The Apex Test Runner allows developers top execute test classes right from within the IDE. It provides the same functionality as the Apex Test Execution page in Salesforce.
Abort - Cancels the selected item(s).
Select Tests - Displays the Test Classes that are available within your instance.
Toggle Session - Show results from your current session or previous sessions.
Refresh - Refreshes the test results.
Clear - Clears the test results.