v98

The Node buildpack now exports a leading zero in its numbers. This lets us detect that it (or another buildpack) set the value, and overwrite it accordingly.

Fixes the issue where adding the node buildpack to a Python app would cause only one gunicorn worker to be spawned for a 1X dyno, and not two.

We also need to again produce leading zeroes in the value, so that e.g. the PHP buildpack can do the same on boot.

.travis.yml

@@ -1,2 +1,6 @@
-sudo: false
-script: exit 0
+language: bash
+sudo: required
+services:
+  - docker
+install: docker pull heroku/cedar:14
+script: make test

CHANGELOG.md

@@ -1,12 +1,23 @@
 # Python Buildpack Changelog
 
+## 98
+
+Official NLTK support and other improvements.
+
+- Support for `nltk.txt` file for declaring corpora to be downloaded.
+- Leading zeros for auto-set WEB_CONCURRENCY.
+
+## 97
+
+Improved egg-link functionality.
+
 ## 96
 
 Bugfix.
 
 ## 95
 
-Improved output support. 
+Improved output support.
 
 ## v94
 
@@ -18,7 +29,7 @@ Improved support for PyPy.
 
 ## v92
 
-Improved cache functionality and fix egg-links regression. 
+Improved cache functionality and fix egg-links regression.
 
 ## v91
 
@@ -30,11 +41,11 @@ Bugfix.
 
 ## v89
 
-Improved cache functionality and fix egg-links regression. 
+Improved cache functionality and fix egg-links regression.
 
 ## v88
 
-Fixed bug with editable pip installations. 
+Fixed bug with editable pip installations.
 
 ## v87
 
@@ -49,7 +60,7 @@ Refactor and multi-buildpack compatibility.
 
 ## v85
 
-Packaging fix. 
+Packaging fix.
 
 ## v84
 

Makefile

@@ -1,8 +1,12 @@
 # These targets are not files
 .PHONY: tests
 
-tests:
-	./bin/test
+test: test-cedar-14
+
+test-cedar-14:
+	@echo "Running tests in docker (cedar-14)..."
+	@docker run -v $(shell pwd):/buildpack:ro --rm -it -e "STACK=cedar-14" heroku/cedar:14 bash -c 'cp -r /buildpack /buildpack_test; cd /buildpack_test/; test/run;'
+	@echo ""
 
 tools:
 	git clone https://github.com/kennethreitz/pip-pop.git

README.md

@@ -2,6 +2,8 @@
 
 # Heroku Buildpack: Python
 
+[![Build Status](https://travis-ci.org/heroku/heroku-buildpack-python.svg?branch=master)](https://travis-ci.org/heroku/heroku-buildpack-python)
+
 This is the official [Heroku buildpack](https://devcenter.heroku.com/articles/buildpacks) for Python apps, powered by [pip](https://pip.pypa.io/) and other excellent software.
 
 Recommended web frameworks include **Django** and **Flask**. The recommended webserver is **Gunicorn**. There are no restrictions around what software can be used (as long as it's pip-installable). Web processes must bind to `$PORT`, and only the HTTP protocol is permitted for incoming connections.

bin/compile

@@ -193,6 +193,9 @@ source $BIN_DIR/steps/gdal
 # Install dependencies with Pip (where the magic happens).
 source $BIN_DIR/steps/pip-install
 
+# Support for NLTK corpora.
+sub-env $BIN_DIR/steps/nltk
+
 # Support for pip install -e.
 rm -fr $BUILD_DIR/.heroku/src
 deep-cp /app/.heroku/src $BUILD_DIR/.heroku/src

