backend: Adjust tests to use the Factory to instantiate the backend

This drastically reduces the amount of duplicated test code.

internal/backend/rclone/backend_test.go

@@ -1,14 +1,11 @@
 package rclone_test
 
 import (
-	"context"
 	"os/exec"
 	"testing"
 
 	"github.com/restic/restic/internal/backend/rclone"
 	"github.com/restic/restic/internal/backend/test"
-	"github.com/restic/restic/internal/errors"
-	"github.com/restic/restic/internal/restic"
 	rtest "github.com/restic/restic/internal/test"
 )
 
@@ -24,23 +21,15 @@ func newTestSuite(t testing.TB) *test.Suite[rclone.Config] {
 			return &cfg, nil
 		},
 
-		// CreateFn is a function that creates a temporary repository for the tests.
-		Create: func(cfg rclone.Config) (restic.Backend, error) {
-			t.Logf("Create()")
-			be, err := rclone.Create(context.TODO(), cfg, nil)
-			var e *exec.Error
-			if errors.As(err, &e) && e.Err == exec.ErrNotFound {
-				t.Skipf("program %q not found", e.Name)
-				return nil, nil
-			}
-			return be, err
-		},
+		Factory: rclone.NewFactory(),
+	}
+}
 
-		// OpenFn is a function that opens a previously created temporary repository.
-		Open: func(cfg rclone.Config) (restic.Backend, error) {
-			t.Logf("Open()")
-			return rclone.Open(context.TODO(), cfg, nil)
-		},
+func findRclone(t testing.TB) {
+	// try to find a rclone binary
+	_, err := exec.LookPath("rclone")
+	if err != nil {
+		t.Skip(err)
 	}
 }
 
@@ -51,9 +40,11 @@ func TestBackendRclone(t *testing.T) {
 		}
 	}()
 
+	findRclone(t)
 	newTestSuite(t).RunTests(t)
 }
 
 func BenchmarkBackendREST(t *testing.B) {
+	findRclone(t)
 	newTestSuite(t).RunBenchmarks(t)
 }