Quality is delighting customers
1) Yes we can write separate test cases for Integration testing ..
Being a black box tester our job is limited to test the functionality of the integration... hence ...
Integration testing test case :- Enter the Mandatory fields and Click the button and verify that it navigates to the corresponding page. here most of the cases we write Positive test case just to ensure that the modules are connected, and for doing that only mandatory fields are filled and the button is clicked ..
2) Design spec will help you in identifying the Interfaces .. the Primary focus during Integration testing is to ensure that Units are communicating properly after integration .. a tester tries to find out the defects in interfaces ( connection points )
Integration means :-- Combination of Units ... and Integration testing means : testing done on the integrated module... testing the Interfaces between components as well as interaction points of the Components ... we also test interactions with different parts of the system such as OS, File system etc........
Integration testing :- Modules are integrated properly and units are working properly even after the Integration. done against Design Spec.. test basis : System Design , Architecture , Workflows and UCs..
Hope it will help You..
Nicely Explained Samrat...
I am not getting your question... and Usability testing is a part of GUI testing itself ...!
When we develop products for certain client then we interact with them throughout the life cycle of the Product.. so the situation will not arise but in worst case if it happens, We will let our senior management decide over the issue.....