Bowling Game Kata in C# Adapted

Bowling Game KataAdapted for C# and nUnit
By Dan Stewart (with modifications by Mike Clement)
dan@stewshack.com
mike@softwareontheside.com

Scoring Bowling.
The game consists of 10 frames as shown above. In each frame the player has two opportunities to knock down 10 pins. The score for the frame is the total number of pins knocked down, plus bonuses for strikes and spares.
A spare is when the player knocks down all 10 pins in two tries. The bonus for that frame is the number of pins knocked down by the next roll. So in frame 3 above, the score is 10 (the total number knocked down) plus a bonus of 5 (the number of pins knocked down on the next roll.)
A strike is when the player knocks down all 10 pins on his first try. The bonus for that frame is the value of the next two balls rolled.
In the tenth frame a player who rolls a spare or strike is allowed to roll the extra balls to complete the frame. However no more than three balls can be rolled in tenth frame.

A quick design session
Clearly we need the Game class.

A game has 10 frames.

A frame has 1 or two rolls.

The tenth frame has two or three rolls.
It is different from all the other frames.

The score function must
include all the frames,
and calculate all their scores.

The score for a spare or a strike depends on the frame’s successor

Begin.
Create a class library named BowlingGameKata

Begin.
Add a test fixture named BowlingGameTests to the project
usingNUnit.Framework;
namespaceBowlingGameKata
{
[TestFixture]
publicclassBowlingGameTests
{
[Test]
publicvoidGutterGameTest()
{
}
}
}

The first test.
[Test]
{
Game g = new Game();
}

The first test.
namespaceBowlingGameKata
{
publicclassGame
{
}
}
[Test]
{
}

The first test.
[Test]
{
}
publicclassGame
{
}

The first test.
[Test]
{
Gameg = newGame();
for(int i = 0; i < 20; i++)
{
g.Roll(0);
}
}
publicclassGame
{
}

The first test.
public class Game
{
publicvoid Roll(int p)
{
thrownewSystem.NotImplementedException();
}
}
[Test]
{
Gameg = newGame();
for(int i = 0; i < 20; i++)
{
g.Roll(0);
}
}

The first test.
[Test]
{
Gameg = newGame();
for(int i = 0; i < 20; i++)
{
g.Roll(0);
}
Assert.That(g.Score(), Is.EqualTo(0));
}
public class Game
{
{
thrownewSystem.NotImplementedException();
}
}

The first test.
[Test]
{
Gameg = newGame();
for(int i = 0; i < 20; i++)
{
g.Roll(0);
}
}
publicclassGame
{
{
thrownew System.NotImplementedException();
}
publicobject Score()
{
thrownew System.NotImplementedException();
}
}
Failed GutterGameTestthrew exception

The first test.
[Test]
{
Gameg = newGame();
for(int i = 0; i < 20; i++)
{
g.Roll(0);
}
}
publicclassGame
{
privateint score;
publicvoid Roll(int pins)
{
}
publicintScore()
{
returnscore;
}
}

The Second test.
[Test]
publicvoidAllOnesTest()
{
Gameg = newGame();
for(int i = 0; i < 20; i++)
{
g.Roll(1);
}
}
publicclassGame
{
privateint score;
{
}
publicintScore()
{
returnscore;
}
}

The Second test.
- Game creation is duplicated
- roll loop is duplicated
[Test]
{
Gameg = newGame();
for(int i = 0; i < 20; i++)
{
g.Roll(1);
}
}
publicclassGame
{
privateint score;
{
}
publicintScore()
{
returnscore;
}
}

The Second test.
- Game creation is duplicated
[Test]
{
Gameg = newGame();
for(int i = 0; i < 20; i++)
{
g.Roll(1);
}
}
publicclassGame
{
privateint score;
{
}
publicintScore()
{
return score;
}
}
Assert.AreEqual failed. Expected:<20>. Actual:<0>.

