things.go

package sqlmockthing

import (
	"database/sql"
	"log"
	"math/rand"
	"sync"
	"time"
)

type Thing struct {
	Name   string
	Number int
	Word   string
}

func GetThing(results chan Thing, db *sql.DB, name string, wg *sync.WaitGroup) {
	num := rand.Intn(100)
	log.Println(name, num)
	time.Sleep(time.Duration(num) * time.Millisecond)
	rows, err := db.Query("SELECT word FROM things WHERE number=?, name=?", num, name)
	if err != nil {
		log.Fatal(err)
	}
	for rows.Next() {
		var t Thing
		var word string
		if err := rows.Scan(&word); err != nil {
			log.Fatal(err)
		}
		t.Number = num
		t.Name = name
		t.Word = word
		results <- t
	}
}

func Words(db *sql.DB, names []string) (words map[string]string) {
	rand.Seed(time.Now().Unix())
	var wg sync.WaitGroup
	words = map[string]string{}
	results := make(chan Thing, len(names))
	defer close(results)
	for _, name := range names {
		wg.Add(1)
		go GetThing(results, db, name, &wg)
		go func(wg *sync.WaitGroup) {
			defer wg.Done()
			t := <-results
			words[t.Name] = t.Word
		}(&wg)
	}
	wg.Wait()
	return
}

things_test.go

package sqlmockthing

import (
	"gopkg.in/DATA-DOG/go-sqlmock.v1"
	"testing"
)

func TestShowWordsAndNumbers(t *testing.T) {
	db, mock, _ := sqlmock.New()
	defer db.Close()
	columns := []string{"word"}
	mock.ExpectQuery("SELECT word FROM things").WillReturnRows(
		sqlmock.NewRows(columns).AddRow("Fish"),
	)

	mock.ExpectQuery("SELECT word FROM things").WillReturnRows(
		sqlmock.NewRows(columns).AddRow("Bat"),
	)

	mock.ExpectQuery("SELECT word FROM things").WillReturnRows(
		sqlmock.NewRows(columns).AddRow("Horse"),
	)

	names := []string{"Fred", "Harry", "Billy"}
	words := Words(db, names)

	if words["Fred"] != "Fish" {
		t.Errorf("Fred's word is %s, should be Fish", words["Fred"])
	}
	if words["Billy"] != "Bat" {
		t.Errorf("Billy's word is %s, should be Bat", words["Billy"])
	}
	if words["Harry"] != "Horse" {
		t.Errorf("Harry's word is %s, should be Horse", words["Harry"])
	}
}