108
96
For further information, see http://bazaar-vcs.org/BzrDevelopment.
113
Preparing a Sandbox for Making Changes to Bazaar
114
================================================
116
Bazaar supports many ways of organising your work. See
117
http://bazaar-vcs.org/SharedRepositoryLayouts for a summary of the
118
popular alternatives.
120
Of course, the best choice for you will depend on numerous factors:
121
the number of changes you may be making, the complexity of the changes, etc.
122
As a starting suggestion though:
124
* create a local copy of the main development branch (bzr.dev) by using
127
bzr branch http://bazaar-vcs.org/bzr/bzr.dev/ bzr.dev
129
* keep your copy of bzr.dev prestine (by not developing in it) and keep
130
it up to date (by using bzr pull)
132
* create a new branch off your local bzr.dev copy for each issue
133
(bug or feature) you are working on.
135
This approach makes it easy to go back and make any required changes
136
after a code review. Resubmitting the change is then simple with no
137
risk of accidentially including edits related to other issues you may
138
be working on. After the changes for an issue are accepted and merged,
139
the associated branch can be deleted or archived as you wish.
142
Navigating the Code Base
143
========================
145
.. Was at <http://bazaar-vcs.org/NewDeveloperIntroduction>
147
Some of the key files in this directory are:
150
The command you run to start Bazaar itself. This script is pretty
151
short and just does some checks then jumps into bzrlib.
154
This file covers a brief introduction to Bazaar and lists some of its
158
Summary of changes in each Bazaar release that can affect users or
162
Installs Bazaar system-wide or to your home directory. To perform
163
development work on Bazaar it is not required to run this file - you
164
can simply run the bzr command from the top level directory of your
165
development copy. Note: That if you run setup.py this will create a
166
'build' directory in your development branch. There's nothing wrong
167
with this but don't be confused by it. The build process puts a copy
168
of the main code base into this build directory, along with some other
169
files. You don't need to go in here for anything discussed in this
173
Possibly the most exciting folder of all, bzrlib holds the main code
174
base. This is where you will go to edit python files and contribute to
178
Holds documentation on a whole range of things on Bazaar from the
179
origination of ideas within the project to information on Bazaar
180
features and use cases. Within this directory there is a subdirectory
181
for each translation into a human language. All the documentation
182
is in the ReStructuredText markup language.
185
Documentation specifically targetted at Bazaar and plugin developers.
186
(Including this document.)
190
Automatically-generated API reference information is available at
191
<http://starship.python.net/crew/mwh/bzrlibapi/>.
193
See also the `Bazaar Architectural Overview <../../developers/overview.html>`_.
196
The Code Review Process
197
#######################
199
All code changes coming in to Bazaar are reviewed by someone else.
200
Normally changes by core contributors are reviewed by one other core
201
developer, and changes from other people are reviewed by two core
202
developers. Use intelligent discretion if the patch is trivial.
204
Good reviews do take time. They also regularly require a solid
205
understanding of the overall code base. In practice, this means a small
206
number of people often have a large review burden - with knowledge comes
207
responsibility. No one like their merge requests sitting in a queue going
208
nowhere, so reviewing sooner rather than later is strongly encouraged.
212
Sending patches for review
213
==========================
99
A Closer Look at the Merge & Review Process
100
===========================================
215
102
If you'd like to propose a change, please post to the
216
103
bazaar@lists.canonical.com list with a bundle, patch, or link to a
217
branch. Put ``[PATCH]`` or ``[MERGE]`` in the subject so Bundle Buggy
104
branch. Put '[PATCH]' or '[MERGE]' in the subject so Bundle Buggy
218
105
can pick it out, and explain the change in the email message text.
219
106
Remember to update the NEWS file as part of your change if it makes any
220
107
changes visible to users or plugin developers. Please include a diff
221
108
against mainline if you're giving a link to a branch.
223
You can generate a merge request like this::
110
You can generate a bundle like this::
225
bzr send -o bug-1234.patch
112
bzr bundle > mybundle.patch
227
A ``.patch`` extension is recommended instead of .bundle as many mail clients
228
will send the latter as a binary file.
230
``bzr send`` can also send mail directly if you prefer; see the help.
114
A .patch extension is recommended instead of .bundle as many mail clients
115
will send the latter as a binary file. If a bundle would be too long or your
116
mailer mangles whitespace (e.g. implicitly converts Unix newlines to DOS
117
newlines), use the merge-directive command instead like this::
119
bzr merge-directive http://bazaar-vcs.org http://example.org/my_branch > my_directive.patch
121
See the help for details on the arguments to merge-directive.
232
123
Please do **NOT** put [PATCH] or [MERGE] in the subject line if you don't
233
124
want it to be merged. If you want comments from developers rather than
234
to be merged, you can put ``[RFC]`` in the subject line.
236
If this change addresses a bug, please put the bug number in the subject
237
line too, in the form ``[#1]`` so that Bundle Buggy can recognize it.
239
If the change is intended for a particular release mark that in the
240
subject too, e.g. ``[1.6]``.
246
Please put a "cover letter" on your merge request explaining:
248
* the reason **why** you're making this change
250
* **how** this change achieves this purpose
252
* anything else you may have fixed in passing
254
* anything significant that you thought of doing, such as a more
255
extensive fix or a different approach, but didn't or couldn't do now
257
A good cover letter makes reviewers' lives easier because they can decide
258
from the letter whether they agree with the purpose and approach, and then
259
assess whether the patch actually does what the cover letter says.
