added testing documentation

README.md

@@ -29,6 +29,7 @@ The extension is licensed under [AGPL-3.0](LICENSE.txt).
 * [Add your own data source for a CiviCRM Entity](docs/add_your_own_datasource.md)
 * Add your own data source for a CSV File
 * How to store a data processor in code in your extension
+* [Develop PHPUnit TestCase for the extension](docs/how_to_create_test.md)
 
 ## Installation
 

docs/how_to_create_test.md

+# How to create a PHPUnit Test
+
+- Create file with appropriate name ending with test. For Example `CreateDataProcessorTest.php`
+- Follow the simplest test case file `CreateDataProcessorTest.php` for creating a test case.
+- Create a function whose name starting with test. For Example `testCreateDataProcessor`. All the function starting with **test** will be evaluated, so name your utility functions properly.
+- If you want to reset the Test Database and install from beginning pass `True` in `apply()` function in `setupHeadless() function`.
+- Don't remove `setUp()` and `tearDown()` function from the UnitTest file.
+