatibility reasons only.

Lib/importlib/_bootstrap.py

@@ -917,6 +917,8 @@ def __import__(name, globals={}, locals={}, fromlist=[], level=0):
     import (e.g. ``from ..pkg import mod`` would have a 'level' of 2).
 
     """
+    if not hasattr(name, 'rpartition'):
+        raise TypeError("module name must be str, not {}".format(type(name)))
     if level == 0:
         module = _gcd_import(name)
     else:

Lib/importlib/test/import_/test_api.py

@@ -0,0 +1,22 @@
+from . import util
+import unittest
+
+
+class APITest(unittest.TestCase):
+
+    """Test API-specific details for __import__ (e.g. raising the right
+    exception when passing in an int for the module name)."""
+
+    def test_name_requires_rparition(self):
+        # Raise TypeError if a non-string is passed in for the module name.
+        with self.assertRaises(TypeError):
+            util.import_(42)
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(APITest)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/regrtest.py

@@ -6,7 +6,6 @@ Otherwise all command-line options valid for test.regrtest are also valid for
 this script.
 
 XXX FAILING
-    test_builtin  # Wanting a TypeError for an integer name
     test_import  # execution bit, exception name differing, file name differing
                     between code and module (?)
     test_importhooks  # package not set in _gcd_import() but level > 0