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How To Unit Test a Flask Restful Get Endpoint Using Python

In this article, we are going to explore how to unit test a simple GET restful endpoint using Python 3 and the modules Flask, Flask_restx, and UnitTest.

Creating The Application​

First, we are going to create a simple flask application, the application will host a GET endpoint called /Settings that returns a list of setting names and values in JSON format.

  • Create a text file called endPointGet.py and add the following code.
from flask import Flask
from flask_restx import Namespace, Resource, Api, fields, reqparse
from flask_cors import CORS

app = Flask(__name__)
CORS(app)  # Allow CORS for all routes
api = Api(app, version='1.0', title='EndPoint Get', description='Example Restful Service')

mySettingsData = [
            {'Name': 'Setting1', 'Value': 'Value1'},
            {'Name': 'Setting2', 'Value': 'Value2'}
        ]

@api.route('/Settings', doc={"description": "Get all settings"})
class GetSettings(Resource):
    def get(self):
        return mySettingsData
        
if __name__ == '__main__':
    app.run(host='0.0.0.0', port=5500, debug=False)

Running The Application​

To run the application:

  • From the terminal execute the python file. python endPointGet.py

1

  • Open a web browser and navigate to http://127.0.0.1:5500, the page will show the swagger document for the Flask application. 2

  • Click default to expand the list of endpoints

  • Click the GET button next to /Settings. 3

  • Click the Try it out button. 4

  • Click the Execute button. 5

  • The response to the request will be displayed in the response body section. 6

Unit Testing The Application​

To unit test the flask application:

  • Create a text file called endPointGetTests.py and add the following code
import unittest
import json
from endPointGet import *

class SystemSettingsTestCase(unittest.TestCase):
    def setUp(self):
        """Set up for unit tests, function is executed before tests begin"""

        self.client = app.test_client()
        app.config['TESTING'] = True

    def test_get_settings(self):
        """Test confirms that GET /Settings will return a list of all the system settings"""

        # Arrange 
        expected_result = [
            {'Name': 'Setting1', 'Value': 'Value1'},
            {'Name': 'Setting2', 'Value': 'Value2'}
        ]

        # Act
        response = self.client.get('/Settings') # Make a GET request to the /Settings endpoint

        # Assert
        self.assertEqual(response.status_code, 200) # Check that the response status code is 200 OK
        actual_result = json.loads(response.data) # Parse the JSON response        
        self.assertEqual(actual_result, expected_result) # Check that the response contains the expected data

if __name__ == '__main__':
    unittest.main()
  • To run the test, execute the Python file endPointGetTests.py from the terminal.

python endPointGetTests.py

  • The log messages from a successful test will end with OK. 7

  • The log messages from a failed test will end with the number of failures. 8

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