counter/counter.go

@@ -1,22 +0,0 @@
-package counter
-
-import "sync"
-
-type Counter struct {
-	count int
-	mutex sync.Mutex
-}
-
-func NewCounter() *Counter {
-	return &Counter{}
-}
-
-func (c *Counter) Inc() {
-	c.mutex.Lock()
-	defer c.mutex.Unlock()
-	c.count++
-}
-
-func (c *Counter) Value() int {
-	return c.count
-}

counter/counter_test.go

@@ -1,44 +0,0 @@
-package counter
-
-import (
-	"sync"
-	"testing"
-)
-
-// assertCounter
-// XXX: a copy of Counter is created, but we shouldn't copy a mutex. Use pointer instead.
-func assertCounter(t testing.TB, got *Counter, want int) {
-	t.Helper()
-	if got.Value() != want {
-		t.Errorf("got %d, want %d", got.Value(), want)
-	}
-}
-
-func TestCounter(t *testing.T) {
-	t.Run("incrementing the counter 3 times leaves it at 3", func(t *testing.T) {
-		counter := NewCounter()
-
-		counter.Inc()
-		counter.Inc()
-		counter.Inc()
-
-		assertCounter(t, counter, 3)
-	})
-
-	t.Run("it runs safely concurrently", func(t *testing.T) {
-		wantedCount := 1000
-		counter := NewCounter()
-
-		var wg sync.WaitGroup
-		wg.Add(wantedCount)
-
-		for i := 0; i < wantedCount; i++ {
-			go func() {
-				counter.Inc()
-				wg.Done()
-			}()
-		}
-		wg.Wait()
-		assertCounter(t, counter, wantedCount)
-	})
-}