newField checks its input is a str

Indeed, it takes as input a name (str). For some reason in some test
it was given a model. This actually led to some strange failed test.

anki/models.py

@@ -231,6 +231,7 @@ and notes.mid = ? and cards.ord = ?""", m['id'], ord)
     ##################################################
 
     def newField(self, name):
+        assert(isinstance(name, str))
         f = defaultField.copy()
         f['name'] = name
         return f

tests/test_models.py

@@ -39,8 +39,7 @@ def test_fields():
     assert "{{NewFront}}" in m['tmpls'][0]['qfmt']
     h = d.models.scmhash(m)
     # add a field
-    f = d.models.newField(m)
-    f['name'] = "foo"
+    f = d.models.newField("foo")
     d.models.addField(m, f)
     assert d.getNote(d.models.nids(m)[0]).fields == ["1", "2", ""]
     assert d.models.scmhash(m) != h
@@ -57,8 +56,7 @@ def test_fields():
     d.models.moveField(m, m['flds'][1], 0)
     assert d.getNote(d.models.nids(m)[0]).fields == ["1", ""]
     # add another and put in middle
-    f = d.models.newField(m)
-    f['name'] = "baz"
+    f = d.models.newField("baz")
     d.models.addField(m, f)
     f = d.getNote(d.models.nids(m)[0])
     f['baz'] = "2"