Bowling Game

Level: Advanced 60–90 min

Concepts: Edge CasesState

Solutions: C# | TypeScript | Python

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Create a program to score a game of ten-pin bowling.

Requirements

1. Calculate the score for a game of ten-pin bowling
2. Handle all valid bowling scenarios:
   • Regular frames (sum of pins knocked down)
   • Spares (10 pins in two rolls, bonus is next roll)
   • Strikes (10 pins in one roll, bonus is next two rolls)
   • 10th frame special cases (up to three rolls)
3. Validate input:
   • Number of pins must be between 0 and 10
   • Sum of pins in a frame (except last) must not exceed 10
   • Proper number of rolls based on game progress

Test Cases

Scenario	Rolls	Score	Notes
All Gutter Balls	0,0, 0,0, 0,0, 0,0, 0,0, 0,0, 0,0, 0,0, 0,0, 0,0	0	No pins knocked down
All Ones	1,1, 1,1, 1,1, 1,1, 1,1, 1,1, 1,1, 1,1, 1,1, 1,1	20	One pin per roll
One Spare	5,5, 3,0, 0,0, 0,0, 0,0, 0,0, 0,0, 0,0, 0,0, 0,0	16	Spare + bonus
One Strike	10, 3,4, 0,0, 0,0, 0,0, 0,0, 0,0, 0,0, 0,0, 0,0	24	Strike + bonus
Perfect Game	10, 10, 10, 10, 10, 10, 10, 10, 10, 10,10,10	300	All strikes
All Spares	5,5, 5,5, 5,5, 5,5, 5,5, 5,5, 5,5, 5,5, 5,5, 5,5, 5,5,5	150	All spares

Edge Cases to Consider

• Invalid number of pins (>10 or <0)
• Invalid frame totals (>10 in a frame)
• Wrong number of rolls for the game state
• Invalid bonus rolls in 10th frame
• Empty or null input

Tips

• Start with the simplest case (all zeros)
• Add support for regular frames first
• Then add spares, then strikes
• Handle the 10th frame as a special case
• Consider using a Frame class to encapsulate frame logic

Reference Walkthrough

Full C#, TypeScript, and Python implementations live at tddbuddy-reference-katas/bowling-game — the same six scenarios across all three languages, walked commit-by-commit through the TDD cycle.

• C# (.NET 8, xUnit, FluentAssertions) — walkthrough
• TypeScript (Node 20, Vitest, strict types) — walkthrough
• Python (3.11, pytest) — walkthrough

This is a Pedagogy mode kata — the walkthroughs step through the TDD cycle commit-by-commit. Watch the gear shift from low (fake-it, sum) to middle once the scoring loop’s two-mode index (frame vs roll cursor) lands. The teaching point is the class that does not get written: two reflect — commits mark the moments the author was tempted to extract a Frame type and chose not to — the Frame concept lives in the rollIndex += 1 vs rollIndex += 2 advance, not in a class. See the repo’s Gears section for why resisting a premature abstraction is itself a TDD skill.