tests: removed POSIX testing (fixes #163)

tests/swab.mk

@@ -0,0 +1,22 @@
+# Copyright (c) 2024 DTB <trinity@trinity.moe>
+# SPDX-License-Identifier: FSFAP
+#
+# Copying and distribution of this file, with or without modification, are
+# permitted in any medium without royalty provided the copyright notice and this
+# notice are preserved.  This file is offered as-is, without any warranty.
+
+.PRAGMA: command_comment
+
+.PHONY: swab_tests
+swab_tests: swab_help swab_examples
+
+.PHONY: swab_help
+swab_help: $(BIN)/swab
+	! $(BIN)/swab -h
+
+.PHONY: swab_examples
+# These are the examples present in the man page.
+swab_examples: $(BIN)/swab
+	printf 'hello world!\n' \
+		| $(BIN)/swab \
+		| xargs -I out test 'ehll oowlr!d' = out