"left" -> "accidentally placed at"

since "left" is kind of ambiguous, use more explicit terminology
here.

Also update the test to use a positive assertion that the
warning is emitted; quote the attribute name.

Change-Id: Ic2284c200a26b32b2da063cfaf6d59547309d587
References: https://github.com/zzzeek/sqlalchemy/pull/488
(cherry picked from commit eacb31a89f)

lib/sqlalchemy/ext/declarative/base.py

@@ -386,8 +386,8 @@ class _MapperConfig(object):
             if (isinstance(value, tuple) and len(value) == 1 and
                     isinstance(value[0], (Column, MapperProperty))):
                 util.warn("Ignoring declarative-like tuple value of attribute "
-                          "%s: possibly a copy-and-paste error with a comma "
-                          "left at the end of the line?" % k)
+                          "'%s': possibly a copy-and-paste error with a comma "
+                          "accidentally placed at the end of the line?" % k)
                 continue
             elif not isinstance(value, (Column, MapperProperty)):
                 # using @declared_attr for some object that

test/ext/declarative/test_basic.py

@@ -1122,23 +1122,17 @@ class DeclarativeTest(DeclarativeTestBase):
 
         eq_(Foo.__mapper__.CHECK, True)
 
-    @testing.emits_warning('Ignoring declarative-like tuple value of '
-                           'attribute id')
     def test_oops(self):
 
-        def define():
+        with testing.expect_warnings(
+            "Ignoring declarative-like tuple value of "
+                "attribute 'name'"):
 
             class User(Base, fixtures.ComparableEntity):
 
                 __tablename__ = 'users'
-                id = Column('id', Integer, primary_key=True),
-                name = Column('name', String(50))
-
-            assert False
-
-        assert_raises_message(sa.exc.ArgumentError,
-                              'Mapper Mapper|User|users could not '
-                              'assemble any primary key', define)
+                id = Column('id', Integer, primary_key=True)
+                name = Column('name', String(50)),
 
     def test_table_args_no_dict(self):