The Second test.
privateGame g;
[SetUp]
publicvoidSetup()
{
g = newGame();
}
[Test]
{
for(int i = 0; i < 20; i++)
{
g.Roll(0);
}
}
[Test]
{
for(int i = 0; i < 20; i++)
{
g.Roll(1);
}
}
publicclassGame
{
privateint score;
{
score += pins;
}
publicint Score()
{
return score;
}
}

The Second test.
[Test]
{
int rolls = 20;
intpins = 0;
for(int i = 0; i < rolls; i++)
{
g.Roll(pins);
}
}
publicclassGame
{
privateint score;
{
score += pins;
}
publicint Score()
{
return score;
}
}

The Second test.
[Test]
{
int rolls = 20;
intpins = 0;
RollMany(rolls, pins);
{
g.Roll(pins);
}
}
publicclassGame
{
privateint score;
{
score += pins;
}
publicint Score()
{
return score;
}
}

The Second test.
publicclassGame
{
privateint score;
{
score += pins;
}
publicint Score()
{
return score;
}
}
[Test]
{
RollMany(20, 0);
}
privatevoidRollMany(introlls, int pins)
{
{
g.Roll(pins);
}
}

The Second test.
[Test]
{
RollMany(20, 0);
}
[Test]
{
RollMany(20, 1);
}
privatevoidRollMany(int rolls, int pins)
{
{
g.Roll(pins);
}
}
publicclassGame
{
privateint score;
{
score += pins;
}
publicint Score()
{
return score;
}
}

The Third test.
- ugly comment in test.
[Test]
publicvoidOneSpareTest()
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
}
publicclassGame
{
privateint score;
{
score += pins;
}
publicint Score()
{
return score;
}
}
Failed Assert.AreEqual Expected:<16>. Actual:<13>

The Third test.
publicclassGame
{
privateint score;
{
score += pins;
}
publicint Score()
{
return score;
}
}
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
}
tempted to use flag to remember previous roll. So design must be wrong.

The Third test.
Roll() calculates score, but name does not imply that.
publicclassGame
{
privateint score;
{
score += pins;
}
publicint Score()
{
return score;
}
}
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
Assert.AreEqual(16, g.Score);
}
Score() does not calculate score, but name implies that it does.
Design is wrong. Responsibilities are misplaced.

The Third test.
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
//Assert.That(g.Score(), Is.EqualTo(16));
}
publicclassGame
{
privateint score;
{
score += pins;
}
publicint Score()
{
return score;
}
}

The Third test.
publicclassGame
{
privateint score;
privateint[] rolls = newint[21];
privateint currentRoll;
{
rolls[currentRoll++] = pins;
score += pins;
}
publicint Score()
{
return score;
}
}
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
}

The Third test.
publicclassGame
{
{
}
publicint Score()
{
int score = 0;
for (int i = 0; i < rolls.Length; i++)
{
score += rolls[i];
}
return score;
}
}
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
}

The Third test.
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
}
publicclassGame
{
{
}
publicint Score()
{
int score = 0;
{
score += rolls[i];
}
return score;
}
}

The Third test.
publicint Score()
{
int score = 0;
{
// spare
if(rolls[i] + rolls[i+1] == 10)
{
score += ...
}
score += rolls[i];
}
return score;
}
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
}
This isn’t going to work because i might not refer to the first ball of the frame.
Design is still wrong.
Need to walk through array two balls (one frame) at a time.

The Third test.
publicclassGame
{
{
}
publicint Score()
{
int score = 0;
{
score += rolls[i];
}
return score;
}
}
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
Assert.Inconclusive();
}

The Third test.
publicint Score()
{
int score = 0;
inti = 0;
for (int frame = 0; frame < 10; frame++)
{
score += rolls[i] + rolls[i + 1];
i+= 2;
}
returnscore;
}
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
Assert.Inconclusive();
}

The Third test.
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
}
publicint Score()
{
int score = 0;
int i = 0;
{
i += 2;
}
return score;
}

The Third test.
publicint Score()
{
int score = 0;
inti = 0;
{
// spare
if (rolls[i] + rolls[i + 1] == 10)
{
score += 10 + rolls[i + 2];
i += 2;
}
else
{
i += 2;
}
}
return score;
}
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
}

The Third test.
ugly comment in test.
ugly comment in conditional.
publicint Score()
{
int score = 0;
int roll = 0;
{
// spare
if (rolls[roll] + rolls[roll + 1] == 10)
{
score += 10 + rolls[roll + 2];
roll += 2;
}
else
{
score += rolls[roll] + rolls[roll + 1];
roll += 2;
}
}
return score;
}
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
}

