By default, your top level devenv/bin directory will contain a script called openmdao_test that uses a Python package called nose to run all of the unit tests for any package that you specify. For example, to run the full set of openmdao unit tests, type:


which should generate output something like this:

Ran 293 tests in 142.846s


To run unit tests for a package only, for example openmdao.main, type:

openmdao_test openmdao.main

To get a list of options available with openmdao_test, type openmdao_test --help from the devenv directory. Since the openmdao_test script uses the nose testing framework internally, all options available when running nosetests should also be available when using openmdao_test.

Test Coverage

A Python package called coverage, which is accessible through openmdao_test, makes it easy to determine if your tests cover every line of code in your source files. To get a coverage report for the openmdao package, go to the devenv directory and type the following:

openmdao_test openmdao --with-coverage --cover-package=openmdao

The report should look something like this:

Name                                Stmts   Exec  Cover   Missing
openmdao                                5      0     0%   2-6
openmdao.lib                            0      0   100%
openmdao.lib.components                 0      0   100%
openmdao.lib.drivers                    0      0   100%
openmdao.lib.drivers.conmindriver     183    179    97%   149, 233-234, 271
openmdao.lib.factories                  0      0   100%
openmdao.lib.variables                  0      0   100%
openmdao.main                           6      3    50%   5-7
openmdao.main.arrayvar                 48     47    97%   32
openmdao.main.assembly                103    101    98%   95, 129
openmdao.main.component                47     41    87%   58, 92, 99, 106, 121, 142
openmdao.main.constants                 4      4   100%
openmdao.main.constraint               44     43    97%   24
openmdao.main.container               201    185    92%   22-24, 138, 156, 166, 253-254, 276-277, 337, 340, 356, 359, 367-368
openmdao.main.containervar             50     29    58%   29, 38-43, 49-55, 66-72, 82
openmdao.main.driver                   18     15    83%   35, 40-41
openmdao.main.exceptions                5      5   100%
openmdao.main.expreval                122    115    94%   27, 32, 36, 40, 85, 177, 222
openmdao.main.factory                   6      5    83%   25
openmdao.main.factorymanager           21     16    76%   28, 33-37
openmdao.main.float                    70     54    77%   38-41, 49-53, 58-61, 69-73, 105, 120
openmdao.main.hierarchy                49     46    93%   34, 40, 59
openmdao.main.importfactory            28     25    89%   47-49
openmdao.main.int                      42     24    57%   31-34, 39-46, 51-54, 59-66
openmdao.main.interfaces               54     54   100%
openmdao.main.logger                    9      9   100%
openmdao.main.pkg_res_factory          61     59    96%   88, 114
openmdao.main.string                   42     28    66%   31-34, 42-46, 51-54, 62-66
openmdao.main.stringlist               56     40    71%   31-34, 42-46, 51-54, 62-66, 92, 95
openmdao.main.tarjan                   58     26    44%   52-71, 78-96, 100
openmdao.main.variable                138    113    81%   22, 54, 65, 73, 101-104, 112, 117, 129, 141, 184, 202, 227, 263, 265-270, 276, 282-285, 289-290
openmdao.main.vartypemap               19     17    89%   42-45
openmdao.main.workflow                 56     35    62%   30, 43, 56, 61-75, 79, 86-88, 92
TOTAL                                1545   1318    85%
Ran 82 tests in 5.678s


The numbers in the Missing column indicate lines or ranges of lines that are not covered by the current set of tests.

If you edit source code, the coverage data may become inaccurate, so you should clear the coverage database by issuing the following command:

openmdao_test openmdao --cover-erase

Note that the coverage package is not included with openmdao, so to use it you’ll have to install it in your openmdao environment like this:

easy_install coverage

Adding New Tests

Generally, you should write your tests using Python’s unittest framework if possible, although the nose package is able to find and run tests that do not use unittest.

The following is a simple example of a unit test written using the unittest framework.

import unittest

class TestSomeFunctions(unittest.TestCase):

    def setUp(self):
        # put setup code here. It will run at the beginning of each
        # test function (function with name that starts with 'test')

    def tearDown(self):
        # put code here that you want to be run after each test function
        # is completed

    def testfunct1(self):
        # a test function

    def test_some_stuff(self):
        # another test function

if __name__ == '__main__':

The unittest.TestCase class provides a number of functions to test output during a test function. For example:

Test will fail if expr does not evaluate to True.
Test will fail if val1 != val2
Test will fail if val1 == val2
Test will fail if val1 differs from val2 by more than a small number of decimal places.
Test will fail and display the given message.

Often in a test you will want to make sure that a specific exception is raised when a certain thing happens, and usually you want to verify that the error message contains certain information. The unittest framework provides an assertRaises function that does part of this job, but it does not allow you to check the error message. So the preferred way to test exceptions is shown in the code below. In this example, we will assume that the exception we are interested in is a ValueError. Note that we would place our test function inside of our unittest.TestCase derived class.

def test_myexception(self):
        # perform action here that should raise exception
    except ValueError, err:
        self.assertEqual(str(err), "this should be my expected error message")
        self.fail('expected a ValueError')

Note that the else block after the except is important because we want the test to fail if no exception is raised. Without the else block, the test would pass if no exception were raised.

Test File Locations

Unit tests are typically placed in a test subdirectory within the directory where the source code being tested is located. For example, the test files for openmdao.main are located in openmdao.main/src/openmdao/main/test.

