add unit tests

bin/test

+#!/usr/bin/env bash
+
+#
+# Create a Heroku app with the following buildpack:
+# https://github.com/ddollar/buildpack-test
+#
+# Push this buildpack to the Heroku app to run the tests
+#
+
+testDetectWithPackageJson() {
+  detect package-json-version
+  assertCaptured "Node.js"
+  assertCapturedSuccess
+}
+
+testDetectWithoutPackageJson() {
+  detect no-package-json
+  assertCapturedError 1 ""
+}
+
+testPackageJsonWithVersion() {
+  compile package-json-version
+  assertCaptured "Using Node.js version: 0.6.11"
+  assertCaptured "Using npm version: 1.1.9"
+  assertCapturedSuccess
+}
+
+testPackageJsonWithNoVersion() {
+  compile package-json-noversion
+  assertCaptured "Using Node.js version: 0.4.7"
+  assertCaptured "Using npm version: 1.0.106"
+  assertCapturedSuccess
+}
+
+## utils ########################################
+
+pushd $(dirname 0) >/dev/null
+BASE=$(pwd)
+popd >/dev/null
+
+source ${BASE}/vendor/test-utils/test-utils
+
+detect() {
+  capture ${BASE}/bin/detect ${BASE}/test/$1
+}
+
+compile() {
+  capture ${BASE}/bin/compile ${BASE}/test/$1
+}
+
+source ${BASE}/vendor/shunit2/shunit2

test/package-json-noversion/package.json

+{
+  "name": "myapp",
+  "version": "0.0.1"
+}

test/package-json-version/package.json

+{
+  "name": "myapp",
+  "version": "0.0.1",
+
+  "engines": {
+    "node": "0.6.11",
+    "npm": "1.1.9"
+  }
+}

