Tests: Cleanup: Remove unused test_external[_without_stderr]()

These make sense in the original context of testing Git commands (that may have external test scripts), but for todo.sh we've never used them, nor are they likely to be useful for this project.

tests/test-lib.sh

@@ -316,64 +316,6 @@ expected exit code $1, actual ${eval_ret}"
 	echo >&3 ""
 }
 
-# test_external runs external test scripts that provide continuous
-# test output about their progress, and succeeds/fails on
-# zero/non-zero exit code.  It outputs the test output on stdout even
-# in non-verbose mode, and announces the external script with "* run
-# <n>: ..." before running it.  When providing relative paths, keep in
-# mind that all scripts run in "trash directory".
-# Usage: test_external description command arguments...
-# Example: test_external 'Perl API' perl ../path/to/test.pl
-test_external () {
-	test "$#" -eq 3 ||
-	error >&5 "bug in the test script: not 3 parameters to test_external"
-	descr="$1"
-	shift
-	if ! test_skip "$descr" "$@"
-	then
-		# Announce the script to reduce confusion about the
-		# test output that follows.
-		say_color "" " run $test_count: $descr ($*)"
-		# Run command; redirect its stderr to &4 as in
-		# test_run_, but keep its stdout on our stdout even in
-		# non-verbose mode.
-		"$@" 2>&4
-		if [ "$?" = 0 ]
-		then
-			test_ok_ "$descr"
-		else
-			test_failure_ "$descr" "$@"
-		fi
-	fi
-}
-
-# Like test_external, but in addition tests that the command generated
-# no output on stderr.
-test_external_without_stderr () {
-	# The temporary file has no (and must have no) security
-	# implications.
-	tmp="$TMPDIR"; if [ -z "$tmp" ]; then tmp=/tmp; fi
-	stderr="$tmp/todotxt-external-stderr.$$.tmp"
-	test_external "$@" 4> "$stderr"
-	[ -f "$stderr" ] || error "Internal error: $stderr disappeared."
-	descr="no stderr: $1"
-	shift
-	say >&3 "expecting no stderr from previous command"
-	if [ ! -s "$stderr" ]; then
-		rm "$stderr"
-		test_ok_ "$descr"
-	else
-		if [ "$verbose" = t ]; then
-			output=$(echo; echo Stderr is:; cat "$stderr")
-		else
-			output=
-		fi
-		# rm first in case test_failure exits.
-		rm "$stderr"
-		test_failure_ "$descr" "$@" "$output"
-	fi
-}
-
 # This is not among top-level (test_expect_success | test_expect_failure)
 # but is a prefix that can be used in the test script, like:
 #