Advanced usage

Custom Runnable Identifier

In some cases, you might have a wrapper as an entry point for the tests, so Avocado will use only the wrapper as test id. For instance, imagine a Makefile with some targets (‘foo’, ‘bar’) and each target is one test. Having a single test suite with a test calling foo, it will make Avocado print something like this:

``` JOB ID : b6e5bdf2c891382bbde7f24e906a168af351154a JOB LOG : ~/avocado/job-results/job-2021-09-24T17.39-b6e5bdf/job.log

(1/1) make: STARTED (1/1) make: PASS (2.72 s)

RESULTS : PASS 1 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 0 JOB HTML : ~/avocado/job-results/job-2021-09-24T17.39-b6e5bdf/results.html JOB TIME : 5.49 s ```

This is happening because Avocado is using the ‘uri’ as identifier with in the current Runnables.

You can change that by setting a custom format with the option runner.identifier_format in you avocado.conf file. For instance:

` [runner] identifier_format = "{uri}-{args[0]}" `

With the above adjustment, running the same suite it will produce something like this:

``` JOB ID : 577b70b079e9a6f325ff3e73fd9b93f80ee7f221 JOB LOG : /home/local/avocado/job-results/job-2021-11-23T13.12-577b70b/job.log

(1/1) “/usr/bin/make-foo”: STARTED (1/1) “/usr/bin/make-foo”: PASS (0.01 s)

RESULTS : PASS 1 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 0 JOB HTML : ~/avocado/job-results/job-2021-11-23T13.12-577b70b/results.html JOB TIME : 0.97 s ```

For the identifier_format you can use any f-string that it will use {uri}, {args} or {kwargs}. By default it will use {uri}.

When using args, since it is a list, you can use in two different ways: “{args}” for the entire list, or “{args[n]}” for a specific element inside this list. The same is valid when using “{kwargs}”. With kwargs, since it is a dictionary, you have to specify a key as index and then the values are used.

For instance if you have a kwargs value named ‘DEBUG’, a valid usage could be: “{kwargs[DEBUG]}” and this will print the current value to this variable (i.e: True or False).


Please, keep in mind this is an experimental feature, and for now you have to use it in combination with documentation.


Also, be aware this feature it is meant to set custom Runnable identifiers strings only. Due some current limitations on hint files, this will not fully solve the ‘external runner’ problem. For that, we have a pending Feature Request

Test Runner Selection

To effectively run a job with tests, Avocado makes use of a well described and pluggable interface. This means that users can choose (and developers can write) their own runners.

Runner choices can be seen by running avocado plugins:

Plugins that run test suites on a job (runners):
nrunner nrunner based implementation of job compliant runner
runner  The conventional test runner

And to select a different test runner, say, the legacy runner:

avocado run --test-runner=runner ...

Wrap executables run by tests

Avocado allows the instrumentation of executables being run by a test in a transparent way. The user specifies a script (“the wrapper”) to be used to run the actual program called by the test.

If the instrumentation script is implemented correctly, it should not interfere with the test behavior. That is, the wrapper should avoid changing the return status, standard output and standard error messages of the original executable.

The user can be specific about which program to wrap (with a shell-like glob), or if that is omitted, a global wrapper that will apply to all programs called by the test.


This feature is implemented as a plugin, that adds the --wrapper option to the avocado run command. For a detailed explanation, please consult the Avocado man page.

Example of a transparent way of running strace as a wrapper:

exec strace -ff -o $AVOCADO_TEST_LOGDIR/strace.log -- $@

This example file is available at examples/wrappers/

To have all programs started by wrapped with ~/bin/

$ avocado run --wrapper ~/bin/ tests/

To have only my-binary wrapped with ~/bin/

$ avocado run --wrapper ~/bin/*my-binary tests/

The following is a working example:

$ avocado run --wrapper examples/wrappers/ /bin/true

The strace file will be located at Avocado log directory, on test-results/1-_bin_true/ subdirectory.


  • You can only set one (global) wrapper. If you need functionality present in two wrappers, you have to combine those into a single wrapper script.
  • Only executables that are run with the avocado.utils.process APIs (and other API modules that make use of it, like are affected by this feature.