Run tests and test documentation

Contributing includes testing your changes. If you change the Docker code, you may need to add a new test or modify an existing one. Your contribution could even be adding tests to Docker. For this reason, you need to know a little about Docker’s test infrastructure.

Many contributors contribute documentation only. Or, a contributor makes a code contribution that changes how Docker behaves and that change needs documentation. For these reasons, you also need to know how to build, view, and test the Docker documentation.

This section describes tests you can run in the dry-run-test branch of your Docker fork. If you have followed along in this guide, you already have this branch. If you don’t have this branch, you can create it or simply use another of your branches.

Understand testing at Docker

Docker tests use the Go language’s test framework. In this framework, files whose names end in _test.go contain test code; you’ll find test files like this throughout the Docker repo. Use these files for inspiration when writing your own tests. For information on Go’s test framework, see Go’s testing package documentation and the go test help.

You are responsible for unit testing your contribution when you add new or change existing Docker code. A unit test is a piece of code that invokes a single, small piece of code ( unit of work ) to verify the unit works as expected.

Depending on your contribution, you may need to add integration tests. These are tests that combine two or more work units into one component. These work units each have unit tests and then, together, integration tests that test the interface between the components. The integration and integration-cli directories in the Docker repository contain integration test code.

Testing is its own specialty. If you aren’t familiar with testing techniques, there is a lot of information available to you on the Web. For now, you should understand that, the Docker maintainers may ask you to write a new test or change an existing one.

Run tests on your local host

Before submitting a pull request with a code change, you should run the entire Docker Engine test suite. The Makefile contains a target for the entire test suite. The target’s name is simply test. The Makefile contains several targets for testing:

Target What this target does
test Run the unit, integration and docker-py tests.
test-unit Run just the unit tests.
test-integration-cli Run the test for the integration command line interface.
test-docker-py Run the tests for Docker API client.

Running the entire test suite on your current repository can take a half an hour or more. To run the test suite, do the following:

  1. Open a terminal on your local host.

  2. Change to the root your Docker repository.

    $ cd docker-fork
  3. Make sure you are in your development branch.

    $ git checkout dry-run-test
  4. Run the make test command.

    $ make test

    This command does several things, it creates a container temporarily for testing. Inside that container, the make:

    • creates a new binary
    • cross-compiles all the binaries for the various operating systems
    • runs all the tests in the system

    It can take approximate one hour to run all the tests. The time depends on your host performance. The default timeout is 60 minutes, which is defined in hack/${TIMEOUT:=60m}). You can modify the timeout value on the basis of your host performance. When they complete successfully, you see the output concludes with something like this:

    PASS: docker_cli_pull_test.go:133: DockerHubPullSuite.TestPullClientDisconnect  1.127s
    PASS: docker_cli_pull_test.go:16: DockerHubPullSuite.TestPullFromCentralRegistry    1.049s
    PASS: docker_cli_pull_test.go:65: DockerHubPullSuite.TestPullFromCentralRegistryImplicitRefParts    9.795s
    PASS: docker_cli_pull_test.go:42: DockerHubPullSuite.TestPullNonExistingImage   2.158s
    PASS: docker_cli_pull_test.go:92: DockerHubPullSuite.TestPullScratchNotAllowed  0.044s
    OK: 918 passed, 13 skipped
    coverage: 72.9% of statements
    ok    1638.553s
    ---> Making bundle: .integration-daemon-stop (in bundles/1.9.0-dev/test-integration-cli)
    ++++ cat bundles/1.9.0-dev/test-integration-cli/
    +++ kill 9453
    +++ /etc/init.d/apparmor stop
     * Clearing AppArmor profiles cache
    All profile caches have been cleared, but no profiles have been unloaded.
    Unloading profiles will leave already running processes permanently
    unconfined, which can lead to unexpected situations.
    To set a process to complain mode, use the command line tool
    'aa-complain'. To really tear down all profiles, run the init script
    with the 'teardown' option."
    ---> Making bundle: test-docker-py (in bundles/1.9.0-dev/test-docker-py)
    ---> Making bundle: .integration-daemon-start (in bundles/1.9.0-dev/test-docker-py)
    +++ /etc/init.d/apparmor start
     * Starting AppArmor profiles
    Skipping profile in /etc/apparmor.d/disable: usr.sbin.rsyslogd
    +++ exec docker daemon --debug --host unix:///go/src/ --storage-driver overlay --exec-driver native --pidfile bundles/1.9.0-dev/test-docker-py/ --userland-proxy=true
    Ran 68 tests in 79.135s

Run targets inside a development container

If you are working inside a Docker development container, you use the hack/ script to run tests. The hack/ script doesn’t have a single target that runs all the tests. Instead, you provide a single command line with multiple targets that does the same thing.

Try this now.

  1. Open a terminal and change to the docker-fork root.

  2. Start a Docker development image.

    If you are following along with this guide, you should have a dry-run-test image.

