Beginner Testing Introduction

Version: v0.18.0

When to Use

• User's Vibe app ready to transition to Structured
• User mentions "testing" or "how to test"
• User has 3-4 features, wants quality assurance

Prerequisites

• Working Flask/Sinatra app with 3-4 features
• Understanding of routes and functions
• Code works but no tests

What is Testing?

Without tests: Change code → Open browser → Click around → Hope nothing broke With tests: Change code → Run tests → See green/red → Know immediately

TDD Cycle

RED → GREEN → REFACTOR

1. RED: Write test that fails (feature doesn't exist)
2. GREEN: Write just enough code to pass
3. REFACTOR: Clean up while tests still pass

Test Types (Simple)

Beginners: Start with route tests!

First Test (Flask)

# test_app.py
def test_homepage_loads():
    from app import app
    client = app.test_client()
    response = client.get('/')
    assert response.status_code == 200

Run: pip install pytest && pytest

First Test (Sinatra)

# test_app.rb
require 'minitest/autorun'
require 'rack/test'
require_relative 'app'

class AppTest < Minitest::Test
  include Rack::Test::Methods
  def app; Sinatra::Application; end

  def test_homepage_loads
    get '/'
    assert last_response.ok?
  end
end

Run: ruby test_app.rb

Common Assertions

Python: assert value == 5, assert 'text' in response.data Ruby: assert_equal 5, value, assert_includes body, 'text'

TDD Example: Delete Feature

# 1. RED - Write failing test
def test_delete_note():
    client = app.test_client()
    client.post('/add', data={'note': 'Test'})
    response = client.get('/delete/1')
    assert response.status_code == 302

# 2. GREEN - Make it pass
@app.route('/delete/<int:note_id>')
def delete_note(note_id):
    # implementation
    return redirect('/')

# 3. REFACTOR - Clean up

Test Output

Pass: 3 passed in 0.12s Fail: FAILED - AssertionError: assert 404 == 200

What to Test (Beginners)

• Routes exist (not 404)
• Forms submit successfully
• Data saves/displays correctly

Common Mistakes

Benefits

• Clarity: Test defines "working"
• Confidence: Know when things break
• Less fear: Change without worrying

End of Skill