swift/doc/source/development_saio.rst

=======================
SAIO - Swift All In One
=======================

.. note::
    This guide assumes an existing Linux server. A physical machine or VM will
    work. We recommend configuring it with at least 2GB of memory and 40GB of
    storage space. We recommend using a VM in order to isolate Swift and its
    dependencies from other projects you may be working on.

---------------------------------------------
Instructions for setting up a development VM
---------------------------------------------

This section documents setting up a virtual machine for doing Swift
development.  The virtual machine will emulate running a four node Swift
cluster. To begin:

* Get a linux system server image, this guide will cover:

  * Ubuntu 14.04, 16.04 LTS
  * Fedora/CentOS
  * OpenSuse

- Create guest virtual machine from the image.

----------------------------
What's in a <your-user-name>
----------------------------

Much of the configuration described in this guide requires escalated
administrator (``root``) privileges; however, we assume that administrator logs
in as an unprivileged user and can use ``sudo`` to run privileged commands.

Swift processes also run under a separate user and group, set by configuration
option, and referenced as ``<your-user-name>:<your-group-name>``.  The default user
is ``swift``, which may not exist on your system.  These instructions are
intended to allow a developer to use his/her username for
``<your-user-name>:<your-group-name>``.

-----------------------
Installing dependencies
-----------------------

* On ``apt`` based systems::

        sudo apt-get update
        sudo apt-get install curl gcc memcached rsync sqlite3 xfsprogs \
                             git-core libffi-dev python-setuptools \
                             liberasurecode-dev libssl-dev
        sudo apt-get install python-coverage python-dev python-nose \
                             python-xattr python-eventlet \
                             python-greenlet python-pastedeploy \
                             python-netifaces python-pip python-dnspython \
                             python-mock

* On ``yum`` based systems::

        sudo yum update
        sudo yum install curl gcc memcached rsync sqlite xfsprogs git-core \
                         libffi-devel xinetd liberasurecode-devel \
                         openssl-devel python-setuptools \
                         python-coverage python-devel python-nose \
                         pyxattr python-eventlet \
                         python-greenlet python-paste-deploy \
                         python-netifaces python-pip python-dns \
                         python-mock

* On ``OpenSuse``::

        sudo zypper install curl gcc memcached rsync sqlite3 xfsprogs git-core \
                            libffi-devel liberasurecode-devel python2-setuptools \
                            libopenssl-devel
        sudo zypper install python2-coverage python-devel python2-nose \
                            python-xattr python-eventlet python2-greenlet \
                            python2-netifaces python2-pip python2-dnspython \
                            python2-mock

.. note::
   This installs necessary system dependencies and *most* of the python
   dependencies. Later in the process setuptools/distribute or pip will install
   and/or upgrade packages.

Next, choose either :ref:`partition-section` or :ref:`loopback-section`.

.. _partition-section:

Using a partition for storage
=============================

If you are going to use a separate partition for Swift data, be sure to add
another device when creating the VM, and follow these instructions:

#. Set up a single partition::

      sudo fdisk /dev/sdb
      sudo mkfs.xfs /dev/sdb1

#. Edit ``/etc/fstab`` and add::

      /dev/sdb1 /mnt/sdb1 xfs noatime,nodiratime,nobarrier,logbufs=8 0 0

#. Create the mount point and the individualized links::

      sudo mkdir /mnt/sdb1
      sudo mount /mnt/sdb1
      sudo mkdir /mnt/sdb1/1 /mnt/sdb1/2 /mnt/sdb1/3 /mnt/sdb1/4
      sudo chown ${USER}:${USER} /mnt/sdb1/*
      sudo mkdir /srv
      for x in {1..4}; do sudo ln -s /mnt/sdb1/$x /srv/$x; done
      sudo mkdir -p /srv/1/node/sdb1 /srv/1/node/sdb5 \
                    /srv/2/node/sdb2 /srv/2/node/sdb6 \
                    /srv/3/node/sdb3 /srv/3/node/sdb7 \
                    /srv/4/node/sdb4 /srv/4/node/sdb8 \
                    /var/run/swift
      sudo chown -R ${USER}:${USER} /var/run/swift
      # **Make sure to include the trailing slash after /srv/$x/**
      for x in {1..4}; do sudo chown -R ${USER}:${USER} /srv/$x/; done

   .. note::
      For OpenSuse users, a user's primary group is ``users``, so you have 2 options:

      * Change ``${USER}:${USER}`` to ``${USER}:users`` in all references of this guide; or
      * Create a group for your username and add yourself to it::

         sudo groupadd ${USER} && sudo gpasswd -a ${USER} ${USER}

   .. note::
      We create the mount points and mount the storage disk under
      /mnt/sdb1. This disk will contain one directory per simulated swift node,
      each owned by the current swift user.

