tests: add nibble_swap input filter test

test/02/t0269a.sh

@@ -0,0 +1,48 @@
+#!/bin/sh
+#
+#       srecord - manipulate eprom load files
+#       Copyright (C) 2023 fenugrec
+#
+#       This program is free software; you can redistribute it and/or modify
+#       it under the terms of the GNU General Public License as published by
+#       the Free Software Foundation; either version 3 of the License, or
+#       (at your option) any later version.
+#
+#       This program is distributed in the hope that it will be useful,
+#       but WITHOUT ANY WARRANTY; without even the implied warranty of
+#       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#       GNU General Public License for more details.
+#
+#       You should have received a copy of the GNU General Public License
+#       along with this program. If not, see
+#       <http://www.gnu.org/licenses/>.
+#
+
+TEST_SUBJECT="nibble swap filter"
+. test_prelude.sh
+
+cat > test.in << 'fubar'
+S00600004844521B
+S1070000F08008552B
+S5030001FB
+fubar
+if test $? -ne 0; then no_result; fi
+
+cat > test.ok << 'fubar'
+S00600004844521B
+S10700000F0880550C
+S5030001FB
+fubar
+if test $? -ne 0; then no_result; fi
+
+srec_cat test.in -ns -o test.out
+if test $? -ne 0; then fail; fi
+
+diff test.ok test.out
+if test $? -ne 0; then fail; fi
+
+#
+# The things tested here, worked.
+# No other guarantees are made.
+#
+pass