bin/steps/nltk

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+# This script serves as the NLTK build step of the
+# [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
+# compiler.
+#
+# A [buildpack](https://devcenter.heroku.com/articles/buildpacks) is an
+# adapter between a Python application and Heroku's runtime.
+#
+# This script is invoked by [`bin/compile`](/).
+
+# Syntax sugar.
+source $BIN_DIR/utils
+
+bpwatch start nltk_download
+
+export NLTK_DATA_DIR="$BUILD_DIR/nltk_data"
+export NLTK_DATA="$BUILD_DIR/nltk_data"
+
+# Check that nltk was installed by pip, otherwise obviously not needed
+python -m nltk.downloader -h >/dev/null 2>&1
+if [ $? -eq 0 ]; then
+    puts-step "Downloading NLTK corpora..."
+    nltk_packages_definition="$BUILD_DIR/nltk.txt"
+    if [ -f "$nltk_packages_definition" ]; then
+        nltk_packages=$(tr "\n" " " < "$nltk_packages_definition")
+        puts-step "Downloading NLTK packages: $nltk_packages"
+        python -m nltk.downloader -d $BUILD_DIR/.heroku/python/nltk_data $nltk_packages  | indent
+        set-env NLTK_DATA "/app/.heroku/python/nltk_data"
+    else
+        puts-warn "nltk.txt not found, not downloading any corpora"
+    fi
+else
+    puts-warn "nltk not apparently installed, not downloading packages"
+fi
+
+
+bpwatch stop nltk_download

test/fixtures/psycopg2/requirements.txt

@@ -0,0 +1 @@
+psycopg2

test/fixtures/python2/requirements.txt

@@ -0,0 +1 @@
+requests

test/fixtures/python2/runtime.txt

@@ -0,0 +1 @@
+python-2.7.13

test/fixtures/python3/requirements.txt

@@ -0,0 +1 @@
+requests

test/fixtures/python3/runtime.txt

@@ -0,0 +1 @@
+python-3.6.0

test/fixtures/requirements-standard/requirements.txt

@@ -0,0 +1 @@
+requests

test/fixtures/setup-py/README.rst

@@ -0,0 +1,114 @@
+Maya: Datetime for Humans™
+==========================
+
+.. image:: https://img.shields.io/pypi/v/maya.svg
+    :target: https://pypi.python.org/pypi/maya
+
+.. image:: https://travis-ci.org/kennethreitz/maya.svg?branch=master
+    :target: https://travis-ci.org/kennethreitz/maya
+
+.. image:: https://img.shields.io/badge/SayThanks.io-☼-1EAEDB.svg
+    :target: https://saythanks.io/to/kennethreitz
+
+
+Datetimes are very frustrating to work with in Python, especially when dealing
+with different locales on different systems. This library exists to make the
+simple things **much** easier, while admitting that time is an illusion
+(timezones doubly so).
+
+Datetimes should be interacted with via an API written for humans.
+
+Maya is mostly built around the headaches and use-cases around parsing datetime data from websites.
+
+
+☤ Basic Usage of Maya
+---------------------
+
+Behold, datetimes for humans!
+
+.. code-block:: pycon
+
+    >>> now = maya.now()
+    <MayaDT epoch=1481850660.9>
+
+    >>> tomorrow = maya.when('tomorrow')
+    <MayaDT epoch=1481919067.23>
+
+    >>> tomorrow.slang_date()
+    'tomorrow'
+
+    >>> tomorrow.slang_time()