vendor/test-utils/test-utils

+#!/bin/sh
+
+# taken from
+# https://github.com/ryanbrainard/heroku-buildpack-testrunner/blob/master/lib/test_utils.sh
+
+oneTimeSetUp()
+{
+   TEST_SUITE_CACHE="$(mktemp -d ${SHUNIT_TMPDIR}/test_suite_cache.XXXX)"
+}
+
+oneTimeTearDown()
+{
+  rm -rf ${TEST_SUITE_CACHE}
+}
+
+setUp()
+{
+  OUTPUT_DIR="$(mktemp -d ${SHUNIT_TMPDIR}/output.XXXX)"
+  STD_OUT="${OUTPUT_DIR}/stdout"
+  STD_ERR="${OUTPUT_DIR}/stderr"
+  BUILD_DIR="${OUTPUT_DIR}/build"
+  CACHE_DIR="${OUTPUT_DIR}/cache"
+  mkdir -p ${OUTPUT_DIR}
+  mkdir -p ${BUILD_DIR}
+  mkdir -p ${CACHE_DIR}
+}
+
+tearDown()
+{
+  rm -rf ${OUTPUT_DIR}
+}
+
+capture()
+{
+  resetCapture
+
+  LAST_COMMAND="$@"
+
+  $@ >${STD_OUT} 2>${STD_ERR}
+  RETURN=$?
+  rtrn=${RETURN} # deprecated
+}
+
+resetCapture()
+{
+  if [ -f ${STD_OUT} ]; then
+    rm ${STD_OUT}
+  fi
+
+  if [ -f ${STD_ERR} ]; then
+    rm ${STD_ERR}
+  fi
+
+  unset LAST_COMMAND
+  unset RETURN
+  unset rtrn # deprecated
+}
+
+detect()
+{
+  capture ${BUILDPACK_HOME}/bin/detect ${BUILD_DIR}
+}
+
+compile()
+{
+  capture ${BUILDPACK_HOME}/bin/compile ${BUILD_DIR} ${CACHE_DIR}
+}
+
+release()
+{
+  capture ${BUILDPACK_HOME}/bin/release ${BUILD_DIR}
+}
+
+assertCapturedEquals()
+{
+  assertEquals "$@" "$(cat ${STD_OUT})"
+}
+
+assertCapturedNotEquals()
+{
+  assertNotEquals "$@" "$(cat ${STD_OUT})"
+}
+
+assertCaptured()
+{
+  assertFileContains "$@" "${STD_OUT}"
+}
+
+assertNotCaptured()
+{
+  assertFileNotContains "$@" "${STD_OUT}"
+}
+
+assertCapturedSuccess()
+{
+  assertEquals "Expected captured exit code to be 0; was <${RETURN}>" "0" "${RETURN}"
+  assertEquals "Expected STD_ERR to be empty; was <$(cat ${STD_ERR})>" "" "$(cat ${STD_ERR})"
+}
+
+# assertCapturedError [[expectedErrorCode] expectedErrorMsg]
+assertCapturedError()
+{
+  if [ $# -gt 1 ]; then
+    expectedErrorCode=${1}
+    shift
+  fi
+
+  expectedErrorMsg=${1:-""}
+
+  if [ -z ${expectedErrorCode} ]; then
+    assertTrue "Expected captured exit code to be greater than 0; was <${RETURN}>" "[ ${RETURN} -gt 0 ]"
+  else
+    assertTrue "Expected captured exit code to be <${expectedErrorCode}>; was <${RETURN}>" "[ ${RETURN} -eq ${expectedErrorCode} ]"
+  fi
+
+  assertFileContains "Expected STD_OUT to contain error <${expectedErrorMsg}>" "${expectedErrorMsg}" "${STD_OUT}"
+  assertEquals       "STD_ERR should always be empty" "" "$(cat ${STD_ERR})"
+}
+
+assertAppDetected()
+{
+  expectedAppType=${1?"Must provide app type"}
+
+  assertCapturedSuccess
+  assertEquals "${expectedAppType}" "$(cat ${STD_OUT})"
+}
+
+assertNoAppDetected()
+{
+  assertEquals "1" "${RETURN}"
+  assertEquals "no" "$(cat ${STD_OUT})"
+  assertEquals "" "$(cat ${STD_ERR})"
+}
+
+_assertContains()
+{
+  if [ 5 -eq $# ]; then
+    msg=$1
+    shift
+  elif [ ! 4 -eq $# ]; then
+    fail "Expected 4 or 5 parameters; Receieved $# parameters"
+  fi
+
+  needle=$1
+  haystack=$2
+  expectation=$3
+  haystack_type=$4
+
+  case "${haystack_type}" in
+    "file") grep -q -F -e "${needle}" ${haystack} ;;
+    "text") echo "${haystack}" | grep -q -F -e "${needle}" ;;
+  esac
+
+  if [ "${expectation}" != "$?" ]; then
+    case "${expectation}" in
+      0) default_msg="Expected <${haystack}> to contain <${needle}>" ;;
+      1) default_msg="Did not expect <${haystack}> to contain <${needle}>" ;;
+    esac
+
+    fail "${msg:-${default_msg}}"
+  fi
+}
+
+assertContains()
+{
+  _assertContains "$@" 0 "text"
+}
+
+assertNotContains()
+{
+  _assertContains "$@" 1 "text"
+}
+
+assertFileContains()
+{
+  _assertContains "$@" 0 "file"
+}
+
+assertFileNotContains()
+{
+  _assertContains "$@" 1 "file"
+}
+
+command_exists () {
+    type "$1" > /dev/null 2>&1 ;
+}
+
+assertFileMD5()
+{
+  expectedHash=$1
+  filename=$2
+
+  if command_exists "md5sum"; then
+    md5_cmd="md5sum ${filename}"
+    expected_md5_cmd_output="${expectedHash}  ${filename}"
+  elif command_exists "md5"; then
+    md5_cmd="md5 ${filename}"
+    expected_md5_cmd_output="MD5 (${filename}) = ${expectedHash}"
+  else
+    fail "no suitable MD5 hashing command found on this system"
+  fi
+
+  assertEquals "${expected_md5_cmd_output}" "`${md5_cmd}`"
+}