diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..3aefff8
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+test/assert.sh
+test/stub.sh
diff --git a/Makefile b/Makefile
index 7077688..e4608f5 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,24 @@
+test: build prepare
+	./test.sh
+
 build:
 	./build.sh
 
-test: build
-	./test.sh
+prepare: prepare-assert.sh prepare-stub.sh
+
+prepare-assert.sh:
+	test -f "test/assert.sh" || ( \
+		echo "fetching assert.sh..." && \
+		curl -s -L -o test/assert.sh \
+			https://raw.github.com/lehmannro/assert.sh/master/assert.sh \
+	)
+
+prepare-stub.sh:
+	test -f "test/stub.sh" || ( \
+		echo "fetching stub.sh..." && \
+		curl -s -L -o test/stub.sh \
+			https://raw.github.com/jimeh/stub.sh/master/stub.sh \
+	)
 
 .SILENT:
-.PHONY: build test
+.PHONY: build test prepare preare-assert.sh prepare-stub.sh
diff --git a/test/assert.sh b/test/assert.sh
deleted file mode 100644
index f3d03d8..0000000
--- a/test/assert.sh
+++ /dev/null
@@ -1,139 +0,0 @@
-#!/bin/bash
-# assert.sh 1.0 - bash unit testing framework
-# Copyright (C) 2009, 2010, 2011, 2012 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:-}
-
-args="$(getopt -n "$0" -l verbose,help,stop,discover,invariant vhxdi $*)" \
-|| exit -1
-for arg in $args; do
-    case "$arg" in
-        -h)
-            echo "$0 [-vxid] [--verbose] [--stop] [--invariant] [--discover]"
-            echo "`sed 's/./ /g' <<< "$0"` [-h] [--help]"
-            exit 0;;
-        --help)
-            cat <<EOF
-Usage: $0 [options]
-Language-agnostic unit tests for subprocesses.
-
-Options:
-  -v, --verbose    generate output for every individual test case
-  -x, --stop       stop running tests after the first failure
-  -i, --invariant  do not measure timings to remain invariant between runs
-  -d, --discover   collect test suites only, do not run any tests
-  -h               show brief usage information and exit
-  --help           show this help message and exit
-EOF
-            exit 0;;
-        -v|--verbose)
-            DEBUG=1;;
-        -x|--stop)
-            STOP=1;;
-        -i|--invariant)
-            INVARIANT=1;;
-        -d|--discover)
-            DISCOVERONLY=1;;
-    esac
-done
-
-printf -v _indent "\n\t" # local format helper
-
-_assert_reset() {
-    tests_ran=0
-    tests_failed=0
-    tests_errors=()
-    tests_starttime="$(date +%s.%N)" # seconds_since_epoch.nanoseconds
-}
-
-assert_end() {
-    # assert_end [suite ..]
-    tests_endtime="$(date +%s.%N)"
-    tests="$tests_ran ${*:+$* }tests"
-    [[ -n "$DISCOVERONLY" ]] && echo "collected $tests." && _assert_reset && return
-    [[ -n "$DEBUG" ]] && echo
-    [[ -z "$INVARIANT" ]] && report_time=" in $(bc \
-        <<< "${tests_endtime%.N} - ${tests_starttime%.N}" \
-        | sed -e 's/\.\([0-9]\{0,3\}\)[0-9]*/.\1/' -e 's/^\./0./')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
-    _assert_reset
-    return $tests_failed_previous
-}
-
-assert() {
-    # assert <command> <expected stdout> [stdin]
-    (( tests_ran++ ))
-    [[ -n "$DISCOVERONLY" ]] && return
-    # printf required for formatting
-    printf -v expected "x${2:-}" # x required to overwrite older results
-    result="$(eval 2>/dev/null $1 <<< ${3:-})"
-    # Note: $expected is already decorated
-    if [[ "x$result" == "$expected" ]]; then
-        [[ -n "$DEBUG" ]] && echo -n .
-        return
-    fi
-    [[ -n "$DEBUG" ]] && echo -n X
-    result="$(sed -e :a -e '$!N;s/\n/\\n/;ta' <<< "$result")"
-    [[ -z "$result" ]] && result="nothing" || result="\"$result\""
-    [[ -z "$2" ]] && expected="nothing" || expected="\"$2\""
-    failure="expected $expected${_indent}got $result"
-    report="test #$tests_ran \"$1${3:+ <<< $3}\" failed:${_indent}$failure"
-    tests_errors[$tests_failed]="$report"
-    (( tests_failed++ ))
-    if [[ -n "$STOP" ]]; then
-        [[ -n "$DEBUG" ]] && echo
-        echo "$report"
-        exit 1
-    fi
-}
-
-assert_raises() {
-    # assert_raises <command> <expected code> [stdin]
-    (( tests_ran++ ))
-    [[ -n "$DISCOVERONLY" ]] && return
-    (eval $1 <<< ${3:-}) > /dev/null 2>&1
-    status=$?
-    expected=${2:-0}
-    if [[ "$status" -eq "$expected" ]]; then
-        [[ -n "$DEBUG" ]] && echo -n .
-        return
-    fi
-    [[ -n "$DEBUG" ]] && echo -n X
-    failure="program terminated with code $status instead of $expected"
-    report="test #$tests_ran \"$1${3:+ <<< $3}\" failed:${_indent}$failure"
-    tests_errors[$tests_failed]="$report"
-    (( tests_failed++ ))
-    if [[ -n "$STOP" ]]; then
-        [[ -n "$DEBUG" ]] && echo
-        echo "$report"
-        exit 1
-    fi
-}
-
-_assert_reset
diff --git a/test/stub.sh b/test/stub.sh
deleted file mode 100644
index e262fdb..0000000
--- a/test/stub.sh
+++ /dev/null
@@ -1,35 +0,0 @@
-# Stub commands for testing purposes.
-#
-# Arguments:
-#   - $1: Name of command to stub.
-#   - $2: Output will go to STDERR when $2 is "STDERR".
-#
-stub() {
-  local cmd="$1"
-  if [ "$2" == "STDERR" ]; then local redirect=" 1>&2"; fi
-
-  if [[ "$(type "$cmd" | head -1)" == *"is a function" ]]; then
-    local source="$(type "$cmd" | tail -n +2)"
-    source="${source/$cmd/non_stubbed_${cmd}}"
-    eval "$source"
-  fi
-  eval "$(echo -e "${1}() {\n  echo \"$1 stub: \$@\"$redirect\n}")"
-}
-
-# Restore the original command/function that was stubbed with stub().
-#
-# Arguments:
-#   - $1: Name of command to restore.
-#
-restore() {
-  local cmd="$1"
-  unset -f "$cmd"
-  if type "non_stubbed_${cmd}" &>/dev/null; then
-    if [[ "$(type "non_stubbed_${cmd}" | head -1)" == *"is a function" ]]; then
-      local source="$(type "non_stubbed_$cmd" | tail -n +2)"
-      source="${source/non_stubbed_${cmd}/$cmd}"
-      eval "$source"
-      unset -f "non_stubbed_${cmd}"
-    fi
-  fi
-}