+    '23 hours from now'
+
+    >>> tomorrow.iso8601()
+    '2016-12-16T15:11:30.263350Z'
+
+    >>> tomorrow.rfc2822()
+    'Fri, 16 Dec 2016 20:11:30 -0000'
+
+    >>> tomorrow.datetime()
+    datetime.datetime(2016, 12, 16, 15, 11, 30, 263350, tzinfo=<UTC>)
+
+    # Automatically parse datetime strings and generate naive datetimes.
+    >>> scraped = '2016-12-16 18:23:45.423992+00:00'
+    >>> maya.parse(scraped).datetime(to_timezone='US/Eastern', naive=True)
+    datetime.datetime(2016, 12, 16, 13, 23, 45, 423992)
+
+    >>> rand_day = maya.when('2011-02-07', timezone='US/Eastern')
+    <MayaDT epoch=1297036800.0>
+
+    # Note how this is the 6th, not the 7th.
+    >>> rand_day.day
+    6
+
+    # Always.
+    >>> rand_day.timezone
+    UTC
+
+☤ Why is this useful?
+---------------------
+
+- All timezone algebra will behave identically on all machines, regardless of system locale.
+- Complete symmetric import and export of both ISO 8601 and RFC 2822 datetime stamps.
+- Fantastic parsing of both dates written for/by humans and machines (``maya.when()`` vs ``maya.parse()``).
+- Support for human slang, both import and export (e.g. `an hour ago`).
+- Datetimes can very easily be generated, with or without tzinfo attached.
+- This library is based around epoch time, but dates before Jan 1 1970 are indeed supported, via negative integers.
+- Maya never panics, and always carries a towel.
+
+
+☤ What about Delorean, Arrow, & Pendulum?
+-----------------------------------------
+
+Arrow, for example, is a fantastic library, but isn't what I wanted in a datetime library. In many ways, it's better than Maya for certain things. In some ways, in my opinion, it's not.
+
+I simply desire a sane API for datetimes that made sense to me for all the things I'd ever want to do—especially when dealing with timezone algebra. Arrow doesn't do all of the things I need (but it does a lot more!). Maya does do exactly what I need.
+
+I think these projects complement each-other, personally. Maya is great for parsing websites. For example- Arrow supports floors and ceilings and spans of dates, which Maya does not at all.
+
+
+☤ Installing Maya
+-----------------
+
+Installation is easy, with pip::
+
+    $ pip install maya
+
+✨🍰✨
+
+☤ Like it?
+----------
+
+`Say Thanks <https://saythanks.io/to/kennethreitz>`_!
+
+
+How to Contribute
+-----------------
+
+#. Check for open issues or open a fresh issue to start a discussion around a feature idea or a bug.
+#. Fork `the repository`_ on GitHub to start making your changes to the **master** branch (or branch off of it).
+#. Write a test which shows that the bug was fixed or that the feature works as expected.
+#. Send a pull request and bug the maintainer until it gets merged and published. :) Make sure to add yourself to AUTHORS_.
+
+.. _`the repository`: http://github.com/kennethreitz/maya
+.. _AUTHORS: https://github.com/kennethreitz/maya/blob/master/AUTHORS.rst

