r, idxCB := newS2CompressReader(bytes.NewReader(tt.data), int64(len(tt.data)), false)
			defer r.Close()

			var rdrBuf bytes.Buffer
			_, err := io.CopyBuffer(&rdrBuf, r, buf)
			if err != nil {
				t.Fatal(err)
			}
			r.Close()
			idx := idxCB()
			if !tt.wantIdx && len(idx) > 0 {
				t.Errorf("index returned above threshold")
			}
			if tt.wantIdx {

		if err != nil {
			return err
		}
		// Check if we have a response ready or a filler byte.
		switch tmp[0] {
		case 0:
			// 0 is unbuffered, copy the rest.
			_, err := io.CopyBuffer(w, respBody, buf)
			if err == io.EOF {
				return nil
			}
			return err
		case 1:
			errorText, err := io.ReadAll(respBody)
			if err != nil {
				return err
			}