refactor: Simplify temp file creation in tests (#3290)

github/github_test.go

@@ -15,7 +15,7 @@ import (
 	"net/http/httptest"
 	"net/url"
 	"os"
-	"path"
+	"path/filepath"
 	"reflect"
 	"strconv"
 	"strings"
@@ -68,29 +68,23 @@ func setup() (client *Client, mux *http.ServeMux, serverURL string, teardown fun
 
 // openTestFile creates a new file with the given name and content for testing.
 // In order to ensure the exact file name, this function will create a new temp
-// directory, and create the file in that directory. It is the caller's
-// responsibility to remove the directory and its contents when no longer needed.
-func openTestFile(name, content string) (file *os.File, dir string, err error) {
-	dir, err = os.MkdirTemp("", "go-github")
+// directory, and create the file in that directory. The file is automatically
+// cleaned up after the test.
+func openTestFile(t *testing.T, name, content string) *os.File {
+	t.Helper()
+	fname := filepath.Join(t.TempDir(), name)
+	err := os.WriteFile(fname, []byte(content), 0600)
 	if err != nil {
-		return nil, dir, err
+		t.Fatal(err)
 	}
-
-	file, err = os.OpenFile(path.Join(dir, name), os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
+	file, err := os.Open(fname)
 	if err != nil {
-		return nil, dir, err
+		t.Fatal(err)
 	}
 
-	fmt.Fprint(file, content)
-
-	// close and re-open the file to keep file.Stat() happy
-	file.Close()
-	file, err = os.Open(file.Name())
-	if err != nil {
-		return nil, dir, err
-	}
+	t.Cleanup(func() { file.Close() })
 
-	return file, dir, err
+	return file
 }
 
 func testMethod(t *testing.T, r *http.Request, want string) {

github/repos_releases_test.go

@@ -12,7 +12,6 @@ import (
 	"fmt"
 	"io"
 	"net/http"
-	"os"
 	"strings"
 	"testing"
 
@@ -707,11 +706,7 @@ func TestRepositoriesService_UploadReleaseAsset(t *testing.T) {
 			fmt.Fprintf(w, `{"id":1}`)
 		})
 
-		file, dir, err := openTestFile(test.fileName, "Upload me !\n")
-		if err != nil {
-			t.Fatalf("Unable to create temp file: %v", err)
-		}
-		defer os.RemoveAll(dir)
+		file := openTestFile(t, test.fileName, "Upload me !\n")
 
 		ctx := context.Background()
 		asset, _, err := client.Repositories.UploadReleaseAsset(ctx, "o", "r", int64(key), test.uploadOpts, file)