test/fixtures/setup-py/maya.py

@@ -0,0 +1,273 @@
+
+# ___  __  ___  _  _  ___
+# || \/ | ||=|| \\// ||=||
+# ||    | || ||  //  || ||
+
+# Ignore warnings for yaml usage.
+import warnings
+import ruamel.yaml
+warnings.simplefilter('ignore', ruamel.yaml.error.UnsafeLoaderWarning)
+
+
+import email.utils
+import time
+from datetime import datetime as Datetime
+
+import pytz
+import humanize
+import dateparser
+import iso8601
+import dateutil.parser
+from tzlocal import get_localzone
+
+_EPOCH_START = (1970, 1, 1)
+
+
+def validate_class_type_arguments(operator):
+    """
+    Decorator to validate all the arguments to function
+    are of the type of calling class
+    """
+
+    def inner(function):
+        def wrapper(self, *args, **kwargs):
+            for arg in args + tuple(kwargs.values()):
+                if not isinstance(arg, self.__class__):
+                    raise TypeError('unorderable types: {}() {} {}()'.format(
+                        type(self).__name__, operator, type(arg).__name__))
+            return function(self, *args, **kwargs)
+
+        return wrapper
+
+    return inner
+
+
+
+class MayaDT(object):
+    """The Maya Datetime object."""
+
+    def __init__(self, epoch):
+        super(MayaDT, self).__init__()
+        self._epoch = epoch
+
+    def __repr__(self):
+        return '<MayaDT epoch={}>'.format(self._epoch)
+
+    def __str__(self):
+        return self.rfc2822()
+
+    def __format__(self, *args, **kwargs):
+        """Return's the datetime's format"""
+        return format(self.datetime(), *args, **kwargs)
+
+
+    @validate_class_type_arguments('==')
+    def __eq__(self, maya_dt):
+        return self._epoch == maya_dt._epoch
+
+    @validate_class_type_arguments('!=')
+    def __ne__(self, maya_dt):
+        return self._epoch != maya_dt._epoch
+
+    @validate_class_type_arguments('<')
+    def __lt__(self, maya_dt):
+        return self._epoch < maya_dt._epoch
+
+    @validate_class_type_arguments('<=')
+    def __le__(self, maya_dt):
+        return self._epoch <= maya_dt._epoch
+
+    @validate_class_type_arguments('>')
+    def __gt__(self, maya_dt):
+        return self._epoch > maya_dt._epoch
+
+    @validate_class_type_arguments('>=')
+    def __ge__(self, maya_dt):
+        return self._epoch >= maya_dt._epoch
+
+
+    # Timezone Crap
+    # -------------
+
+    @property
+    def timezone(self):
+        """Returns the UTC tzinfo name. It's always UTC. Always."""
+        return 'UTC'
+
+    @property
+    def _tz(self):
+        """Returns the UTC tzinfo object."""
+        return pytz.timezone(self.timezone)
+
+    @property
+    def local_timezone(self):
+        """Returns the name of the local timezone, for informational purposes."""
+        return self._local_tz.zone
+
+    @property
+    def _local_tz(self):
+        """Returns the local timezone."""
+        return get_localzone()
+
+    @staticmethod
+    def __dt_to_epoch(dt):
+        """Converts a datetime into an epoch."""
+
+        # Assume UTC if no datetime is provided.
+        if dt.tzinfo is None:
+            dt = dt.replace(tzinfo=pytz.utc)
+
+        epoch_start = Datetime(*_EPOCH_START, tzinfo=pytz.timezone('UTC'))
+        return (dt - epoch_start).total_seconds()
+
+    # Importers
+    # ---------
+
+    @classmethod
+    def from_datetime(klass, dt):
+        """Returns MayaDT instance from datetime."""
+        return klass(klass.__dt_to_epoch(dt))
+
+    @classmethod
+    def from_iso8601(klass, string):
+        """Returns MayaDT instance from iso8601 string."""
+        dt = iso8601.parse_date(string)
+        return klass.from_datetime(dt)
+
+    @staticmethod
+    def from_rfc2822(string):
+        """Returns MayaDT instance from rfc2822 string."""
+        return parse(string)
+
+    # Exporters
+    # ---------
