fstest: implement method to skip ChunkedCopy tests

fstest/fstests/fstests.go

@@ -83,6 +83,7 @@ type SetUploadCutoffer interface {
 type SetCopyCutoffer interface {
 	// Change the configured CopyCutoff.
 	// Will only be called while no transfer is in progress.
+	// Return fs.ErrorNotImplemented if you can't implement this
 	SetCopyCutoff(fs.SizeSuffix) (fs.SizeSuffix, error)
 }
 
@@ -2345,10 +2346,6 @@ func Run(t *testing.T, opt *Opt) {
 				t.Skip("skipping as ChunkedUpload.Skip is set")
 			}
 
-			if strings.HasPrefix(f.Name(), "serves3") || strings.HasPrefix(f.Name(), "TestS3Rclone") {
-				t.Skip("FIXME skip test - see #7454")
-			}
-
 			do, _ := f.(SetCopyCutoffer)
 			if do == nil {
 				t.Skipf("%T does not implement SetCopyCutoff", f)
@@ -2362,6 +2359,13 @@ func Run(t *testing.T, opt *Opt) {
 				minChunkSize = opt.ChunkedUpload.CeilChunkSize(minChunkSize)
 			}
 
+			// Test setting the copy cutoff before we get going
+			_, err := do.SetCopyCutoff(minChunkSize)
+			if errors.Is(err, fs.ErrorNotImplemented) {
+				t.Skipf("%T does not support SetCopyCutoff: %v", f, err)
+			}
+			require.NoError(t, err)
+
 			chunkSizes := fs.SizeSuffixList{
 				minChunkSize,
 				minChunkSize + 1,