how can i conect parasoft(Soatest) with Salesforce so that i may be able to run some test or which tool is the best for testing metadata and code in Salesforce?

Alkso for suggested tools,here is the list:

• AutoRABIT has rich support for Salesforce Test Automation
• Test Tracker Professional in ApExchange is to manage the core application testing
• check out Provar - the automated testing app for Salesforce