I will cover some major negative test cases to break the sign up page:


1)
See the limit of username field. I mean the data
type of this field in DB and the field size. Try adding more characters
to this field than the field size limit. See how application respond to
this.



2)

Repeat above case for number fields. Insert number beyond the field storage capacity. This is typically a boundary test.



3)

For username field try adding numbers and special
characters in various combinations. (Characters like
!@#$%^&*()_+}{”:?><,./;’[]). If not allowed specific message
should be displayed to the user.





4)


Try above special character combination for all the
input fields on your sign up page having some validations. Like Email
address field, URL field validations etc.



5)

Many applications crash for the input field
containing ‘ (single quote) and ” (double quote) examples field like:
“Manoj’s web”. Try it in all the input fields one by one.



6)

Try adding only numbers to input fields having validation to enter only characters and vice versa.



7)

If URL validation is there then see different rules
for url validation and add urls not fitting to the rules to observe the
system behavior.

Example urls like:
manoj.com/?q=manoj’s!@#$%^&*()_+}{”:?><,./;’[]web_page Also
add urls containing http:// and https:// while inserting into url input
box.





8 )


If your sign up page is of some steps like step 1
step 2 etc. then try changing parameter values directly into browser
address bar. Many times urls are formatted with some parameters to
maintain proper user steps. Try altering all those parameters directly
without doing anything actually on the sign up page.



9)

Do some monkey testing manually or automating (i.e.
Insert whatever comes in mind or random typing over keyboard) you will
come up with some observations.



10)

See if any page is showing JavaScript error either
at the browser left bottom corner or enable the browser settings to
display popup message to any JavaScript error.