   We then create symlinks to these directories under /srv.
   If the disk sdb is unmounted, files will not be written under
   /srv/\*, because the symbolic link destination /mnt/sdb1/* will not
   exist. This prevents disk sync operations from writing to the root
   partition in the event a drive is unmounted.

#. Next, skip to :ref:`common-dev-section`.


.. _loopback-section:

Using a loopback device for storage
===================================

If you want to use a loopback device instead of another partition, follow
these instructions:

#. Create the file for the loopback device::

      sudo mkdir /srv
      sudo truncate -s 1GB /srv/swift-disk
      sudo mkfs.xfs /srv/swift-disk

   Modify size specified in the ``truncate`` command to make a larger or
   smaller partition as needed.

#. Edit `/etc/fstab` and add::

      /srv/swift-disk /mnt/sdb1 xfs loop,noatime,nodiratime,nobarrier,logbufs=8 0 0

#. Create the mount point and the individualized links::

      sudo mkdir /mnt/sdb1
      sudo mount /mnt/sdb1
      sudo mkdir /mnt/sdb1/1 /mnt/sdb1/2 /mnt/sdb1/3 /mnt/sdb1/4
      sudo chown ${USER}:${USER} /mnt/sdb1/*
      for x in {1..4}; do sudo ln -s /mnt/sdb1/$x /srv/$x; done
      sudo mkdir -p /srv/1/node/sdb1 /srv/1/node/sdb5 \
                    /srv/2/node/sdb2 /srv/2/node/sdb6 \
                    /srv/3/node/sdb3 /srv/3/node/sdb7 \
                    /srv/4/node/sdb4 /srv/4/node/sdb8 \
                    /var/run/swift
      sudo chown -R ${USER}:${USER} /var/run/swift
      # **Make sure to include the trailing slash after /srv/$x/**
      for x in {1..4}; do sudo chown -R ${USER}:${USER} /srv/$x/; done

   .. note::
      For OpenSuse users, a user's primary group is ``users``, so you have 2 options:

      * Change ``${USER}:${USER}`` to ``${USER}:users`` in all references of this guide; or
      * Create a group for your username and add yourself to it::

         sudo groupadd ${USER} && sudo gpasswd -a ${USER} ${USER}

   .. note::
      We create the mount points and mount the loopback file under
      /mnt/sdb1. This file will contain one directory per simulated swift node,
      each owned by the current swift user.

   We then create symlinks to these directories under /srv.
   If the loopback file is unmounted, files will not be written under
   /srv/\*, because the symbolic link destination /mnt/sdb1/* will not
   exist. This prevents disk sync operations from writing to the root
   partition in the event a drive is unmounted.

.. _common-dev-section:

Common Post-Device Setup
========================

Add the following lines to ``/etc/rc.local`` (before the ``exit 0``)::

        mkdir -p /var/cache/swift /var/cache/swift2 /var/cache/swift3 /var/cache/swift4
        chown <your-user-name>:<your-group-name> /var/cache/swift*
        mkdir -p /var/run/swift
        chown <your-user-name>:<your-group-name> /var/run/swift

Note that on some systems you might have to create ``/etc/rc.local``.

On Fedora 19 or later, you need to place these in ``/etc/rc.d/rc.local``.

On OpenSuse you need to place these in ``/etc/init.d/boot.local``.

