193
193
<http://babune.ladeuil.net:24842/>. (Babune = Bazaar Buildbot Network.)
196
Running tests in parallel
197
-------------------------
199
Bazaar can use subunit to spawn multiple test processes. There is
200
slightly more chance you will hit ordering or timing-dependent bugs but
203
$ ./bzr selftest --parallel=fork
205
Note that you will need the Subunit library
206
<https://launchpad.net/subunit/> to use this, which is in
207
``python-subunit`` on Ubuntu.
210
Running tests from a ramdisk
211
----------------------------
213
The tests create and delete a lot of temporary files. In some cases you
214
can make the test suite run much faster by running it on a ramdisk. For
218
$ sudo mount -t tmpfs none /ram
219
$ TMPDIR=/ram ./bzr selftest ...
221
You could also change ``/tmp`` in ``/etc/fstab`` to have type ``tmpfs``,
222
if you don't mind possibly losing other files in there when the machine
223
restarts. Add this line (if there is none for ``/tmp`` already)::
225
none /tmp tmpfs defaults 0 0
227
With a 6-core machine and ``--parallel=fork`` using a tmpfs doubles the
228
test execution speed.
329
294
We make selective use of doctests__. In general they should provide
330
295
*examples* within the API documentation which can incidentally be tested. We
331
296
don't try to test every important case using doctests |--| regular Python
332
tests are generally a better solution. That is, we just use doctests to make
333
our documentation testable, rather than as a way to make tests. Be aware that
334
doctests are not as well isolated as the unit tests, if you need more
335
isolation, you're likely want to write unit tests anyway if only to get a
336
better control of the test environment.
297
tests are generally a better solution. That is, we just use doctests to
298
make our documentation testable, rather than as a way to make tests.
338
300
Most of these are in ``bzrlib/doc/api``. More additions are welcome.
340
302
__ http://docs.python.org/lib/module-doctest.html
342
There is an `assertDoctestExampleMatches` method in
343
`bzrlib.tests.TestCase` that allows you to match against doctest-style
344
string templates (including ``...`` to skip sections) from regular Python
351
``bzrlib/tests/script.py`` allows users to write tests in a syntax very
352
close to a shell session, using a restricted and limited set of commands
353
that should be enough to mimic most of the behaviours.
308
``bzrlib/tests/script.py`` allows users to write tests in a syntax very close to a shell session,
309
using a restricted and limited set of commands that should be enough to mimic
310
most of the behaviours.
355
312
A script is a set of commands, each command is composed of:
445
You can run files containing shell-like scripts with::
447
$ bzr test-script <script>
449
where ``<script>`` is the path to the file containing the shell-like script.
451
395
The actual use of ScriptRunner within a TestCase looks something like
454
from bzrlib.tests import script
456
def test_unshelve_keep(self):
458
script.run_script(self, '''
460
$ bzr shelve -q --all -m Foo
463
$ bzr unshelve -q --keep
470
You can also test commands that read user interaction::
472
def test_confirm_action(self):
473
"""You can write tests that demonstrate user confirmation"""
474
commands.builtin_command_registry.register(cmd_test_confirm)
475
self.addCleanup(commands.builtin_command_registry.remove, 'test-confirm')
478
2>Really do it? [y/n]:
483
To avoid having to specify "-q" for all commands whose output is
484
irrelevant, the run_script() method may be passed the keyword argument
485
``null_output_matches_anything=True``. For example::
487
def test_ignoring_null_output(self):
490
$ bzr ci -m 'first revision' --unchanged
493
""", null_output_matches_anything=True)
398
def test_unshelve_keep(self):
401
sr.run_script(self, '''
403
$ bzr shelve --all -m Foo
406
$ bzr unshelve --keep
496
414
Import tariff tests
497
415
-------------------
512
430
dependencies and only needed for particular cases. If they're loaded in
513
431
other cases then bzr may break for people who don't have those modules.
515
`test_import_tariff` allows us to check that removal of imports doesn't
433
`test_import_tarrif` allows us to check that removal of imports doesn't
518
436
This is done by running the command in a subprocess with
519
``PYTHON_VERBOSE=1``. Starting a whole Python interpreter is pretty slow,
520
so we don't want exhaustive testing here, but just enough to guard against
521
distinct fixed problems.
437
``--profile-imports``. Starting a whole Python interpreter is pretty
438
slow, so we don't want exhaustive testing here, but just enough to guard
439
against distinct fixed problems.
523
441
Assertions about precisely what is loaded tend to be brittle so we instead
524
442
make assertions that particular things aren't loaded.
839
741
whether a test should be added for that particular implementation,
840
742
or for all implementations of the interface.
744
The multiplication of tests for different implementations is normally
745
accomplished by overriding the ``load_tests`` function used to load tests
746
from a module. This function typically loads all the tests, then applies
747
a TestProviderAdapter to them, which generates a longer suite containing
748
all the test variations.
842
750
See also `Per-implementation tests`_ (above).
