Locust AttributeError: object has no attribute

Question

I am using python 3.10 and here is my locust file.

from locust import HttpUser, task, between
import string
import random
import time
import datetime

WAIT_TIME_MIN = 1
WAIT_TIME_MAX = 5

h = {
    "Content-Type": "application/json"
}

random.seed()

class LoadTest(HttpUser):
    wait_time = between(WAIT_TIME_MIN, WAIT_TIME_MAX)
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.path = None

    def generate_random_string(self, min_name_size=2, max_name_size=20) -> str:
        letters = string.ascii_lowercase
        string_size = random.randint(min_name_size, max_name_size)
        generated_string = ''.join(random.choice(letters) for i in range(string_size))
        return generated_string
    
    def generate_random_dob(self) -> str:
        d = random.randint(1, int(time.time()))
        return datetime.date.fromtimestamp(d).strftime('%Y-%m-%d')
    
    @task(2)
    def get_all(self):
        self.client.get(url=self.path)
    
    @task(8)
    def post_request(self):
        self.client.post(url=self.path, json=self._generate_post_data(), headers=h)


class TeacherProcess(LoadTest):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.path = "/api/v1/teacher"
        
    def _generate_post_data(self):
        request_data = {
            "teacherName": str,
            "teacherEmail": str,
            "teacherDOB": str
        }
        request_data["teacherName"] = self.generate_random_string()
        request_data["teacherEmail"] = f"{self.generate_random_string()}@{self.generate_random_string()}.{self.generate_random_string()}"
        request_data["teacherDOB"] = self.generate_random_dob()

        return request_data


class StudentProcess(LoadTest):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.path = "/api/v1/student"

    def _generate_post_data(self):
        request_data = {
            "studentName": str,
            "studentEmail": str,
            "studentDOB": str
        }
        request_data["studentName"] = self.generate_random_string()
        request_data["studentEmail"] = f"{self.generate_random_string()}@{self.generate_random_string()}.{self.generate_random_string()}"
        request_data["studentDOB"] = self.generate_random_dob()

        return request_data

I don't know how but somehow I am able to use _generate_post_data inside LoadTest class. I am telling it's working because locust output as below:

Type     Name                                                                          # reqs      # fails |    Avg     Min     Max    Med |   req/s  failures/s
--------|----------------------------------------------------------------------------|-------|-------------|-------|-------|-------|-------|--------|-----------
GET      /api/v1/student                                                                  126     0(0.00%) |     36       2     117      7 |   12.78        0.00
POST     /api/v1/student                                                                  499     0(0.00%) |     66       1     276      6 |   50.61        0.00
GET      /api/v1/teacher                                                                  135     0(0.00%) |     53       2     233      8 |   13.69        0.00
POST     /api/v1/teacher                                                                  502     0(0.00%) |     60       2     238      6 |   50.92        0.00
--------|----------------------------------------------------------------------------|-------|-------------|-------|-------|-------|-------|--------|-----------
         Aggregated                                                                      1262     0(0.00%) |     59       1     276      7 |  128.00        0.00

Response time percentiles (approximated)
Type     Name                                                                                  50%    66%    75%    80%    90%    95%    98%    99%  99.9% 99.99%   100% # reqs
--------|--------------------------------------------------------------------------------|--------|------|------|------|------|------|------|------|------|------|------|------
GET      /api/v1/student                                                                         7     10    110    110    110    110    120    120    120    120    120    126
POST     /api/v1/student                                                                         6     10    200    220    250    260    260    270    280    280    280    499
GET      /api/v1/teacher                                                                         8     10    110    140    230    230    230    230    230    230    230    135
POST     /api/v1/teacher                                                                         6      9    180    200    220    230    230    230    240    240    240    502
--------|--------------------------------------------------------------------------------|--------|------|------|------|------|------|------|------|------|------|------|------
         Aggregated                                                                              7     10    110    190    230    240    260    260    270    280    280   1262

As you can see there is no failure. My question is how I am able to access _generate_post_data while I am inside the LoadTest class? The second one is related to below error:

[2023-01-25 12:31:38,147] pop-os/ERROR/locust.user.task: 'LoadTest' object has no attribute '_generate_post_data'
Traceback (most recent call last):
  File "/home/ak/.local/lib/python3.10/site-packages/locust/user/task.py", line 347, in run
    self.execute_next_task()
  File "/home/ak/.local/lib/python3.10/site-packages/locust/user/task.py", line 372, in execute_next_task
    self.execute_task(self._task_queue.pop(0))
  File "/home/ak/.local/lib/python3.10/site-packages/locust/user/task.py", line 493, in execute_task
    task(self.user)
  File "/home/ak/Desktop/my-projects/spring-boot-app/performans-testing/locust.py", line 38, in post_request
    self.client.post(url=self.path, json=self._generate_post_data(), headers=h)
AttributeError: 'LoadTest' object has no attribute '_generate_post_data'

I am quite confused, is that a locust bug, or am I doing something wrong? While locust doesn't show any failure, while I am having this error. If anyone can explain that, I would be appreciated

Answer 1

You need to inform Locust not to instantiate users based on the parent LoadTest class.

class LoadTest(HttpUser):
    abstract = True
    ...