fstest: let backends advertise maximum file size

fs/operations/multithread_test.go

@@ -115,6 +115,9 @@ func TestMultithreadCopy(t *testing.T) {
 		{size: multithreadChunkSize*2 + 1, streams: 2},
 	} {
 		t.Run(fmt.Sprintf("%+v", test), func(t *testing.T) {
+			if *fstest.SizeLimit > 0 && int64(test.size) > *fstest.SizeLimit {
+				t.Skipf("exceeded file size limit %d > %d", test.size, *fstest.SizeLimit)
+			}
 			var err error
 			contents := random.String(test.size)
 			t1 := fstest.Time("2001-02-03T04:05:06.499999999Z")

fs/operations/operations_test.go

@@ -445,6 +445,15 @@ func TestRcat(t *testing.T) {
 		r := fstest.NewRun(t)
 		defer r.Finalise()
 
+		if *fstest.SizeLimit > 0 && int64(fs.Config.StreamingUploadCutoff) > *fstest.SizeLimit {
+			savedCutoff := fs.Config.StreamingUploadCutoff
+			defer func() {
+				fs.Config.StreamingUploadCutoff = savedCutoff
+			}()
+			fs.Config.StreamingUploadCutoff = fs.SizeSuffix(*fstest.SizeLimit)
+			t.Logf("Adjust StreamingUploadCutoff to size limit %s (was %s)", fs.Config.StreamingUploadCutoff, savedCutoff)
+		}
+
 		fstest.CheckListing(t, r.Fremote, []fstest.Item{})
 
 		data1 := "this is some really nice test data"