You can put the script anywhere in your django project

Then you need to use the following line of code in settings.py

TEST_RUNNER = 'path.DiscoverSlowestTestsRunner' # the path is where you put the script

When you run the djagno test you can have addition commands:

--time=300,The console will output the execution time of each test instead of the test run info. while the time is greater than 300 ms, it will turn red.

--report=300 When all test runs are completed, the console will output a test report with a run time greater than 300 ms.

--limit=15 The final test report will only show the slowest 15 data