There are two (actually both are very similar) techniques in order to reveal the tests which tend to be "false/positive" ones – Error Seeding and Mutation Testing.

The both principles are based on introducing the errors in the application's program code, mainly in the places where it will have the most dramatical effect for application.

It can be for example changing the values of boolean operators (from "true" to "false") or some arithmetic operations (from "==" to ">=") in order to see whether the test which is covering this functionality will fail or not.

There are a plenty of frameworks which automatically do that job for you. Please find related info in the already existing topic on StackOverflow.

If you want to take a deeper look into theory of Error Seeding/Mutation Testing, the good start can be this presentation.

There are two (actually both are very similar) techniques in order to reveal the tests which tend to be "false/positive" ones – Error Seeding and Mutation Testing.

The both principles are based on introducing the errors in the application's program code, mainly in the places where it will have the most dramatical effect for application.

It can be for example changing the values of boolean operators (from "true" to "false") or some arithmetic operations (from "==" to ">=") in order to see whether the test which is covering this functionality will fail or not.

There are a plenty of frameworks which automatically do that job for you. Please find related info in the already existing topic on StackOverflow.

If you want to take a deeper look into theory of Error Seeding/Mutation Testing, the good start can be this presentation.