Testing routes and responses in Flask - Mini Project: Build & Apply

Testing routes and responses

📖 Scenario: You are building a simple web app using Flask. You want to make sure your routes return the correct responses.

🎯 Goal: Create a Flask app with one route, then write tests to check the route's response status code and content.

📋 What You'll Learn

Create a Flask app with a route /hello that returns 'Hello, World!'

Create a test client to test the Flask app

Write a test to check the status code of the /hello route is 200

Write a test to check the response data of the /hello route contains 'Hello, World!'

💡 Why This Matters

🌍 Real World

Testing routes ensures your web app works correctly before users see it. It helps catch bugs early.

💼 Career

Web developers often write tests for their APIs and web routes to maintain quality and reliability.

1

Create a Flask app with a route

Create a Flask app called app and add a route /hello that returns the string 'Hello, World!'.

Flask

# Your code here

Need a hint?

Use Flask(__name__) to create the app and @app.route('/hello') to define the route.

2

Create a test client

Create a test client from the app by calling app.test_client() and assign it to a variable called client.

Flask

from flask import Flask

app = Flask(__name__)

@app.route('/hello')
def hello():
    return 'Hello, World!'

# Create a test client called client
# Your code here

Need a hint?

Use app.test_client() to create the test client.

3

Write a test for status code

Use the client to send a GET request to '/hello' and assign the response to a variable called response. Then check if response.status_code equals 200.

Flask

from flask import Flask

app = Flask(__name__)

@app.route('/hello')
def hello():
    return 'Hello, World!'

client = app.test_client()

# Send GET request to '/hello' and assign to response
# Check if response.status_code == 200
# Your code here

Need a hint?

Use client.get('/hello') to get the response and check response.status_code.

4

Write a test for response content

Check if the response.data contains the bytes of 'Hello, World!' by asserting b'Hello, World!' in response.data.

Flask

from flask import Flask

app = Flask(__name__)

@app.route('/hello')
def hello():
    return 'Hello, World!'

client = app.test_client()

response = client.get('/hello')
assert response.status_code == 200

# Assert that b'Hello, World!' is in response.data
# Your code here

Need a hint?

Remember response data is bytes, so use b'Hello, World!'.