diff --git a/Makefile b/Makefile
index f181e20..494f0f7 100644
--- a/Makefile
+++ b/Makefile
@@ -14,6 +14,7 @@
PREFIX=/usr/local
CC=cc
+MAKE=make
RUSTC=rustc
.PHONY: all
@@ -42,6 +43,7 @@ install: dist
test: build
tests/posix-compat.sh
$(RUSTC) --test src/getopt-rs/lib.rs -o build/test/getopt
+ $(MAKE) -f Testfile
build/o/libsysexits.rlib: build
# bandage solution until bindgen(1) gets stdin support
diff --git a/TESTING b/TESTING
deleted file mode 100755
index 2f92ece..0000000
--- a/TESTING
+++ /dev/null
@@ -1,74 +0,0 @@
-#!/bin/sh
-
-### Overview
-#
-# Testing is conducted with this script, in the source tree root, using the
-# tests in tests/.
-#
-# Basically, tests follow the format:
-#
-# - tests/[utility].[number].test
-# Test #[number]. This is an executable file (typically a script).
-# - tests/[utility].[number].expected
-# This is the expected standard output of test #[number].
-#
-# This script runs the executable [utility].[number].test and the following
-# file is written during testing:
-#
-# - tests/[utility].[number].output
-# The actual standard output from test #[number].
-#
-# If the actual standard output from the test differs from the expected
-# standard output, the testing ends, showing the difference.
-
-set -e
-
-alias emit="printf '%s: %s\n' '$0' \"\$1\""
-
-export PATH="$PATH:./build/bin/"
-
-if strcmp '' "$1"; then
- printf 'Usage: %s [utilities...]\n' "$0" >&2
- exit 64 # sysexits.h(3) EX_USAGE
-fi
-
-### Details
-
-while ! strcmp '' "$1"; do # $1 refers to the given utility
-
-# Tests are called [utility].[number].test. Tests are numbered from 1 with no
-# leading zeroes in the numbers, so (for example) scrut(1)'s first three tests
-# are scrut.1.test, scrut.2.test, and scrut.3.test. Tests are run sequentially
-# in the numbered order.
-
- i=1
- while scrut -e "$1.$i.test"; do # $i refers to the test number
- emit "$1.$i.test: Running test..."
-
-# A test is an executable file. This runs each test for given utilities
-# and writes the standard output from the test to [utility].[number].output,
-# then uses diff(1p) (with the "-u" option) to highlight differences between
-# the actual output and the expected output, which is located at
-# [utility].[number].expected. If there are no differences none are shown and
-# testing continues.
-
- # $1.$i.test is the same as [utility].[number].test
- ./"$1.$i.test" \
- | mm -o "$1.$i.output" -o - \
- | diff -u - "$1.$i.expected" \
- || emit '$1.$i.test: Test passed.\n'
- # "set -e" terminates on an unsuccessful exit
-
-# The ideal output of this script is no output at all and each
-# [utility].[number].output written matching its associated
-# [utility].[number].expected.
-
- i=$(rpn 1 "$i" +)
- done
-
- shift
-done
-
-# --
-# This work © 2024 by DTB is licensed under CC BY-SA 4.0. To view a copy of
-# this license, visit
diff --git a/Testfile b/Testfile
new file mode 100755
index 0000000..6b0ed42
--- /dev/null
+++ b/Testfile
@@ -0,0 +1,77 @@
+# Copyright (c) 2024 DTB
+# 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.
+
+BIN = build/bin
+MAKE = make -B
+
+DEFENDANTS = dj false intcmp strcmp true
+.PHONY: all $(DEFENDANTS)
+all: $(DEFENDANTS)
+
+$(BIN)/dj:
+ $(MAKE) dj
+
+$(BIN)/false:
+ $(MAKE) false
+
+$(BIN)/intcmp:
+ $(MAKE) intcmp
+
+$(BIN)/strcmp
+ $(MAKE) strcmp
+
+$(BIN)/true:
+ $(MAKE) true
+
+dj: $(BIN)/dj $(BIN)/strcmp
+ sh -c "! $(BIN)/dj -h"
+ # This test is theoretically Linux-dependent; write(2) should return -1 on
+ # error.
+ # Right now dj(1) interprets the return value of write(2) as the amount of
+ # bytes written. This can decrement the stored quantity of bytes written,
+ # which is an int, so doesn't underflow but goes negative. dj(1) tries to
+ # again to write(2) if an error occurs in which no bytes are written, so in
+ # total two write(2)s are attempted and so the written byte quantity is -2.
+ # This is a bug and will change, but for now is at least documented.
+ sh -ec "\
+ $(BIN)/dj -Hi /dev/zero -o /dev/full \
+ | xargs -I out $(BIN)/strcmp '1+0 > 0+0; 1024 > -2' out"
+ # Read nothing from /dev/null, write nothing to /dev/null.
+ sh -ec "\
+ $(BIN)/dj -Hi /dev/null -o /dev/null \
+ | xargs -I out $(BIN)/strcmp '0+0 > 0+0; 0 > 0' out"
+
+false: $(BIN)/false
+ sh -c "! $(BIN)/false"
+ sh -c "! $(BIN)/false -h"
+
+intcmp: $(BIN)/intcmp
+ intcmp -e 3 3 3
+ intcmp -g 3 2 1
+ intcmp -l 1 2 3
+ intcmp -ge 3 3 1
+ intcmp -le 1 3 3
+ intcmp -gl 1 2 3
+ intcmp -egl 3 1 1 2
+ sh -c "! intcmp -e 1 2 3"
+ sh -c "! intcmp -g 1 3 3"
+ sh -c "! intcmp -l 3 3 1"
+ sh -c "! intcmp -ge 1 2 3"
+ sh -c "! intcmp -le 3 2 1"
+ sh -c "! intcmp -gl 3 3 3"
+ sh -c "! intcmp -egl foo"
+
+strcmp: $(BIN)/strcmp
+ $(BIN)/strcmp equals equals
+ sh -c "! $(BIN)/strcmp inequals equals"
+ $(BIN)/strcmp - -
+ sh -c "! $(BIN)/strcmp -h"
+ sh -c "! $(BIN)/strcmp nocmp"
+
+true:
+ $(BIN)/true
+ $(BIN)/true -h