Apply go fix -rangeint ./...

internal/backend/cache/backend_test.go

@@ -238,7 +238,7 @@ func TestErrorBackend(t *testing.T) {
 
 	wrappedBE := c.Wrap(errBackend, t.Logf)
 	var wg sync.WaitGroup
-	for i := 0; i < 5; i++ {
+	for range 5 {
 		wg.Add(1)
 		go loadTest(&wg, wrappedBE)
 	}

internal/backend/cache/cache_test.go

@@ -24,7 +24,7 @@ func TestNew(t *testing.T) {
 		stepEnd
 	)
 
-	for step := stepCreate; step < stepEnd; step++ {
+	for step := range stepEnd {
 		switch step {
 		case stepRmTag:
 			rtest.OK(t, os.Remove(tagFile))

internal/backend/cache/file_test.go

@@ -243,7 +243,7 @@ func TestFileSaveConcurrent(t *testing.T) {
 		Name: id.String(),
 	}
 
-	for i := 0; i < nproc/2; i++ {
+	for range nproc / 2 {
 		g.Go(func() error { return c.save(h, bytes.NewReader(data)) })
 
 		// Can't use load because only the main goroutine may call t.Fatal.