Test Harness

In software testing, a test harness or automated test framework is a collection of software and test data configured to test a program unit by running it under varying conditions and monitor its behavior and outputs.
It has two main parts:
-The test execution engine and
-The test script repository.

Test harnesses allow for the automation of tests. It can call functions with supplied parameters and print out and compare the results to the desired value. Test harness is a hook to the developed code which can be tested using automation framework.
To give testers hook for automating the test suites, A Test Harness should allow specific tests to run (this helps in optimising), simulate a runtime environment, and provide a capability to analyse results.

Test harnesses should include the following capabilities:

-A standard way to specify setup (i.e., creating an artificial runtime environment) and cleanup.
-A method for selecting individual tests to run, or all tests.
-A means of analyzing output for expected (or unexpected) results.
-A standardized form of failure reporting.

Hope this helps,
Kunal Shekhar.