Creating an XFS tmp dir
-----------------------

Tests require having an XFS directory available in ``/tmp`` or in the
``TMPDIR`` environment variable. To set up ``/tmp`` with an XFS filesystem,
do the following::

        cd ~
        truncate -s 1GB xfs_file  # create 1GB fil for XFS in your home directory
        mkfs.xfs xfs_file
        sudo mount -o loop,noatime,nodiratime xfs_file /tmp
        sudo chmod -R 1777 /tmp

To persist this, edit and add the following to ``/etc/fstab``::

        /home/<your-user-name>/xfs_file /tmp xfs rw,noatime,nodiratime,attr2,inode64,noquota 0 0

----------------
Getting the code
----------------

#. Check out the python-swiftclient repo::

      cd $HOME; git clone https://github.com/openstack/python-swiftclient.git

#. Build a development installation of python-swiftclient::

      cd $HOME/python-swiftclient; sudo python setup.py develop; cd -

   Ubuntu 12.04 users need to install python-swiftclient's dependencies before the installation of
   python-swiftclient. This is due to a bug in an older version of setup tools::

      cd $HOME/python-swiftclient; sudo pip install -r requirements.txt; sudo python setup.py develop; cd -

#. Check out the swift repo::

      git clone https://github.com/openstack/swift.git

#. Build a development installation of swift::

      cd $HOME/swift; sudo pip install --no-binary cryptography -r requirements.txt; sudo python setup.py develop; cd -

   .. note::
      Due to a difference in how ``libssl.so`` is named in OpenSuse vs. other Linux distros the
      wheel/binary won't work; thus we use ``--no-binary cryptography`` to build ``cryptography``
      locally.

   Fedora 19 or later users might have to perform the following if development
   installation of swift fails::

      sudo pip install -U xattr

#. Install swift's test dependencies::

      cd $HOME/swift; sudo pip install -r test-requirements.txt

----------------
Setting up rsync
----------------

#. Create ``/etc/rsyncd.conf``::

      sudo cp $HOME/swift/doc/saio/rsyncd.conf /etc/
      sudo sed -i "s/<your-user-name>/${USER}/" /etc/rsyncd.conf

   Here is the default ``rsyncd.conf`` file contents maintained in the repo
   that is copied and fixed up above:

   .. literalinclude:: /../saio/rsyncd.conf
      :language: ini

#. On Ubuntu, edit the following line in ``/etc/default/rsync``::

      RSYNC_ENABLE=true

   On Fedora, edit the following line in ``/etc/xinetd.d/rsync``::

      disable = no

   One might have to create the above files to perform the edits.

   On OpenSuse, nothing needs to happen here.

#. On platforms with SELinux in ``Enforcing`` mode, either set to ``Permissive``::

      sudo setenforce Permissive

   Or just allow rsync full access::

      sudo setsebool -P rsync_full_access 1

#. Start the rsync daemon

   * On Ubuntu 14.04, run::

      sudo service rsync restart

   * On Ubuntu 16.04, run::

      sudo systemctl enable rsync
      sudo systemctl start rsync

   * On Fedora, run::

      sudo systemctl restart xinetd.service
      sudo systemctl enable rsyncd.service
      sudo systemctl start rsyncd.service

   * On OpenSuse, run::

      sudo systemctl enable rsyncd.service
      sudo systemctl start rsyncd.service

   * On other xinetd based systems simply run::

      sudo service xinetd restart

#. Verify rsync is accepting connections for all servers::

      rsync rsync://pub@localhost/

   You should see the following output from the above command::

      account6012
      account6022
      account6032
      account6042
      container6011
      container6021
      container6031
      container6041
      object6010
      object6020
      object6030
      object6040

------------------
Starting memcached
------------------

On non-Ubuntu distros you need to ensure memcached is running::

        sudo service memcached start
        sudo chkconfig memcached on

or::

        sudo systemctl enable memcached.service
        sudo systemctl start memcached.service

The tempauth middleware stores tokens in memcached. If memcached is not
running, tokens cannot be validated, and accessing Swift becomes impossible.

---------------------------------------------------
Optional: Setting up rsyslog for individual logging
---------------------------------------------------

#. Install the swift rsyslogd configuration::

      sudo cp $HOME/swift/doc/saio/rsyslog.d/10-swift.conf /etc/rsyslog.d/

   Note: OpenSuse may have the systemd logger installed, so if you want this
   to work, you need to install rsyslog::

      sudo zypper install rsyslog
      sudo systemctl start rsyslog.service
      sudo systemctl enable rsyslog.service

   Be sure to review that conf file to determine if you want all the logs
   in one file vs. all the logs separated out, and if you want hourly logs
   for stats processing. For convenience, we provide its default contents
   below:

