How do I test ActionFilterAttributes that work with ModelState?
- by Tomas Lycken
As suggested by (among others) Kazi Manzur Rashid in this blog post, I am using ActionFilterAttributes to transfer model state from one request to another when redirecting.
However, I find myself unable to write a unit test that test the behavior of these attributes. As an example, this what I want the test for the ImportModelStateAttribute to do:
Setup the filterContext so that TempData[myKey] contains some fake "exported" ModelState (that is, a ModelStateDictionary I create myself, and add one error to)
Make ModelState contain one model error.
Call OnActionExecuting.
Verify the two dictionaries are merged, and ModelState now contains both errors.
I'm at a loss already on the second step.