+
+    def datetime(self, to_timezone=None, naive=False):
+        """Returns a timezone-aware datetime...
+        Defaulting to UTC (as it should).
+
+        Keyword Arguments:
+            to_timezone {string} -- timezone to convert to (default: None/UTC)
+            naive {boolean} -- if True, the tzinfo is simply dropped (default: False)
+        """
+        if to_timezone:
+            dt = self.datetime().astimezone(pytz.timezone(to_timezone))
+        else:
+            dt = Datetime.utcfromtimestamp(self._epoch)
+            dt.replace(tzinfo=self._tz)
+
+        # Strip the timezone info if requested to do so.
+        if naive:
+            return dt.replace(tzinfo=None)
+        else:
+            if dt.tzinfo is None:
+                dt = dt.replace(tzinfo=self._tz)
+
+        return dt
+
+    def iso8601(self):
+        """Returns an ISO 8601 representation of the MayaDT."""
+        # Get a timezone-naive datetime.
+        dt = self.datetime(naive=True)
+        return '{}Z'.format(dt.isoformat())
+
+    def rfc2822(self):
+        """Returns an RFC 2822 representation of the MayaDT."""
+        return email.utils.formatdate(self.epoch, usegmt=True)
+
+    # Properties
+    # ----------
+
+    @property
+    def year(self):
+        return self.datetime().year
+
+    @property
+    def month(self):
+        return self.datetime().month
+
+    @property
+    def day(self):
+        return self.datetime().day
+
+    @property
+    def week(self):
+        return self.datetime().isocalendar()[1]
+
+    @property
+    def weekday(self):
+        """Return the day of the week as an integer. Monday is 1 and Sunday is 7"""
+        return self.datetime().isoweekday()
+
+    @property
+    def hour(self):
+        return self.datetime().hour
+
+    @property
+    def minute(self):
+        return self.datetime().minute
+
+    @property
+    def second(self):
+        return self.datetime().second
+
+    @property
+    def microsecond(self):
+        return self.datetime().microsecond
+
+    @property
+    def epoch(self):
+        return self._epoch
+
+    # Human Slang Extras
+    # ------------------
+
+    def slang_date(self):
+        """"Returns human slang representation of date."""
+        dt = self.datetime(naive=True, to_timezone=self.local_timezone)
+        return humanize.naturaldate(dt)
+
+    def slang_time(self):
+        """"Returns human slang representation of time."""
+        dt = self.datetime(naive=True, to_timezone=self.local_timezone)
+        return humanize.naturaltime(dt)
+
+
+
+
+def now():
+    """Returns a MayaDT instance for this exact moment."""
+    epoch = time.time()
+    return MayaDT(epoch=epoch)
+
+def when(string, timezone='UTC'):
+    """"Returns a MayaDT instance for the human moment specified.
+
+    Powered by dateparser. Useful for scraping websites.
+
+    Examples:
+        'next week', 'now', 'tomorrow', '300 years ago', 'August 14, 2015'
+
+    Keyword Arguments:
+        string -- string to be parsed
+        timezone -- timezone referenced from (default: 'UTC')
+
+    """
+    dt = dateparser.parse(string, settings={'TIMEZONE': timezone, 'RETURN_AS_TIMEZONE_AWARE': True, 'TO_TIMEZONE': 'UTC'})
+
+    if dt is None:
+        raise ValueError('invalid datetime input specified.')
+
+    return MayaDT.from_datetime(dt)
+
+def parse(string, day_first=False):
+    """"Returns a MayaDT instance for the machine-produced moment specified.
+
+    Powered by dateutil. Accepts most known formats. Useful for working with data.
+
+    Keyword Arguments:
+        string -- string to be parsed
+        day_first -- if true, the first value (e.g. 01/05/2016) is parsed as day (default: False)
+    """
+    dt = dateutil.parser.parse(string, dayfirst=day_first)
+    return MayaDT.from_datetime(dt)