   .. literalinclude:: /../saio/rsyslog.d/10-swift.conf
      :language: ini

#. Edit ``/etc/rsyslog.conf`` and make the following change (usually in the
   "GLOBAL DIRECTIVES" section)::

      $PrivDropToGroup adm

#. If using hourly logs (see above) perform::

      sudo mkdir -p /var/log/swift/hourly

   Otherwise perform::

      sudo mkdir -p /var/log/swift

#. Setup the logging directory and start syslog:

   * On Ubuntu::

      sudo chown -R syslog.adm /var/log/swift
      sudo chmod -R g+w /var/log/swift
      sudo service rsyslog restart

   * On Fedora and OpenSuse::

      sudo chown -R root:adm /var/log/swift
      sudo chmod -R g+w /var/log/swift
      sudo systemctl restart rsyslog.service

---------------------
Configuring each node
---------------------

After performing the following steps, be sure to verify that Swift has access
to resulting configuration files (sample configuration files are provided with
all defaults in line-by-line comments).

#. Optionally remove an existing swift directory::

      sudo rm -rf /etc/swift

#. Populate the ``/etc/swift`` directory itself::

      cd $HOME/swift/doc; sudo cp -r saio/swift /etc/swift; cd -
      sudo chown -R ${USER}:${USER} /etc/swift

#. Update ``<your-user-name>`` references in the Swift config files::

      find /etc/swift/ -name \*.conf | xargs sudo sed -i "s/<your-user-name>/${USER}/"

The contents of the configuration files provided by executing the above
commands are as follows:

#. ``/etc/swift/swift.conf``

   .. literalinclude:: /../saio/swift/swift.conf
      :language: ini

#. ``/etc/swift/proxy-server.conf``

   .. literalinclude:: /../saio/swift/proxy-server.conf
      :language: ini

#. ``/etc/swift/object-expirer.conf``

   .. literalinclude:: /../saio/swift/object-expirer.conf
      :language: ini

#. ``/etc/swift/container-reconciler.conf``

   .. literalinclude:: /../saio/swift/container-reconciler.conf
      :language: ini

#. ``/etc/swift/container-sync-realms.conf``

   .. literalinclude:: /../saio/swift/container-sync-realms.conf
      :language: ini

#. ``/etc/swift/account-server/1.conf``

   .. literalinclude:: /../saio/swift/account-server/1.conf
      :language: ini

#. ``/etc/swift/container-server/1.conf``

   .. literalinclude:: /../saio/swift/container-server/1.conf
      :language: ini

#. ``/etc/swift/object-server/1.conf``

   .. literalinclude:: /../saio/swift/object-server/1.conf
      :language: ini

#. ``/etc/swift/account-server/2.conf``

   .. literalinclude:: /../saio/swift/account-server/2.conf
      :language: ini

#. ``/etc/swift/container-server/2.conf``

   .. literalinclude:: /../saio/swift/container-server/2.conf
      :language: ini

#. ``/etc/swift/object-server/2.conf``

   .. literalinclude:: /../saio/swift/object-server/2.conf
      :language: ini

#. ``/etc/swift/account-server/3.conf``

   .. literalinclude:: /../saio/swift/account-server/3.conf
      :language: ini

#. ``/etc/swift/container-server/3.conf``

   .. literalinclude:: /../saio/swift/container-server/3.conf
      :language: ini

#. ``/etc/swift/object-server/3.conf``

   .. literalinclude:: /../saio/swift/object-server/3.conf
      :language: ini

#. ``/etc/swift/account-server/4.conf``

   .. literalinclude:: /../saio/swift/account-server/4.conf
      :language: ini

#. ``/etc/swift/container-server/4.conf``

   .. literalinclude:: /../saio/swift/container-server/4.conf
      :language: ini

#. ``/etc/swift/object-server/4.conf``

   .. literalinclude:: /../saio/swift/object-server/4.conf
      :language: ini

.. _setup_scripts:

------------------------------------
Setting up scripts for running Swift
------------------------------------

#. Copy the SAIO scripts for resetting the environment::

      mkdir -p $HOME/bin
      cd $HOME/swift/doc; cp saio/bin/* $HOME/bin; cd -
      chmod +x $HOME/bin/*

#. Edit the ``$HOME/bin/resetswift`` script

   The template ``resetswift`` script looks like the following:

