Use t.TempDir() to access a guaranteed writable directory.

This is available since [Go 1.15](https://tip.golang.org/doc/go1.15#testingpkgtesting).

Author: happygiraffe

roaring64/bsi64_test.go

@@ -644,11 +644,10 @@ func TestMinMaxWithNilFoundSet(t *testing.T) {
 }
 
 func TestBSIWriteToReadFrom(t *testing.T) {
-	file, err := os.CreateTemp("./testdata", "bsi-test")
+	file, err := os.CreateTemp(t.TempDir(), "bsi-test")
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer t.Cleanup(func() { os.Remove(file.Name()) })
 	defer file.Close()
 	bsi, min, max := setupRandom()
 	_, err = bsi.WriteTo(file)

roaring64/serialization_test.go

@@ -86,7 +86,7 @@ func TestSerializationBasic037(t *testing.T) {
 
 func TestSerializationToFile038(t *testing.T) {
 	rb := BitmapOf(1, 2, 3, 4, 5, 100, 1000)
-	fname := "myfile.bin"
+	fname := filepath.Join(t.TempDir(), "myfile.bin")
 	fout, err := os.OpenFile(fname, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0o660)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "\n\nIMPORTANT: For testing file IO, the roaring library requires disk access.\nWe omit some tests for now.\n\n")
@@ -113,10 +113,7 @@ func TestSerializationToFile038(t *testing.T) {
 	buf := bytes.NewBuffer(nil)
 	teer := io.TeeReader(fin, buf)
 
-	defer func() {
-		fin.Close()
-		_ = os.Remove(fname)
-	}()
+	defer 		fin.Close()
 
 	_, _ = newrb.ReadFrom(teer)
 	assert.True(t, rb.Equals(newrb))

serialization_test.go

@@ -64,7 +64,7 @@ func TestSerializationBasic037(t *testing.T) {
 
 func TestSerializationToFile038(t *testing.T) {
 	rb := BitmapOf(1, 2, 3, 4, 5, 100, 1000)
-	fname := "myfile.bin"
+	fname := filepath.Join(t.TempDir(), "myfile.bin")
 	fout, err := os.OpenFile(fname, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0660)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "\n\nIMPORTANT: For testing file IO, the roaring library requires disk access.\nWe omit some tests for now.\n\n")
@@ -89,10 +89,7 @@ func TestSerializationToFile038(t *testing.T) {
 		return
 	}
 
-	defer func() {
-		fin.Close()
-		_ = os.Remove(fname)
-	}()
+	defer fin.Close()
 
 	_, _ = newrb.ReadFrom(fin)
 	assert.True(t, rb.Equals(newrb))