Unable to load multiple custom shape classes in web UI from --class-picker

[shamithas99]

Prerequisites

• I am using the latest version of Locust
• I am reporting a bug, not asking a question

Description

Why does locust load only the 1st LoadTestShape class in web UI, when there is more than 1 LoadTestShape class defined in locustfile?
In the docs we can see multiple shape classes appearing in the UI but unable to implement it.

Command line

locust -f locustfile.py --class-picker

Locustfile contents

from locust import HttpUser, TaskSet, task
from locust import LoadTestShape

class Tasks1(TaskSet):
    @task
    def service(self):
        print("Launching URL")

class FirstUser(HttpUser):
    tasks = [Tasks1]

class SecondUser(HttpUser):
    tasks = [Tasks1]

class ThirdUser(HttpUser):
    tasks = [Tasks1]

class FourthUser(HttpUser):
    tasks = [Tasks1]

class FifthUser(HttpUser):
    tasks = [Tasks1]

class ramp_up_1min_40users_hold_20min(LoadTestShape):
    stages = [
        {"duration": 60, "users": 40, "spawn_rate": 0.67},
        {"duration": 1200, "users": 40, "spawn_rate": 1},
    ]

    def tick(self):
        run_time = self.get_run_time()
        for stage in self.stages:
            if run_time < stage["duration"]:
                try:
                    tick_data = (
                        stage["users"], stage["spawn_rate"], stage["user_classes"])
                except:
                    tick_data = (stage["users"], stage["spawn_rate"])
                return tick_data
        return None

class ramp_up_20min_40users_hold_5min_ramp_down_5min_1user(LoadTestShape):
    stages = [
        {"duration": 1200, "users": 40, "spawn_rate": 0.034},
        {"duration": 300, "users": 40, "spawn_rate": 1},
        {"duration": 300, "users": 1, "spawn_rate": 0.0325}
    ]

    def tick(self):
        run_time = self.get_run_time()
        for stage in self.stages:
            if run_time < stage["duration"]:
                try:
                    tick_data = (
                        stage["users"], stage["spawn_rate"], stage["user_classes"])
                except:
                    tick_data = (stage["users"], stage["spawn_rate"])
                return tick_data
        return None

Python version

3.9

Locust version

2.16.1

Operating system

Windows

[cyberw]

2.15.1 is not latest version

[shamithas99]

2.15.1 is not latest version

It doesn't work in 2.16.1 either

[cyberw]

I can reproduce the error: The problem is that the class picker was only ever implemented for reading the shape classes from different files (e.g. using locust -f mylocustfile.py -f shape1.py -f shape2.py), if they are all in the same file it will not work: https://github.com/locustio/locust/blob/master/locust/main.py#L90

The class picker was implemented by @mikenester . I dont know if he has time to take a look.

[mikenester]

It's been a minute since I've touched this, but I can definitely take a look. @shamithas99 Thanks for the details & screenshots on your report 🙏

[shamithas99]

I can reproduce the error: The problem is that the class picker was only ever implemented for reading the shape classes from different files (e.g. using locust -f mylocustfile.py -f shape1.py -f shape2.py), if they are all in the same file it will not work: https://github.com/locustio/locust/blob/master/locust/main.py#L90

The class picker was implemented by @mikenester . I dont know if he has time to take a look.

I have tried to implement class picker with shape files in different files but we don't see all the shape files coming in the UI dropdown, if there is more than 1 shapefile.

[cyberw]

@mikenester Did you have time to investigate this?

[mikenester]

@cyberw Sorry, I've been quite busy and lost sight of this. I was trying to take a look today, but while setting up the project, I'm getting the following error when running pip3 install -e locust/

ERROR: File "setup.py" or "setup.cfg" not found. Directory cannot be installed in editable mode: /Users/michaelnester/git/locust
(A "pyproject.toml" file was found, but editable mode currently requires a setuptools-based build.)

I'm guessing I need to force it to use pyproject.toml, but am not sure how. Any suggestions?

[cyberw]

Try updating setuptools and pip to latest versions.

[mikenester]

That worked. Thanks 🙏

I suspect this is the offending block of code. I'll try to have a fix soon.

[mikenester]

I think I have a fix. I need to add tests and check for edge cases, then I'll open up a pull request.

[mikenester]

@cyberw I've opened a PR: #2441. I also included a fix for a legacy UI styling issue, which was quite minor.