diff --git a/assert.sh b/assert.sh
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+#!/bin/bash
+# assert.sh 1.1 - bash unit testing framework
+# Copyright (C) 2009-2015 Robert Lehmann
+#
+# http://github.com/lehmannro/assert.sh
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+export DISCOVERONLY=${DISCOVERONLY:-}
+export DEBUG=${DEBUG:-}
+export STOP=${STOP:-}
+export INVARIANT=${INVARIANT:-}
+export CONTINUE=${CONTINUE:-}
+
+args="$(getopt -n "$0" -l \
+    verbose,help,stop,discover,invariant,continue vhxdic $*)" \
+|| exit -1
+for arg in $args; do
+    case "$arg" in
+        -h)
+            echo "$0 [-vxidc]" \
+                "[--verbose] [--stop] [--invariant] [--discover] [--continue]"
+            echo "`sed 's/./ /g' <<< "$0"` [-h] [--help]"
+            exit 0;;
+        --help)
+            cat <<EOF
+Usage: $0 [options]
+Language-agnostic unit tests for subprocesses.
+
+Options:
+  -v, --verbose    generate output for every individual test case
+  -x, --stop       stop running tests after the first failure
+  -i, --invariant  do not measure timings to remain invariant between runs
+  -d, --discover   collect test suites only, do not run any tests
+  -c, --continue   do not modify exit code to test suite status
+  -h               show brief usage information and exit
+  --help           show this help message and exit
+EOF
+            exit 0;;
+        -v|--verbose)
+            DEBUG=1;;
+        -x|--stop)
+            STOP=1;;
+        -i|--invariant)
+            INVARIANT=1;;
+        -d|--discover)
+            DISCOVERONLY=1;;
+        -c|--continue)
+            CONTINUE=1;;
+    esac
+done
+
+_indent=$'\n\t' # local format helper
+
+_assert_reset() {
+    tests_ran=0
+    tests_failed=0
+    tests_errors=()
+    tests_starttime="$(date +%s%N)" # nanoseconds_since_epoch
+}
+
+assert_end() {
+    # assert_end [suite ..]
+    tests_endtime="$(date +%s%N)"
+    # required visible decimal place for seconds (leading zeros if needed)
+    local tests_time="$( \
+        printf "%010d" "$(( ${tests_endtime/%N/000000000} 
+                            - ${tests_starttime/%N/000000000} ))")"  # in ns
+    tests="$tests_ran ${*:+$* }tests"
+    [[ -n "$DISCOVERONLY" ]] && echo "collected $tests." && _assert_reset && return
+    [[ -n "$DEBUG" ]] && echo
+    # to get report_time split tests_time on 2 substrings:
+    #   ${tests_time:0:${#tests_time}-9} - seconds
+    #   ${tests_time:${#tests_time}-9:3} - milliseconds
+    [[ -z "$INVARIANT" ]] \
+        && report_time=" in ${tests_time:0:${#tests_time}-9}.${tests_time:${#tests_time}-9:3}s" \
+        || report_time=
+
+    if [[ "$tests_failed" -eq 0 ]]; then
+        echo "all $tests passed$report_time."
+    else
+        for error in "${tests_errors[@]}"; do echo "$error"; done
+        echo "$tests_failed of $tests failed$report_time."
+    fi
+    tests_failed_previous=$tests_failed
+    [[ $tests_failed -gt 0 ]] && tests_suite_status=1
+    _assert_reset
+}
+
+assert() {
+    # assert <command> <expected stdout> [stdin]
+    (( tests_ran++ )) || :
+    [[ -z "$DISCOVERONLY" ]] || return
+    expected=$(echo -ne "${2:-}")
+    result="$(eval 2>/dev/null $1 <<< ${3:-})" || true
+    if [[ "$result" == "$expected" ]]; then
+        [[ -z "$DEBUG" ]] || echo -n .
+        return
+    fi
+    result="$(sed -e :a -e '$!N;s/\n/\\n/;ta' <<< "$result")"
+    [[ -z "$result" ]] && result="nothing" || result="\"$result\""
+    [[ -z "$2" ]] && expected="nothing" || expected="\"$2\""
+    _assert_fail "expected $expected${_indent}got $result" "$1" "$3"
+}
+
+assert_raises() {
+    # assert_raises <command> <expected code> [stdin]
+    (( tests_ran++ )) || :
+    [[ -z "$DISCOVERONLY" ]] || return
+    status=0
+    (eval $1 <<< ${3:-}) > /dev/null 2>&1 || status=$?
+    expected=${2:-0}
+    if [[ "$status" -eq "$expected" ]]; then
+        [[ -z "$DEBUG" ]] || echo -n .
+        return
+    fi
+    _assert_fail "program terminated with code $status instead of $expected" "$1" "$3"
+}
+
+_assert_fail() {
+    # _assert_fail <failure> <command> <stdin>
+    [[ -n "$DEBUG" ]] && echo -n X
+    report="test #$tests_ran \"$2${3:+ <<< $3}\" failed:${_indent}$1"
+    if [[ -n "$STOP" ]]; then
+        [[ -n "$DEBUG" ]] && echo
+        echo "$report"
+        exit 1
+    fi
+    tests_errors[$tests_failed]="$report"
+    (( tests_failed++ )) || :
+}
+
+skip_if() {
+    # skip_if <command ..>
+    (eval $@) > /dev/null 2>&1 && status=0 || status=$?
+    [[ "$status" -eq 0 ]] || return
+    skip
+}
+
+skip() {
+    # skip  (no arguments)
+    shopt -q extdebug && tests_extdebug=0 || tests_extdebug=1
+    shopt -q -o errexit && tests_errexit=0 || tests_errexit=1
+    # enable extdebug so returning 1 in a DEBUG trap handler skips next command
+    shopt -s extdebug
+    # disable errexit (set -e) so we can safely return 1 without causing exit
+    set +o errexit
+    tests_trapped=0
+    trap _skip DEBUG
+}
+_skip() {
+    if [[ $tests_trapped -eq 0 ]]; then
+        # DEBUG trap for command we want to skip.  Do not remove the handler
+        # yet because *after* the command we need to reset extdebug/errexit (in
+        # another DEBUG trap.)
+        tests_trapped=1
+        [[ -z "$DEBUG" ]] || echo -n s
+        return 1
+    else
+        trap - DEBUG
+        [[ $tests_extdebug -eq 0 ]] || shopt -u extdebug
+        [[ $tests_errexit -eq 1 ]] || set -o errexit
+        return 0
+    fi
+}
+
+
+_assert_reset
+: ${tests_suite_status:=0}  # remember if any of the tests failed so far
+_assert_cleanup() {
+    local status=$?
+    # modify exit code if it's not already non-zero
+    [[ $status -eq 0 && -z $CONTINUE ]] && exit $tests_suite_status
+}
+trap _assert_cleanup EXIT