Prime Factors Kata (1)

7/21/2019 Prime Factors Kata (1)

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Prime Factors Kata

Object Mentor, Inc.

fitnesse.org

Copyright 2005 by Object Mentor, Inc

All copies must retain this page unchanged.

www.junit.org

www.objectmentor.com

blog.objectmentor.com


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Generating Prime Factors.

Although quite short, this kata is fascinating in the wa it shows how !if" statements

become !while" statements as the number of test cases increase. It"s also a

won#erful e$am%le of how algorithms sometimes become sim%ler as the become

more general.

I stumble# u%on this little kata one e&ening when m son was in 'thgra#e. (e

ha# just #isco&ere# that all numbers can be broken #own into a %ro#uct of %rimes

an# was intereste# in e$%loring this further. )o I wrote a little rub %rogram, test*

first, an# was stunne# b how the algorithm e&ol&e#.

I ha&e #one this %articular kata in +a&a .-. his shoul# gi&e ou a feel for the

%ower an# con&enience of some of the new features.


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he /equirements.

0 g e n e r a t e 1 n 2 i n t 3

P r i m e F a c t o r s

4 5rite a class name# 6PrimeFactors7 that

has one static metho#2 generate.8 he generate metho# takes an integer

argument an# returns a 9ist:Integer;. hat

list contains the %rime factors in numerical

sequence.


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he first test.package primeFactors;

import junit.framework.TestCase;

public class PrimeFactorsTest extends TestCase {

public void testne!" t#rows $xception {

assert$%uals!list!"&PrimeFactors.generate!'"";

}

}


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import java.util.(ist;




}

private (ist)*nteger+ list!" {

return null;

}}


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}


return null;

}}

package primeFactors;

public class PrimeFactors {

}


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}


return null;

}}


import java.util.,;


public static (ist)*nteger+ generate!int n" {

return new -rra(ist)*nteger+!";

}

}

expected: but was:


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import java.util.,;




}



}}


import java.util.,;




}

}


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import java.util.,;




}



}}


import java.util.,;




}

}


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he )econ# est


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he )econ# test.package primeFactors;


import java.util.,;




}



}

public void testTwo!" t#rows $xception {

assert$%uals!list!/"&PrimeFactors.generate!/"";

}

}


import java.util.,;




}

}


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import java.util.,;


private (ist)*nteger+ list!int... ints" {

(ist)*nteger+ list 0new -rra(ist)*nteger+!";

for !int i 1 ints"

list.add!i";

return list;

}



}



}

}


import java.util.,;




}

}

varargs

expected: but was:


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import java.util.,;



(ist)*nteger+ list 0 new -rra(ist)*nteger+!";

for !int i 1 ints"

list.add!i";

return list;

}



}



}

}


import java.util.,;



(ist)*nteger+ primes 0 new -rra(ist)*nteger+!";

if !n + '" {

primes.add!/";

}

return primes;

}

}


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import static primeFactors.PrimeFactors.generate;


import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}


assert$%uals!list!"&generate!'"";

}


assert$%uals!list!/"&generate!/"";

}

}


import java.util.,;




if !n + '" {

primes.add!/";

}

return primes;

}

}


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he hir# est


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he hir# test.package primeFactors;



import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}

public void testT#ree!" t#rows $xception {

assert$%uals!list!2"&generate!2"";

}

}


import java.util.,;




if !n + '" {

primes.add!/";

}

return primes;

}

}

expected: but was:


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he hir# test.package primeFactors;



import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}

}


import java.util.,;




if !n + '" {

primes.add!n";

}

return primes;

}

}


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he Fourth est


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he Fourth test.package primeFactors;



import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}

public void testFour!" t#rows $xception {

assert$%uals!list!/&/"&generate!3"";

}

}


import java.util.,;




if !n + '" {

primes.add!n";

}

return primes;

}

}

expected: but was:


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he Fourth test.package primeFactors;



import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}

}


import java.util.,;




if !n + '" {

if !n4/ 00 5" {

primes.add!/";

n 60 /;

}

if !n + '"

primes.add!n"; }

return primes;

}

}


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he Fifth est


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he Fifth test.package primeFactors;



import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}

public void test7ix!" t#rows $xception {

assert$%uals!list!/&2"&generate!8"";

}

}


import java.util.,;




if !n + '" {

if !n4/ 00 5" {

primes.add!/";

n 60 /;

}

if !n + '"

primes.add!n"; }

return primes;

}

}


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he )i$th est


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he )i$th test.package primeFactors;



import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}



}

public void test$ig#t!" t#rows $xception {

assert$%uals!list!/&/&/"&generate!9"";

}

}


import java.util.,;




if !n + '" {

if !n4/ 00 5" {

primes.add!/";

n 60 /;

}

if !n + '"

primes.add!n"; }

return primes;

}

}

expected: but was:


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he )i$th test.package primeFactors;



import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}



}



}

}


import java.util.,;




if !n + '" {

w#ile!n4/ 00 5" {

primes.add!/";

n 60 /;

}

if !n + '"

primes.add!n"; }

return primes;

}

}

! ! !


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he )e&enth est


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he )e&enth test.package primeFactors;import static primeFactors.PrimeFactors.generate;


import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}

public void test7ix!" t#rows $xception { assert$%uals!list!/&2"&generate!8"";

}



}

public void test:ine!" t#rows $xception {

assert$%uals!list!2&2"&generate!"";

}

}


import java.util.,;




if !n + '" {

w#ile !n4/ 00 5" {

primes.add!/";

n 60 /;

}

if !n + '"

primes.add!n";

}

return primes;

}

}

expected: but was:


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import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}


}



}



}

}


import java.util.,;




if !n + '" {

int candidate 0 /;

w#ile !n4candidate00 5" {

primes.add!candidate";

n 60 candidate;

}

if !n + '"

primes.add!n";

}

return primes;

}

}

expected: but was:


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import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}


}



}



}

}


import java.util.,;




if !n + '" {

int candidate 0 /;

w#ile !n 4 candidate 00 5" {


n 60 candidate;

}

}

if !n + '"

primes.add!n";

return primes;

}

}

expected: but was:


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import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}


}



}



}

}


import java.util.,;




int candidate 0 /;

if !n + '" {



n 60 candidate;

}

}

if !n + '"

primes.add!n";

return primes;

}

}

expected: but was:


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import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}


}



}



}

}


import java.util.,;




int candidate 0 /;

if !n + '" {



n 60 candidate;

}

}

if !n + '"

primes.add!n";

return primes;

}

}

expected: but was:


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import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}


}



}



}

}


import java.util.,;




int candidate 0 /;

w#ile!n + '" {



n 60 candidate;

}

candidate


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import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}


}



}



}

}


import java.util.,;




int candidate 0 /;

w#ile !n + '" {



n 60 candidate;

}

candidate


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import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}


}



}



}

}


import java.util.,;




int candidate 0 /;

w#ile !n + '" {

for!; n4candidate 00 5; n60candidate"


candidate


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import java.util.,;




for !int i 1 ints"

list.add!i";

return list;

}



}



}



}



}


}



}



}

}


import java.util.,;




for !int candidate 0 /; n + '; candidate


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Prime Factors Kata (1)