test/fixtures/setup-py/setup.py

@@ -0,0 +1,51 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+import os
+import sys
+import codecs
+
+from setuptools import setup
+
+try:
+    # Python 3
+    from os import dirname
+except ImportError:
+    # Python 2
+    from os.path import dirname
+
+here = os.path.abspath(dirname(__file__))
+
+with codecs.open(os.path.join(here, 'README.rst'), encoding='utf-8') as f:
+    long_description = '\n' + f.read()
+
+
+if sys.argv[-1] == "publish":
+    os.system("python setup.py sdist bdist_wheel upload")
+    sys.exit()
+
+required = [
+    'humanize',
+    'pytz',
+    'dateparser',
+    'iso8601',
+    'python-dateutil',
+    'ruamel.yaml',
+    'tzlocal'
+]
+
+setup(
+    name='maya',
+    version='0.1.6',
+    description='Datetimes for Humans.',
+    long_description=long_description,
+    author='Kenneth Reitz',
+    author_email='me@kennethreitz.com',
+    url='https://github.com/kennethreitz/maya',
+    py_modules=['maya'],
+    install_requires=required,
+    license='MIT',
+    classifiers=(
+
+    ),
+)

test/run

@@ -0,0 +1,99 @@
+#!/usr/bin/env bash
+
+testNoRequirements() {
+  compile "no-requirements"
+  assertCapturedError
+}
+
+
+testSetupPy() {
+  compile "setup-py"
+  assertCaptured "maya"
+  assertCapturedSuccess
+}
+
+
+testStandardRequirements() {
+  compile "requirements-standard"
+  assertCaptured "requests"
+  assertCapturedSuccess
+}
+
+testPsycopg2() {
+  compile "psycopg2"
+  assertCaptured "psycopg2"
+  assertCapturedSuccess
+}
+
+testPython2() {
+  compile "python2"
+  assertCaptured "python-2.7.13"
+  assertCapturedSuccess
+}
+
+testPython3() {
+  compile "python3"
+  assertCaptured "python-3.6.0"
+  assertCapturedSuccess
+}
+
+
+
+
+pushd $(dirname 0) >/dev/null
+popd >/dev/null
+
+source $(pwd)/test/utils
+
+mktmpdir() {
+  dir=$(mktemp -t testXXXXX)
+  rm -rf $dir
+  mkdir $dir
+  echo $dir
+}
+
+detect() {
+  capture $(pwd)/bin/detect $(pwd)/test/fixtures/$1
+}
+
+compile_dir=""
+
+default_process_types_cleanup() {
+  file="/tmp/default_process_types"
+  if [ -f "$file" ]; then
+    rm "$file"
+  fi
+}
+
+compile() {
+  default_process_types_cleanup
+  bp_dir=$(mktmpdir)
+  compile_dir=$(mktmpdir)
+  cp -a $(pwd)/* ${bp_dir}
+  cp -a ${bp_dir}/test/fixtures/$1/. ${compile_dir}
+  capture ${bp_dir}/bin/compile ${compile_dir} ${2:-$(mktmpdir)} $3
+}
+
+compileDir() {
+  default_process_types_cleanup
+
+  local bp_dir=$(mktmpdir)
+  local compile_dir=${1:-$(mktmpdir)}
+  local cache_dir=${2:-$(mktmpdir)}
+  local env_dir=$3
+
+  cp -a $(pwd)/* ${bp_dir}
+  capture ${bp_dir}/bin/compile ${compile_dir} ${cache_dir} ${env_dir}
+}
+
+release() {
+  bp_dir=$(mktmpdir)
+  cp -a $(pwd)/* ${bp_dir}
+  capture ${bp_dir}/bin/release ${bp_dir}/test/fixtures/$1
+}
+
+assertFile() {
+  assertEquals "$1" "$(cat ${compile_dir}/$2)"
+}
+
+source $(pwd)/test/shunit2

test/utils

@@ -0,0 +1,195 @@
+#!/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 [ $# -gt 1 ]; then
+    local expectedErrorCode=${1}
+    shift
+  fi
+
+  local 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 ${expectedErrorCode} ]"
+  fi
+
+  if [ "${expectedErrorMsg}" != "" ]; then
+    assertFileContains "Expected STD_ERR to contain error <${expectedErrorMsg}>" "${expectedErrorMsg}" "${STD_ERR}"
+  fi
+}
+
+_assertContains()
+{
+  if [ 5 -eq $# ]; then
+    local msg=$1
+    shift
+  elif [ ! 4 -eq $# ]; then
+    fail "Expected 4 or 5 parameters; Receieved $# parameters"
+  fi
+
+  local needle=$1
+  local haystack=$2
+  local expectation=$3
+  local 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
+}
+
+debug()
+{
+  cat $STD_OUT
+}
+
+assertContains()
+{
+  _assertContains "$@" 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}`"
+}

vendor/python.gunicorn.sh

@@ -1,32 +1,38 @@
+if [[ "${WEB_CONCURRENCY:-}" == 0* ]]; then
+  # another buildpack set a default value, with leading zero
+  unset WEB_CONCURRENCY
+fi
+
 case $(ulimit -u) in
 
 # Automatic configuration for Gunicorn's Workers setting.
+# Leading zero padding so a subsequent buildpack can figure out that we set a value, and not the user
 
 # Standard-1X (+Free, +Hobby) Dyno
 256)
   export DYNO_RAM=512
-  export WEB_CONCURRENCY=${WEB_CONCURRENCY:-2}
+  export WEB_CONCURRENCY=${WEB_CONCURRENCY:-02}
   ;;
 
 # Standard-2X Dyno
 512)
   export DYNO_RAM=1024
-  export WEB_CONCURRENCY=${WEB_CONCURRENCY:-4}
+  export WEB_CONCURRENCY=${WEB_CONCURRENCY:-04}
   ;;
 
 # Performance-M Dyno
 16384)
   export DYNO_RAM=2560
-  export WEB_CONCURRENCY=${WEB_CONCURRENCY:-8}
+  export WEB_CONCURRENCY=${WEB_CONCURRENCY:-08}
   ;;
 
 # Performance-L Dyno
 32768)
   export DYNO_RAM=6656
-  export WEB_CONCURRENCY=${WEB_CONCURRENCY:-11}
+  export WEB_CONCURRENCY=${WEB_CONCURRENCY:-011}
   ;;
 
 esac
 
 # Automatic configuration for Gunicorn's ForwardedAllowIPS setting.
-export FORWARDED_ALLOW_IPS='*'
+export FORWARDED_ALLOW_IPS='*'