Using nose2

Naming Tests

nose2 will look in each directory under the starting directory, unless the configuration modifies the included paths. Within directories and within any Python packages found in the starting directory and any source directories in the starting directory, nose2 will discover test modules and load tests from them. “Test modules” means any modules whose names start with “test”. See the Configuration section for ways to modify searching for tests.

Directories nose2 will look in:

  • Directory that contains an file (a Python package)

  • Directory name that contains “test” after being lowercased.

  • Directory name that is either lib or src

Each of the following test files will be run:

These files will not be run:

Within test modules, nose2 will load tests from unittest.TestCase subclasses, and from test functions (functions whose names begin with “test”).

Running Tests

In the simplest case, go to the directory that includes your project source and run nose2 there:


This will discover tests in packages and test directories under that directory, load them, and run them, then output something like:

Ran 77 tests in 1.897s


To change the place discovery starts, or to change the top-level importable directory of the project, use the -s and -t options.

-s START_DIR, --start-dir START_DIR

Directory to start discovery. Defaults to the current working directory. This directory is where nose2 will start looking for tests.

-t TOP_LEVEL_DIRECTORY, --top-level-directory TOP_LEVEL_DIRECTORY, --project-directory TOP_LEVEL_DIRECTORY

Top-level directory of the project. Defaults to the starting directory. This is the directory containing importable modules and packages, and is always prepended to sys.path before test discovery begins.

Specifying Tests to Run

Pass test names to nose2 on the command line to run individual test modules, classes, or tests.

A test name consists of a python object part and, for generator or parameterized tests, an argument part. The python object part is a dotted name, such as pkg1.tests.test_things.SomeTests.test_ok. The argument part is separated from the python object part by a colon (“:”) and specifies the index of the generated test to select, starting from 1. For example, pkg1.test.test_things.test_params_func:1 would select the first test generated from the parameterized test test_params_func.

Plugins may provide other means of test selection.

Running Tests with python test

nose2 supports distribute/setuptools’ python test standard for running tests. To use nose2 to run your package’s tests, add the following to your


(Not literally. Don’t put the ‘…’ parts in.)

Two warnings about running tests this way.

One: because the setuptools test command is limited, nose2 returns a “test suite” that actually takes over the test running process completely, bypassing the test result and test runner that call it. This may be incompatible with some packages.

Two: because the command line arguments to the test command may not match up properly with nose2’s arguments, the nose2 instance started by the collector does not accept any command line arguments. This means that it always runs all tests, and that you cannot configure plugins on the command line when running tests this way. As a workaround, when running under the test command, nose2 will read configuration from setup.cfg if it is present, in addition to unittest.cfg and nose2.cfg. This enables you to put configuration specific to the setuptools test command in setup.cfg – for instance to activate plugins that you would otherwise activate via the command line.

Getting Help


nose2 -h

to get help for nose2 itself and all loaded plugins.

usage: nose2 [-s START_DIR] [-t TOP_LEVEL_DIRECTORY] [--config [CONFIG]]
             [--no-user-config] [--no-plugins] [--verbose] [--quiet] [-B] [-D]
             [--collect-only] [--log-capture] [-P] [-h]
             [testNames [testNames ...]]

positional arguments:

optional arguments:
  -s START_DIR, --start-dir START_DIR
                        Directory to start discovery ('.' default)
  -t TOP_LEVEL_DIRECTORY, --top-level-directory TOP_LEVEL_DIRECTORY, --project-directory TOP_LEVEL_DIRECTORY
                        Top level directory of project (defaults to start dir)
  --config [CONFIG], -c [CONFIG]
                        Config files to load, if they exist. ('unittest.cfg'
                        and 'nose2.cfg' in start directory default)
  --no-user-config      Do not load user config files
  --no-plugins          Do not load any plugins. Warning: nose2 does not do
                        anything if no plugins are loaded
  --verbose, -v
  -h, --help            Show this help message and exit

plugin arguments:
  Command-line arguments added by plugins:

  -B, --output-buffer   Enable output buffer
  -D, --debugger        Enter pdb on test fail or error
  --collect-only        Collect but do not run tests. With '-v', this will output test names
  --log-capture         Enable log capture
  -P, --print-hooks     Print names of hooks in order of execution