Add section about how to test with testkit (#555)

* Add section about how to test with testkit

* Update TESTING.md

Co-authored-by: Robsdedude <rouven.bauer@neotechnology.com>

Co-authored-by: Robsdedude <rouven.bauer@neotechnology.com>

Author: bigmontz

TESTING.md

@@ -37,3 +37,36 @@ $ NEO4J_USER=bob NEO4J_PASSWORD=secret tox
 If [Coverage](https://coverage.readthedocs.io/) is installed, test runs automatically add data to a `.coverage` file.
 To use this data, ensure that `coverage erase` is executed before commencing a test run;
 a report can be viewed after the run with `coverage report --show-missing`.
+
+## Testing with Testkit
+
+Tests **require** the latest [Testkit 4.3](https://github.com/neo4j-drivers/testkit/tree/4.3), Python3 and Docker.
+
+Testkit is needed to be cloned and configured to run against the Python Driver. Use the following steps to configure Testkit.
+
+1. Clone the Testkit repository—preferably not inside this project's folder
+
+```
+git clone https://github.com/neo4j-drivers/testkit.git
+```
+
+2. Under the Testkit folder, install the requirements.
+
+```
+pip3 install -r requirements.txt
+```
+
+3. Define some enviroment variables to configure Testkit
+
+```
+export TEST_DRIVER_NAME=python
+export TEST_DRIVER_REPO=<path for the root folder of driver repository>
+```
+
+To run test against against some Neo4j version:
+
+```
+python3 main.py
+```
+
+More details about how to use Teskit could be found on [its repository](https://github.com/neo4j-drivers/testkit/tree/4.3)