TDD Exercise: Bus Fare Calculator

This project is a tutorial exercise to learn Test-Driven Development (TDD) using Python.

Case Description

You are building a function bus_ticket_price() that calculates the fare of a bus ride based on several rules:

• Children under 2 ride for free.
• Children under 18 and seniors over 65 pay half fare.
• Others pay the full fare of $3.
• On weekdays (Mon–Fri), between 7–9am and 4–6pm, add a $1.5 peak surcharge.
• On weekends, flat fare is $2 (except for children under 2).
• Short trips under 5 minutes during off-peak are free (except on weekends).
• On public holidays, a special $2 holiday surcharge is added (overrides other rules).

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Tasks

Step 1: Red Phase – Write the First Test

Go to tests/test_bus_fare.py and write a test for:

A 1-year-old child on a weekday should ride for free.

Step 2: Green Phase – Implement Minimum Code

Go to src/bus_fare.py and write the minimum code to make the test pass.

Step 3: Refactor

After the test passes, clean up the code to make it more readable and modular.

Step 4: Add More Tests

Complete the test cases for:

• Teenagers
• Adults
• Seniors
• Weekend pricing
• Public holiday surcharge
• Short trip logic

Follow the template code provided.

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Run the Tests

python -m unittest discover -s tests