   .. literalinclude:: /../saio/bin/resetswift
      :language: bash

   If you are using a loopback device add an environment var to
   substitute ``/dev/sdb1`` with ``/srv/swift-disk``::

      echo "export SAIO_BLOCK_DEVICE=/srv/swift-disk" >> $HOME/.bashrc

   If you did not set up rsyslog for individual logging, remove the ``find
   /var/log/swift...`` line::

      sed -i "/find \/var\/log\/swift/d" $HOME/bin/resetswift


#. Install the sample configuration file for running tests::

      cp $HOME/swift/test/sample.conf /etc/swift/test.conf

   The template ``test.conf`` looks like the following:

   .. literalinclude:: /../../test/sample.conf
      :language: ini

#. Add an environment variable for running tests below::

      echo "export SWIFT_TEST_CONFIG_FILE=/etc/swift/test.conf" >> $HOME/.bashrc

#. Be sure that your ``PATH`` includes the ``bin`` directory::

      echo "export PATH=${PATH}:$HOME/bin" >> $HOME/.bashrc

#. Source the above environment variables into your current environment::

      . $HOME/.bashrc

#. Construct the initial rings using the provided script::

      remakerings

   The ``remakerings`` script looks like the following:

   .. literalinclude:: /../saio/bin/remakerings
      :language: bash

   You can expect the output from this command to produce the following.  Note
   that 3 object rings are created in order to test storage policies and EC in
   the SAIO environment.  The EC ring is the only one with all 8 devices.
   There are also two replication rings, one for 3x replication and another
   for 2x replication, but those rings only use 4 devices:


   .. code-block:: console

      Device d0r1z1-127.0.0.1:6010R127.0.0.1:6010/sdb1_"" with 1.0 weight got id 0
      Device d1r1z2-127.0.0.2:6020R127.0.0.2:6020/sdb2_"" with 1.0 weight got id 1
      Device d2r1z3-127.0.0.3:6030R127.0.0.3:6030/sdb3_"" with 1.0 weight got id 2
      Device d3r1z4-127.0.0.4:6040R127.0.0.4:6040/sdb4_"" with 1.0 weight got id 3
      Reassigned 3072 (300.00%) partitions. Balance is now 0.00.  Dispersion is now 0.00
      Device d0r1z1-127.0.0.1:6010R127.0.0.1:6010/sdb1_"" with 1.0 weight got id 0
      Device d1r1z2-127.0.0.2:6020R127.0.0.2:6020/sdb2_"" with 1.0 weight got id 1
      Device d2r1z3-127.0.0.3:6030R127.0.0.3:6030/sdb3_"" with 1.0 weight got id 2
      Device d3r1z4-127.0.0.4:6040R127.0.0.4:6040/sdb4_"" with 1.0 weight got id 3
      Reassigned 2048 (200.00%) partitions. Balance is now 0.00.  Dispersion is now 0.00
      Device d0r1z1-127.0.0.1:6010R127.0.0.1:6010/sdb1_"" with 1.0 weight got id 0
      Device d1r1z1-127.0.0.1:6010R127.0.0.1:6010/sdb5_"" with 1.0 weight got id 1
      Device d2r1z2-127.0.0.2:6020R127.0.0.2:6020/sdb2_"" with 1.0 weight got id 2
      Device d3r1z2-127.0.0.2:6020R127.0.0.2:6020/sdb6_"" with 1.0 weight got id 3
      Device d4r1z3-127.0.0.3:6030R127.0.0.3:6030/sdb3_"" with 1.0 weight got id 4
      Device d5r1z3-127.0.0.3:6030R127.0.0.3:6030/sdb7_"" with 1.0 weight got id 5
      Device d6r1z4-127.0.0.4:6040R127.0.0.4:6040/sdb4_"" with 1.0 weight got id 6
      Device d7r1z4-127.0.0.4:6040R127.0.0.4:6040/sdb8_"" with 1.0 weight got id 7
      Reassigned 6144 (600.00%) partitions. Balance is now 0.00.  Dispersion is now 0.00
      Device d0r1z1-127.0.0.1:6011R127.0.0.1:6011/sdb1_"" with 1.0 weight got id 0
      Device d1r1z2-127.0.0.2:6021R127.0.0.2:6021/sdb2_"" with 1.0 weight got id 1
      Device d2r1z3-127.0.0.3:6031R127.0.0.3:6031/sdb3_"" with 1.0 weight got id 2
      Device d3r1z4-127.0.0.4:6041R127.0.0.4:6041/sdb4_"" with 1.0 weight got id 3
      Reassigned 3072 (300.00%) partitions. Balance is now 0.00.  Dispersion is now 0.00
      Device d0r1z1-127.0.0.1:6012R127.0.0.1:6012/sdb1_"" with 1.0 weight got id 0
      Device d1r1z2-127.0.0.2:6022R127.0.0.2:6022/sdb2_"" with 1.0 weight got id 1
      Device d2r1z3-127.0.0.3:6032R127.0.0.3:6032/sdb3_"" with 1.0 weight got id 2
      Device d3r1z4-127.0.0.4:6042R127.0.0.4:6042/sdb4_"" with 1.0 weight got id 3
      Reassigned 3072 (300.00%) partitions. Balance is now 0.00.  Dispersion is now 0.00


