dasty-api 0.3.2

Declarative API Scenario Testing in YAML - Easily define and run API tests using YAML.

Dasty: Declarative API Scenario Testing in YAML

Dasty is a Python package designed to simplify the process of testing APIs by allowing tests to be defined declaratively in YAML format. This approach enables easy-to-write, easy-to-read API test scenarios, making API testing more accessible and maintainable.

Features

• Declarative Syntax: Define API tests in a simple, human-readable YAML format.
• Flexible Test Scenarios: Support various HTTP methods and validations.
• Easy Variable Substitution: Define and use variables within your YAML test scenarios.
• Dynamic Variable Passing Between Steps: Extract and reuse values from responses in subsequent steps.

Installation

To install Dasty, simply use pip:

pip install dasty_api

Usage

Quickstart

This repository comes with a sample server and Scenarios that can be used for quick hands-on sandboxing.

To run these Scenarios, do the following:

0. From the examples sub-directory

cd ./examples

1. Install the dependencies required for the examples

pip install -r requirements.txt

2. Run the simple server. This will create a simple server that listens on localhost:2396

python3 simple_server.py

3. In a new terminal, run the ScenarioRunner

python3 scenario_runner.py

4. If successful, the output should look as follows:

Running scenario Add, Get, and Delete Users defined in examples/scenarios/add_get_delete_users.yaml...
        Running step Reset the server's memory... Success ✅
        Running step Get existing users... Success ✅
        Running step Add a new user... Success ✅
        Running step Get existing users, check that Dave was added... Success ✅
        Running step Delete a user... Success ✅
        Running step Get existing users, check that Charlie was deleted... Success ✅
        Running step Try to delete a user that doesn't exist... Success ✅
Add, Get, and Delete Users Success ✅
Running scenario Sample Service: Health Checks defined in examples/scenarios/healthchecks.yaml...
        Running step Health Check... Success ✅
        Running step Readiness Check... Success ✅
Sample Service: Health Checks Success ✅

Using dasty in your project

Dasty allows you to define your API test scenarios in YAML files. Here's a basic example:

name: "Users Service: Health Checks"
description:
  - "Health checks for the Users service"
variables:
  BASE_URL: "http://127.0.0.1:8003/api/v1/"
steps:
  - name: "Health Check"
    method: "GET"
    url: "${BASE_URL}/healthz"
    expected_status_code: 200
  - name: "Readiness Check"
    method: "GET"
    url: "${BASE_URL}/readyz"
    expected_status_code: 200

More examples can be found in the examples subdirectory.

The recommended structure is creating a folder named dasty_tests, containing a sub-folder named scenarios, containing the Scenario YAML files, along with a scenario_runner.py file which looks like:

from dasty_api.ScenarioRunner import ScenarioRunner

if __name__ == "__main__":
    runner = ScenarioRunner("./scenarios")
    runner.run()

Then, the dasty-tests folder should look like:

.
├── scenario_runner.py
└── scenarios
    ├── ...
    └── sample_scenario.yaml

Once main.py is executed, the output should look as follows:

╰─ python3 main.py                                              
Running scenario Users Service: Health Checks defined in scenarios/healthcheck_users.yaml...
        Running step Health Check... Success ✅
        Running step Readiness Check... Success ✅
Users Service: Health Checks Success ✅

Features

Dynamic Variable Passing

Dasty supports dynamic variable passing between steps in a scenario. This allows you to extract values from the response of one step and use them in subsequent steps. For example:

steps:
  - name: "Get user ID"
    method: "GET"
    url: "${BASE_URL}/users/name=John"
    extract:
      - name: user_id
        from: id
  - name: "Use the User ID in another request"
    method: "GET"
    url: "${BASE_URL}/users/id=${user_id}"

Response Validation Assertions

Dasty supports a variety of response assertion features to validate API response content.

response_includes

This assertion ensures specific content is included in the API response. It's essential for verifying the presence of expected data elements. For instance, to confirm that a user object is part of the response, response_includes can be used to assert its existence.

Usage Example:

- name: "Check user presence"
  method: "GET"
  url: "${BASE_URL}/users"
  expected_status_code: 200
  response_includes:
    users:
      - name: "Alice"

In this example, response_includes will validate that within the users array of the response, there is an entry with the name attribute equal to "Alice".

A practical example of this feature can be seen in this scenario

response_excludes

Conversely, this assertion ensures that certain content is definitively absent from the response. It is invaluable for confirming that sensitive data is not exposed or to ensure that an entity has been properly removed or is not present.

Usage Example:

- name: "Validate user absence"
  method: "GET"
  url: "${BASE_URL}/users"
  expected_status_code: 200
  response_excludes:
    users:
      - name: "Alice"

The response_excludes assertion checks that the users array in the response does not contain any object with a name attribute equal to "Alice".

With these two assertions, response_includes and response_excludes, testing for both the presence and absence of data in your API responses becomes straightforward and clear, providing a robust method for validating the state and security of your API endpoints.

A practical example of this feature can be seen in this scenario