With Spring ’16 Salesforce has released a new feature which helps to run multiple test classes at once.

Suppose you have 50 test classes in your org on Opportunity object and every time any developer makes any change in your apex code you want to make sure that test cases are no failing so you manually run every single class by going to

Setup-> Apex test execution

but with Test Suites rather than selecting all the relevant classes each time, you can simply run test suites. you can bundle them inside one Test Suites which can be run from Developer Console.

  1. In the Developer Console, select Test | New Suite Apex Test Suite in Salesforce
  2. Enter a name for your test suite, and then click OK.
  3. Use the arrows to move classes between the Available Test Classes column and the Selected Test Classes column, and then click Save.
  4. To run suites of test classes, select Test | New Suite Run.