Added blocks to start and edit

[TWoeste]

This will allow people to add different options to start and edit a test with.

[TWoeste]

PR for #1822 (comment)
@cyberw

[cyberw]

I dont understand how this would work and it needs some documentation and ideally a test case.

[TWoeste]

{% block extended_start %}{% endblock extended_start %} & {% block extended_edit %}{% endblock extended_edit %}

The two lines added are block statements that work the same way as the three already added block statements do. It will allow the user to add html code inside these blocks to extend the way their code starts and stops load tests. You can couple this with the scripts block at the bottom of index.html to handle the requests and in turn start the load tests. I am not sure of a good way to write tests for this addition. If you point me towards a place you may want more documentation I will. The current place that has the documentation for the currently added blocks is just a example project that uses them.

[cyberw]

I guess you can add the example in a new folder under examples, like the other example. Explain what it does and link it from the same place (extending-locust.rst / https://docs.locust.io/en/stable/extending-locust.html#extending-web-ui)

I guess a test may be overly ambitious. You can skip that.

[TWoeste]

@cyberw Just added an example to the examples file.
I had to change where the blocks statements were in the code because with how the extending framework is set up I need the user to click a button to submit the changes of the new forms to a new route in the backend.

That is what the example UI looks like. Let me know if you have any other suggestions 😄

[cyberw]

Hmm. This is really a nice feature and I understand why you'd want it. But I think we need to make it nicer & more integrated into Locust.

Locust already has a (poorly documented) way to add custom arguments https://docs.locust.io/en/latest/api.html#locust.event.Events.init_command_line_parser (example usage: https://github.com/locustio/locust/blob/master/examples/add_command_line_argument.py)

If we just showed any custom arguments as input fields it would be very flexible and much easier for the user to use (no need to know jinja to be able to add arguments)

It would also be nice to make an "advanced" tab that lists all the arguments (but that is just nice to have, and some arguments are not possible to change at test start time)

[TWoeste]

Hmm ya that would probably be a more sustainable way to add custom starts params. I do not have the time now to make all of that so I will probably just proceed with my private fork. Thanks for you help.
You can close this PR if you want to.

[cyberw]

Ok!