Fix a faulty form_for test

Stumbled upon this one while trying to deprecate the String/Symbol
passing to `form_for`.

This test passed on an accident, because the signature of `form_for`
currently accepts 2 positional arguments and a block. Calling it with
the wrong number of arguments caused:

```ruby
(byebug) form_for(:post, @post, html: { id: 'create-post' })
*** ArgumentError Exception: wrong number of arguments (3 for 1..2)
```

This made the test pass, because it was still an `ArgumentError`. :-)

0 files changed, 0 insertions, 0 deletions