1. An integrated method for validating the functionality and performance of software applications through multiple test phases using a common set of business requirements-based manual test scripts, the method comprising the steps of: deriving software application test conditions; generating manual test scripts based on the software application test conditions; creating, using at least one processor, functional tests for a functional test phase based on the generated manual test scripts; selecting, for an automated regression test phase, a first subset of the generated manual test scripts, the selecting based on attributes of the generated manual test scripts and the functional tests created for the functional test phase; creating automated regression tests for the automated regression test phase based on the selected first subset of manual test scripts, wherein creating automated regression tests comprises: identifying object types; identifying actions; creating reusable functions for each action identified; identifying identifiers for each unique object of the identified object types; creating automated functions based on the reusable functions and a plurality of reusable Extensible Markup Language (XML) objects; and creating automated test scripts including a plurality of the automated functions for the automated regressions test; and automatically executing the functional test phase and the automated regression test phase concurrently.