The Third test.
publicint Score()
{
int score = 0;
int roll = 0;
{
if(IsSpare(roll))
{
roll += 2;
}
else
{
roll += 2;
}
}
returnscore;
}
privateboolIsSpare(int roll)
{
returnrolls[roll] +
rolls[roll + 1] == 10;
}
[Test]
{
g.Roll(5);
g.Roll(5); // spare
g.Roll(3);
RollMany(17, 0);
}

The Third test.
[Test]
{
RollSpare();
g.Roll(3);
RollMany(17, 0);
}
privatevoidRollSpare()
{
g.Roll(5);
g.Roll(5);
}
publicint Score()
{
int score = 0;
int roll = 0;
{
if(IsSpare(roll))
{
roll += 2;
}
else
{
roll += 2;
}
}
returnscore;
}
privateboolIsSpare(int roll)
{
returnrolls[roll] +
}

The Fourth test.
- ugly comment in OneStrikeTest.
[Test]
publicvoidOneStrikeTest()
{
g.Roll(10); // strike
g.Roll(3);
g.Roll(4);
RollMany(16, 0);
}
publicint Score()
{
int score = 0;
int roll = 0;
{
if(IsSpare(roll))
{
}
else
{
}
roll += 2;
}
returnscore;
}
privatebool IsSpare(int roll)
{
returnrolls[roll] +
}

The Fourth test.
ugly comment in OneStrikeTest.
ugly expressions.
publicint Score()
{
intscore = 0;
introll = 0;
for(int frame = 0; frame < 10; frame++)
{
if(rolls[roll] == 10) // strike
{
score += 10 + rolls[roll + 1]
+ rolls[roll + 2];
roll++;
}
elseif (IsSpare(roll))
{
roll += 2;
}
else
{
roll += 2;
}
}
returnscore;
}
[Test]
{
g.Roll(3);
g.Roll(4);
RollMany(16, 0);
}

The Fourth test.
ugly comment in OneStrikeTest.
publicint Score()
{
intscore = 0;
introll = 0;
for(int frame = 0; frame < 10; frame++)
{
if(rolls[roll] == 10) // strike
{
score += 10 + StrikeBonus(roll);
roll++;
}
{
score += 10 + SpareBonus(roll);
roll += 2;
}
else
{
score += SumOfBallsInFrame(roll);
roll += 2;
}
}
returnscore;
}
privateint SumOfBallsInFrame(int roll)
{
returnrolls[roll] + rolls[roll + 1];
}
privateint SpareBonus(int roll)
{
returnrolls[roll + 2];
}
privateint StrikeBonus(int roll)
{
returnrolls[roll + 1] + rolls[roll + 2];
}
[Test]
{
g.Roll(3);
g.Roll(4);
RollMany(16, 0);
}

The Fourth test.
- ugly comment in OneStrikeTest.
publicint Score()
{
int score = 0;
int roll = 0;
{
if(IsStrike(roll))
{
score += 10
+ StrikeBonus(roll);
roll++;
}
{
score += 10
+ SpareBonus(roll);
roll += 2;
}
else
{
roll += 2;
}
}
returnscore;
}
privatebool IsStrike(int roll)
{
returnrolls[roll] == 10;
}
[Test]
{
g.Roll(3);
g.Roll(4);
RollMany(16, 0);
}

The Fourth test.
[Test]
{
RollStrike();
g.Roll(3);
g.Roll(4);
RollMany(16, 0);
}
privatevoidRollStrike()
{
g.Roll(10);
}
publicint Score()
{
int score = 0;
int roll = 0;
{
if(IsStrike(roll))
{
score += 10
roll++;
}
{
score += 10
+ SpareBonus(roll);
roll += 2;
}
else
{
roll += 2;
}
}
returnscore;
}

The Fifth test.
[Test]
publicvoidPerfectGameTest()
{
RollMany(12, 10);
}
publicint Score()
{
int score = 0;
int roll = 0;
{
if(IsStrike(roll))
{
score += 10
roll++;
}
{
score += 10
+ SpareBonus(roll);
roll += 2;
}
else
{
roll += 2;
}
}
returnscore;
}

Discussion/Review

Adapted from:

http://blog.softwareontheside.com	401
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http://7414512759580466_9b3378270d5380bba828e28eee71721220422263.blogspot.com	4
http://theoldreader.com	3

Bowling Game Kata in C# Adapted

by Mike Clement

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