fizzbuzz-tdd-golang.go

package main

import "strconv"

//solveFizzBuzz solves Fizzbuzz algorithm with given rules below :
//https://en.wikipedia.org/wiki/Fizz_buzz
//Count incrementally up to n :
//when a number is divisible by 3 replace it with Fizz
//when its divisible by 5 replace it with Buzz
//when its divisible by 5 AND 3 replace it with FizzBuzz
func solveFizzBuzz(puzzleLength int) string {
	return decodeEachFizzBuzzNumber(puzzleLength, "")
}

func decodeEachFizzBuzzNumber(currentNumber int, solution string) string {
	if currentNumber == 0 {
		return solution
	}
	decodedNumber := decodeFizzBuzzNumber(currentNumber)
	return decodeEachFizzBuzzNumber(currentNumber - 1, decodedNumber+solution)
}

func decodeFizzBuzzNumber(n int) string {
	if isDivisibleByThree(n) && isDivisibleByFive(n) {
		return "FizzBuzz"
	}
	if isDivisibleByThree(n) {
		return "Fizz"
	}
	if isDivisibleByFive(n) {
		return "Buzz"
	}
	return strconv.Itoa(n)
}

func isDivisibleByThree(n int) bool {
	return areNumbersDivisible(n, 3)
}

func isDivisibleByFive(n int) bool {
	return areNumbersDivisible(n, 5)
}

func areNumbersDivisible(source int, n int) bool {
	return source % n == 0
}

fizzbuzz-tdd-golang_test.go

package main

import (
	"github.com/stretchr/testify/assert"
	"testing"
)

func TestSolveFizzBuzz(t *testing.T) {
	var tests = []struct{
		inputPuzzleLength int
		outputSolution string
	}{
		{
			inputPuzzleLength: 1,
			outputSolution: "1",
		},
		{
			inputPuzzleLength: 2,
			outputSolution: "12",
		},
		{
			inputPuzzleLength: 3,
			outputSolution: "12Fizz",
		},
		{
			inputPuzzleLength: 4,
			outputSolution: "12Fizz4",
		},
		{
			inputPuzzleLength: 5,
			outputSolution: "12Fizz4Buzz",
		},
		{
			inputPuzzleLength: 6,
			outputSolution: "12Fizz4BuzzFizz",
		},
		{
			inputPuzzleLength: 7,
			outputSolution: "12Fizz4BuzzFizz7",
		},
		{
			inputPuzzleLength: 8,
			outputSolution: "12Fizz4BuzzFizz78",
		},
		{
			inputPuzzleLength: 9,
			outputSolution: "12Fizz4BuzzFizz78Fizz",
		},
		{
			inputPuzzleLength: 10,
			outputSolution: "12Fizz4BuzzFizz78FizzBuzz",
		},
		{
			inputPuzzleLength: 11,
			outputSolution: "12Fizz4BuzzFizz78FizzBuzz11",
		},
		{
			inputPuzzleLength: 12,
			outputSolution: "12Fizz4BuzzFizz78FizzBuzz11Fizz",
		},
		{
			inputPuzzleLength: 13,
			outputSolution: "12Fizz4BuzzFizz78FizzBuzz11Fizz13",
		},
		{
			inputPuzzleLength: 15,
			outputSolution: "12Fizz4BuzzFizz78FizzBuzz11Fizz1314FizzBuzz",
		},
	}

	for _, test := range tests {
		solution := solveFizzBuzz(test.inputPuzzleLength)
		assert.Equal(t, test.outputSolution, solution)
	}
}