    $ docker run --privileged --rm -ti -v `pwd`:/go/src/ dry-run-test /bin/bash
  3. Run the tests using the hack/ script.

    root@5f8630b873fe:/go/src/ hack/ dynbinary binary cross test-unit test-integration-cli test-docker-py

    The tests run just as they did within your local host.

    Of course, you can also run a subset of these targets too. For example, to run just the unit tests:

    root@5f8630b873fe:/go/src/ hack/ dynbinary binary cross test-unit

    Most test targets require that you build these precursor targets first: dynbinary binary cross

Run unit tests

We use golang standard testing package or gocheck for our unit tests.

You can use the TESTDIRS environment variable to run unit tests for a single package.

$ TESTDIRS='opts' make test-unit

You can also use the TESTFLAGS environment variable to run a single test. The flag’s value is passed as arguments to the go test command. For example, from your local host you can run the TestBuild test with this command:

$ TESTFLAGS=' ^TestValidateIPAddress$' make test-unit

On unit tests, it’s better to use TESTFLAGS in combination with TESTDIRS to make it quicker to run a specific test.

$ TESTDIRS='opts' TESTFLAGS=' ^TestValidateIPAddress$' make test-unit

Run integration tests

We use gocheck for our integration-cli tests. You can use the TESTFLAGS environment variable to run a single test. The flag’s value is passed as arguments to the go test command. For example, from your local host you can run the TestBuild test with this command:

$ TESTFLAGS='-check.f DockerSuite.TestBuild*' make test-integration-cli

To run the same test inside your Docker development container, you do this:

root@5f8630b873fe:/go/src/ TESTFLAGS='-check.f TestBuild*' hack/ binary test-integration-cli

Test the Windows binary against a Linux daemon

This explains how to test the Windows binary on a Windows machine set up as a development environment. The tests will be run against a docker daemon running on a remote Linux machine. You’ll use Git Bash that came with the Git for Windows installation. Git Bash, just as it sounds, allows you to run a Bash terminal on Windows.

  1. If you don’t have one open already, start a Git Bash terminal.

    Git Bash

  2. Change to the docker source directory.

    $ cd /c/gopath/src/
  3. Set DOCKER_REMOTE_DAEMON as follows:

  4. Set DOCKER_TEST_HOST to the tcp://IP_ADDRESS:2376 value; substitute your Linux machines actual IP address. For example:

    $ export DOCKER_TEST_HOST=tcp://
  5. Make the binary and run the tests:

    $ hack/ binary test-integration-cli

Some tests are skipped on Windows for various reasons. You can see which tests were skipped by re-running the make and passing in the TESTFLAGS='-test.v' value. For example

    $ TESTFLAGS='-test.v' hack/ binary test-integration-cli

Should you wish to run a single test such as one with the name
'TestExample', you can pass in `TESTFLAGS='-check.f TestExample'`. For

    $TESTFLAGS='-check.f TestExample' hack/ binary test-integration-cli

You can now choose to make changes to the Docker source or the tests. If you make any changes just run these commands again.

Build and test the documentation

The Docker documentation source files are under docs. The content is written using extended Markdown. We use the static generator MkDocs to build Docker’s documentation. Of course, you don’t need to install this generator to build the documentation, it is included with container.

You should always check your documentation for grammar and spelling. The best way to do this is with an online grammar checker.

When you change a documentation source file, you should test your change locally to make sure your content is there and any links work correctly. You can build the documentation from the local host. The build starts a container and loads the documentation into a server. As long as this container runs, you can browse the docs.

  1. In a terminal, change to the root of your docker-fork repository.

    $ cd ~/repos/docker-fork
  2. Make sure you are in your feature branch.

    $ git status
    On branch dry-run-test
    Your branch is up-to-date with 'origin/dry-run-test'.
    nothing to commit, working directory clean
  3. Build the documentation.

    $ make docs

    When the build completes, you’ll see a final output message similar to the following:

    Successfully built ee7fe7553123
    docker run --rm -it  -e AWS_S3_BUCKET -e NOCACHE -p 8000:8000 "docker-docs:dry-run-test" mkdocs serve
    Running at:
    Live reload enabled.
    Hold ctrl+c to quit.
  4. Enter the URL in your browser.

    If you are using Docker Machine, replace the default localhost address ( with your DOCKERHOST value. You can get this value at any time by entering docker-machine ip <machine-name> at the command line.

  5. Once in the documentation, look for the red notice to verify you are seeing the correct build.

    Beta documentation

  6. Navigate to your new or changed document.

  7. Review both the content and the links.

  8. Return to your terminal and exit out of the running documentation container.

Where to go next

Congratulations, you have successfully completed the basics you need to understand the Docker test framework. In the next steps, you use what you have learned so far to contribute to Docker by working on an issue.