Testing Code in the Documentation

The OpenMDAO documentation includes quite a few examples of Python code. These examples illustrate how to use features of the OpenMDAO API as well as how to develop new components and plugins. Thus, it is imperative that any code examples included in the documentation (particularly the User Guide and the Developer Guide) be tested to ensure that the code is error-free.

Fortunately, there are tools built into the Sphinx reStructuredText processor that make the process of testing code samples much easier. Sphinx includes a builder called doctest as a plugin in its standard library. Instead of building a readable document as is done by the HTML builder, the doctest builder scans the documentation files for code blocks and tests them.

Two types of code examples are found in the documentation. The first type is a block of code as would be found in a Python script:

from openmdao.examples.enginedesign.engine import Engine
my_engine = Engine("new_engine")

The second type of code example is a copy of an interactive shell session:

>>> print "Hello!"

Both of these types of code samples must be tested, although the way to accomplish this differs slightly in each case. Unlike the doctest module built into Python, which can handle only shell session blocks, the doctest builder included with Sphinx can handle both of these code sample types.

Testing Code Blocks

The doctest builder in Sphinx provides a flexible environment to easily and effectively test blocks of code using a set of directives. The test code directive is used to mark a block of text that should be tested and treated as Python code. It is not always possible to execute a standalone block of Python code without first executing some preliminary code containing any prerequisites (e.g., imports.) The testsetup block makes it possible to run the preliminary code. This block is hidden by default, so it does not show up in the generated HTML documentation. Additionally, the testoutput block should include any output that is generated by the testcode block so that it can be tested.

A simple example of how to implement these three blocks is shown here:

.. testsetup:: Group1

# Put any preliminary code that needs to run before the sample code.
# This block does not show up when Sphinx builds the HTML

.. testcode:: Group1

# This is the sample code that shows up in your docs

.. testoutput:: Group1

# If your code block outputs anything when executed, then that output
# needs to go in this block.

Group1 is a label that we’ve given this set of blocks. You can have multiple labels in your documents. Also, the testsetup and testoutput blocks are both optional. Some code examples don’t need either. You can have multiple testcode blocks for a single testsetup block. The environment is preserved across all of the testcode blocks in a given group, so that the code executed in the first testcode block in Group1 affects all later blocks in Group1.

The label is optional; when not explicitly defined, default is used.

The doctest directive is used to specify blocks of interactive shell Python code. If the directive is omitted, the doctest builder can often find the Python blocks by itself, but it is still a good idea to include it so that you can control the environment.

.. doctest:: Group2

>>> # This code is tested

The doctest blocks share their workspace in a similar manner as the testcode blocks. Other options can be enabled for the doctest blocks, but so far the default ones have been fine.

More details on using the doctest builder can be found here: http://sphinx.pocoo.org/ext/doctest.html

Including Code Straight from the Source

At times it is more efficient to directly include code from a source file. The built-in Sphinx directive that enables this is called the literalinclude block:

.. literalinclude:: ../../openmdao.examples/openmdao/examples/enginedesign/engine_wrap_c.py
   :start-after: engine_weight = 0.0
   :end-before: # end engine.py
   :language: python

The first line contains the relative path location of the file that is to be included. Since you rarely want to include an entire file, the options start-after and end-before can be used to define the bookends that bound the block of text to be included.

Sometimes, it makes more sense to grab specific lines from a file. This can also be done with the lines option.

.. literalinclude:: ../../openmdao.examples/openmdao/examples/enginedesign/engine_wrap_c.py
   :lines: 3,7-12,45
   :language: python

More details on the literalinclude directive can be found at http://sphinx.pocoo.org/markup/code.html.

Helpful Tips

  • Tracebacks don’t have to be accurately reproduced (and they can’t be anyway). Handle these by replacing the traceback with ellipses:

    >>> my_engine.set("RPM",7500)
    Traceback (most recent call last):
    TraitError: Trait 'RPM' must be a float in the range [1000.0, 6000.0] but a value
    of 7500 <type 'int'> was specified.
  • Indentation is not preserved between code blocks in the same group. This means that all functions and class definitions effectively close when the block ends. If you need to show code from the middle of a function class, you may have to get creative in what you place in your testsetup block (e.g., defining self as something.)

  • Take care to assure that each block of code is being tested. One way to do this is to purposefully introduce an error into a block to verify that it is caught.

  • Be wary of including code by line number. If the source file is changed and lines are added or removed, then the included code might not be what was intended.

  • To include a numerical example in a doctest block, you can use ellipses to match the output to a specific tolerance. For example, this block of text passes:

    >>> import numpy
    >>> numpy.pi
  • Sphinx automatically generates syntax highlighting for the code block, but it can get confused if you mix tabs and spaces.

Running the Tests

The doctests are automatically run whenever you run openmdao_test, but you can also run them separately. In an active openmdao virtual environment, type:


This command builds the documents and then runs the doctests. If the test was successful, you should see output similar to the following:

Doctest summary
  156 tests
    0 failures in tests
    0 failures in setup code
build succeeded.

If any tests fail, they will be noted in this summary, and specific tracebacks will be given for each failure earlier in the output.


If you make changes to the docs, rebuild the documentation by running openmdao_build_docs and display them by typing openmdao_docs.