Automated Testing in Golang

librarian.go

package librarian

import (
	"time"
)

const (
	FINE_DAY   = 15
	FINE_MONTH = 500
	FINE_YEAR  = 10000
	NO_FINE    = 0
)

func CountFine(aD, eD time.Time) int {
	fine := NO_FINE

	// Actual Date
	adY := aD.Year()
	adM := int(aD.Month())
	adD := aD.Day()

	// Expected Date
	edY := eD.Year()
	edM := int(eD.Month())
	edD := eD.Day()

	if adY > edY {
		fine = FINE_YEAR
	} else if adM > edM && adY == edY {
		months := (adM - edM)
		if months > 0 {
			fine = months * FINE_MONTH
		}
	} else if adM == edM && adY == edY {
		days := (adD - edD)
		if days > 0 {
			fine = days * FINE_DAY
		}
	}

	return fine
}

librarian_test.go

package librarian

import (
	"fmt"
	"testing"
	"time"
)

type test struct {
	aD   time.Time
	eD   time.Time
	fine int
}

var tests = []test{
	{date(2015, time.June, 9), date(2015, time.June, 6), 45},
	{date(2015, time.June, 10), date(2015, time.June, 6), 60},
	{date(2015, time.July, 10), date(2015, time.June, 6), 500},
	{date(2015, time.August, 9), date(2015, time.June, 10), 1000},
	{date(2015, time.October, 10), date(2015, time.June, 6), 2000},
	{date(2016, time.July, 10), date(2015, time.June, 6), 10000},
	{date(2017, time.June, 9), date(2015, time.June, 6), 10000},
	{date(2015, time.November, 10), date(2015, time.June, 6), 2500},
	{date(2016, time.August, 10), date(2015, time.June, 6), 10000},
	{date(2015, time.June, 1), date(2015, time.June, 6), 0},
}

func date(y int, m time.Month, d int) time.Time {
	return time.Date(y, m, d, 0, 0, 0, 0, time.UTC)
}

func toString(d time.Time) string {
	return fmt.Sprintf(
		"%d-%s-%d",
		d.Year(),
		d.Month(),
		d.Day(),
	)
}

func TestCountFine(t *testing.T) {
	for _, test := range tests {
		fine := CountFine(test.aD, test.eD)
		if fine != test.fine {
			t.Error(
				"For `actual date` :", toString(test.aD),
				"and `expected date` :", toString(test.eD),
				"expected", test.fine,
				"got", fine,
			)
		}
	}
}