845
Test scenarios and variations
846
-----------------------------
848
756
Some utilities are provided for generating variations of tests. This can
849
757
be used for per-implementation tests, or other cases where the same test
854
762
values to which the test should be applied. The test suite should then
855
763
also provide a list of scenarios in which to run the tests.
857
A single *scenario* is defined by a `(name, parameter_dict)` tuple. The
858
short string name is combined with the name of the test method to form the
859
test instance name. The parameter dict is merged into the instance's
864
load_tests = load_tests_apply_scenarios
866
class TestCheckout(TestCase):
868
scenarios = multiply_scenarios(
869
VaryByRepositoryFormat(),
873
The `load_tests` declaration or definition should be near the top of the
874
file so its effect can be seen.
765
Typically ``multiply_tests_from_modules`` should be called from the test
766
module's ``load_tests`` function.
977
869
Please see bzrlib.treebuilder for more details.
982
PreviewTrees are based on TreeTransforms. This means they can represent
983
virtually any state that a WorkingTree can have, including unversioned files.
984
They can be used to test the output of anything that produces TreeTransforms,
985
such as merge algorithms and revert. They can also be used to test anything
986
that takes arbitrary Trees as its input.
990
# Get an empty tree to base the transform on.
991
b = self.make_branch('.')
992
empty_tree = b.repository.revision_tree(_mod_revision.NULL_REVISION)
993
tt = TransformPreview(empty_tree)
994
self.addCleanup(tt.finalize)
995
# Empty trees don't have a root, so add it first.
996
root = tt.new_directory('', ROOT_PARENT, 'tree-root')
997
# Set the contents of a file.
998
tt.new_file('new-file', root, 'contents', 'file-id')
999
preview = tt.get_preview_tree()
1000
# Test the contents.
1001
self.assertEqual('contents', preview.get_file_text('file-id'))
1003
PreviewTrees can stack, with each tree falling back to the previous::
1005
tt2 = TransformPreview(preview)
1006
self.addCleanup(tt2.finalize)
1007
tt2.new_file('new-file2', tt2.root, 'contents2', 'file-id2')
1008
preview2 = tt2.get_preview_tree()
1009
self.assertEqual('contents', preview2.get_file_text('file-id'))
1010
self.assertEqual('contents2', preview2.get_file_text('file-id2'))
1013
Temporarily changing state
1014
~~~~~~~~~~~~~~~~~~~~~~~~~~
1016
If your test needs to temporarily mutate some global state, and you need
1017
it restored at the end, you can say for example::
1019
self.overrideAttr(osutils, '_cached_user_encoding', 'latin-1')
1021
Temporarily changing environment variables
1022
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1024
If yout test needs to temporarily change some environment variable value
1025
(which generally means you want it restored at the end), you can use::
1027
self.overrideEnv('BZR_ENV_VAR', 'new_value')
1029
If you want to remove a variable from the environment, you should use the
1030
special ``None`` value::
1032
self.overrideEnv('PATH', None)
1034
If you add a new feature which depends on a new environment variable, make
1035
sure it behaves properly when this variable is not defined (if applicable) and
1036
if you need to enforce a specific default value, check the
1037
``TestCase._cleanEnvironment`` in ``bzrlib.tests.__init__.py`` which defines a
1038
proper set of values for all tests.
1043
Our base ``TestCase`` class provides an ``addCleanup`` method, which
1044
should be used instead of ``tearDown``. All the cleanups are run when the
1045
test finishes, regardless of whether it passes or fails. If one cleanup
1046
fails, later cleanups are still run.
1048
(The same facility is available outside of tests through
1049
``bzrlib.cleanup``.)
1055
Generally we prefer automated testing but sometimes a manual test is the
1056
right thing, especially for performance tests that want to measure elapsed
1057
time rather than effort.
1059
Simulating slow networks
1060
------------------------
1062
To get realistically slow network performance for manually measuring
1063
performance, we can simulate 500ms latency (thus 1000ms round trips)::
1065
$ sudo tc qdisc add dev lo root netem delay 500ms
1067
Normal system behaviour is restored with ::
1069
$ sudo tc qdisc del dev lo root
1071
A more precise version that only filters traffic to port 4155 is::
1073
tc qdisc add dev lo root handle 1: prio
1074
tc qdisc add dev lo parent 1:3 handle 30: netem delay 500ms
1075
tc qdisc add dev lo parent 30:1 handle 40: prio
1076
tc filter add dev lo protocol ip parent 1:0 prio 3 u32 match ip dport 4155 0xffff flowid 1:3 handle 800::800
1077
tc filter add dev lo protocol ip parent 1:0 prio 3 u32 match ip sport 4155 0xffff flowid 1:3 handle 800::801
1079
and to remove this::
1081
tc filter del dev lo protocol ip parent 1: pref 3 u32
1082
tc qdisc del dev lo root handle 1:
1084
You can use similar code to add additional delay to a real network
1085
interface, perhaps only when talking to a particular server or pointing at
1086
a VM. For more information see <http://lartc.org/>.
1089
872
.. |--| unicode:: U+2014
1092
vim: ft=rst tw=74 ai et sw=4
added
removed
doc/developers/testing.txt
