selftests: tc-testing: add "depends_on" property to skip tests

currently, users can skip individual test cases by means of writing

"skip": "yes"

in the scenario file. Extend this functionality, introducing 'dependsOn':
it's optional property like "skip", but the value contains a command (for
example, a probe on iproute2 to check if it supports a specific feature).
If such property is present, tdc executes that command and skips the test
when the return value is non-zero.

Reviewed-by: Pedro Tammela <pctammela@mojatatu.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tc-testing: Allow test cases to be skipped

By adding a check for an optional key/value pair to the test case
data, individual test cases may be skipped to prevent tdc from
aborting a test run due to setup or teardown failure.

If a test case is skipped, it will still appear in the results
output to allow for a consistent number of executed tests in each
run. However, the test will be marked as skipped.

This support for skipping extends to any plugins that may generate
additional results for each executed test.

Signed-off-by: Lucas Bates <lucasb@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools: tc-testing: Command line parms

Separate the functionality of the command line parameters into "selection"
parameters, "action" parameters and other parameters.

"Selection" parameters are for choosing which tests on which to act.
"Action" parameters are for choosing what to do with the selected tests.
"Other" parameters are for global effect (like "help" or "verbose").

With this commit, we add the ability to name a directory as another
selection mechanism. We can accumulate a number of tests by directory,
file, category, or even by test id, instead of being constrained to
run all tests in one collection or just one test.

Signed-off-by: Brenda J. Butler <bjb@mojatatu.com>
Acked-by: Lucas Bates <lucasb@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tc-testing: very simple example test cases

As part of documentation, supply some very simple test cases
to illustrate how test cases work. One test case shows
commands in the setup, command, verify and teardown stages.
Other test cases show how to have a working test case that
does not have commands in the setup, verify and/or teardown
stages.

Specifically, the command lists for setup and teardown can
be empty. And the verify command must have a command, but
it can be /bin/true. The regex must have a string, we
recommend a single space, and the count of matches must be
zero if you do not want to use the match feature of verify.
Verify will always look for a return code of success (0)
so we give /bin/true when we do not want to make a check
there.

Also, update the documentation for testcases to be more
specific in the cases of:

- accepting non-success return codes in setup and
teardown stages
- how to write the test when no setup, teardown
and/or verify are desired.

To run the example test cases:

$ sudo -E ./tdc.py -f creating-testcases/example.json -l
1f: (example) simple test to test framework
2f: (example) simple test, no need for verify
3f: (example) simple test, no need for setup or teardown (or verify)
$ sudo -E ./tdc.py -f creating-testcases/example.json
Test 1f: simple test to test framework
Test 2f: simple test, no need for verify
Test 3f: simple test, no need for setup or teardown (or verify)
All test results:

1..3
ok 1 1f simple test to test framework
ok 2 2f simple test, no need for verify
ok 3 3f simple test, no need for setup or teardown (or verify)

$

Signed-off-by: Brenda J. Butler <bjb@mojatatu.com>
Acked-by: Lucas Bates <lucasb@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests: Introduce tc testsuite

Add the beginnings of a testsuite for tc functionality in the kernel.
These are a series of unit tests that use the tc executable and verify
the success of those commands by checking both the exit codes and the
output from tc's 'show' operation.

To run the tests:
# cd tools/testing/selftests/tc-testing
# sudo ./tdc.py

You can specify the tc executable to use with the -p argument on the command
line or editing the 'TC' variable in tdc_config.py. Refer to the README for
full details on how to run.

The initial complement of test cases are limited mostly to tc actions. Test
cases are most welcome; see the creating-testcases subdirectory for help
in creating them.

Signed-off-by: Lucas Bates <lucasb@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>