Fixed call to ugettext, which is imported as _.

Changed raise to conform to PEP 3109 and wrapped the long line.
Added beginnings of tests for model fields.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@5778 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/regressiontests/model_fields/tests.py

@@ -0,0 +1,18 @@
+"""
+>>> from django.db.models.fields import *
+
+# DecimalField
+
+>>> f = DecimalField()
+
+>>> f.to_python(3)
+Decimal("3")
+
+>>> f.to_python("3.14")
+Decimal("3.14")
+
+>>> f.to_python("abc")
+Traceback (most recent call last):
+...
+ValidationError: [u'This value must be a decimal number.']
+"""