#. Read more about Storage Policies and your SAIO :doc:`policies_saio`

#. Verify the unit tests run::

      $HOME/swift/.unittests

   Note that the unit tests do not require any swift daemons running.

#. Start the "main" Swift daemon processes (proxy, account, container, and
   object)::

      startmain

   (The "``Unable to increase file descriptor limit.  Running as non-root?``"
   warnings are expected and ok.)

   The ``startmain`` script looks like the following:

   .. literalinclude:: /../saio/bin/startmain
      :language: bash

#. Get an ``X-Storage-Url`` and ``X-Auth-Token``::

      curl -v -H 'X-Storage-User: test:tester' -H 'X-Storage-Pass: testing' http://127.0.0.1:8080/auth/v1.0

#. Check that you can ``GET`` account::

      curl -v -H 'X-Auth-Token: <token-from-x-auth-token-above>' <url-from-x-storage-url-above>

#. Check that ``swift`` command provided by the python-swiftclient package works::

      swift -A http://127.0.0.1:8080/auth/v1.0 -U test:tester -K testing stat

#. Verify the functional tests run::

      $HOME/swift/.functests

   (Note: functional tests will first delete everything in the configured
   accounts.)

#. Verify the probe tests run::

      $HOME/swift/.probetests

   (Note: probe tests will reset your environment as they call ``resetswift``
   for each test.)

----------------
Debugging Issues
----------------

If all doesn't go as planned, and tests fail, or you can't auth, or something
doesn't work, here are some good starting places to look for issues:

#. Everything is logged using system facilities -- usually in ``/var/log/syslog``,
   but possibly in ``/var/log/messages`` on e.g. Fedora -- so that is a good first
   place to look for errors (most likely python tracebacks).
#. Make sure all of the server processes are running.  For the base
   functionality, the Proxy, Account, Container, and Object servers
   should be running.
#. If one of the servers are not running, and no errors are logged to syslog,
   it may be useful to try to start the server manually, for example:
   ``swift-object-server /etc/swift/object-server/1.conf`` will start the
   object server.  If there are problems not showing up in syslog,
   then you will likely see the traceback on startup.
#. If you need to, you can turn off syslog for unit tests. This can be
   useful for environments where ``/dev/log`` is unavailable, or which
   cannot rate limit (unit tests generate a lot of logs very quickly).
   Open the file ``SWIFT_TEST_CONFIG_FILE`` points to, and change the
   value of ``fake_syslog`` to ``True``.
#. If you encounter a ``401 Unauthorized`` when following Step 12 where
   you check that you can ``GET`` account, use ``sudo service memcached status``
   and check if memcache is running. If memcache is not running, start it using
   ``sudo service memcached start``. Once memcache is running, rerun ``GET`` account.

------------
Known Issues
------------

Listed here are some "gotcha's" that you may run into when using or testing your SAIO:

#. fallocate_reserve - in most cases a SAIO doesn't have a very large XFS partition
   so having fallocate enabled and fallocate_reserve set can cause issues, specifically
   when trying to run the functional tests. For this reason fallocate has been turned
   off on the object-servers in the SAIO. If you want to play with the fallocate_reserve
   settings then know that functional tests will fail unless you change the max_file_size
   constraint to something more reasonable then the default (5G). Ideally you'd make
   it 1/4 of your XFS file system size so the tests can pass.