260
Explaining any "drive-by fixes" or roads not taken may also avoid queries
261
from the reviewer. All in all this should give faster and better reviews.
262
Sometimes writing the cover letter helps the submitter realize something
263
else they need to do. The size of the cover letter should be proportional
264
to the size and complexity of the patch.
267
Reviewing proposed changes
268
==========================
270
Anyone is welcome to review code, and reply to the thread with their
273
The simplest way to review a proposed change is to just read the patch on
274
the list or in Bundle Buggy. For more complex changes it may be useful
275
to make a new working tree or branch from trunk, and merge the proposed
276
change into it, so you can experiment with the code or look at a wider
279
There are three main requirements for code to get in:
281
* Doesn't reduce test coverage: if it adds new methods or commands,
282
there should be tests for them. There is a good test framework
283
and plenty of examples to crib from, but if you are having trouble
284
working out how to test something feel free to post a draft patch
287
* Doesn't reduce design clarity, such as by entangling objects
288
we're trying to separate. This is mostly something the more
289
experienced reviewers need to help check.
291
* Improves bugs, features, speed, or code simplicity.
293
Code that goes in should not degrade any of these aspects. Patches are
294
welcome that only cleanup the code without changing the external
295
behaviour. The core developers take care to keep the code quality high
296
and understandable while recognising that perfect is sometimes the enemy
299
It is easy for reviews to make people notice other things which should be
300
fixed but those things should not hold up the original fix being accepted.
301
New things can easily be recorded in the Bug Tracker instead.
303
It's normally much easier to review several smaller patches than one large
304
one. You might want to use ``bzr-loom`` to maintain threads of related
305
work, or submit a preparatory patch that will make your "real" change
309
Checklist for reviewers
310
=======================
312
* Do you understand what the code's doing and why?
314
* Will it perform reasonably for large inputs, both in memory size and
315
run time? Are there some scenarios where performance should be
318
* Is it tested, and are the tests at the right level? Are there both
319
blackbox (command-line level) and API-oriented tests?
321
* If this change will be visible to end users or API users, is it
322
appropriately documented in NEWS?
324
* Does it meet the coding standards below?
326
* If it changes the user-visible behaviour, does it update the help
327
strings and user documentation?
329
* If it adds a new major concept or standard practice, does it update the
330
developer documentation?
332
* (your ideas here...)
335
Bundle Buggy and review outcomes
336
================================
338
Anyone can "vote" on the mailing list by expressing an opinion. Core
339
developers can also vote using Bundle Buggy. Here are the voting codes and
125
to be merged, you can put '[RFC]' in the subject line.
127
Anyone is welcome to review code. There are broadly three gates for
130
* Doesn't reduce test coverage: if it adds new methods or commands,
131
there should be tests for them. There is a good test framework
132
and plenty of examples to crib from, but if you are having trouble
133
working out how to test something feel free to post a draft patch
136
* Doesn't reduce design clarity, such as by entangling objects
137
we're trying to separate. This is mostly something the more
138
experienced reviewers need to help check.
140
* Improves bugs, features, speed, or code simplicity.
142
Code that goes in should pass all three. The core developers take care
143
to keep the code quality high and understandable while recognising that
144
perfect is sometimes the enemy of good. (It is easy for reviews to make
145
people notice other things which should be fixed but those things should
146
not hold up the original fix being accepted. New things can easily be
147
recorded in the Bug Tracker instead.)
149
Anyone can "vote" on the mailing list. Core developers can also vote using
150
Bundle Buggy. Here are the voting codes and their explanations.
342
152
:approve: Reviewer wants this submission merged.
343
153
:tweak: Reviewer wants this submission merged with small changes. (No
360
170
outstanding merge requests together with an explanation of the columns.
361
171
Bundle Buggy will also mail you a link to track just your change.
174
Preparing a Sandbox for Making Changes to Bazaar
175
================================================
177
Bazaar supports many ways of organising your work. See
178
http://bazaar-vcs.org/SharedRepositoryLayouts for a summary of the
179
popular alternatives.
181
Of course, the best choice for you will depend on numerous factors:
182
the number of changes you may be making, the complexity of the changes, etc.
183
As a starting suggestion though:
185
* create a local copy of the main development branch (bzr.dev) by using
188
bzr branch http://bazaar-vcs.org/bzr/bzr.dev/ bzr.dev
190
* keep your copy of bzr.dev prestine (by not developing in it) and keep
191
it up to date (by using bzr pull)
193
* create a new branch off your local bzr.dev copy for each issue
194
(bug or feature) you are working on.
196
This approach makes it easy to go back and make any required changes
197
after a code review. Resubmitting the change is then simple with no
198
risk of accidentially including edits related to other issues you may
199
be working on. After the changes for an issue are accepted and merged,
200
the associated branch can be deleted or archived as you wish.
203
Navigating the Code Base
204
========================
206
TODO: List and describe in one line the purpose of each directory
207
inside an installation of bzr.
209
TODO: Refer to a central location holding an up to date copy of the API
210
documentation generated by epydoc, e.g. something like
211
http://starship.python.net/crew/mwh/bzrlibapi/bzrlib.html.
217
The Importance of Testing
218
=========================
220
Reliability is a critical success factor for any Version Control System.
221
We want Bazaar to be highly reliable across multiple platforms while
222
evolving over time to meet the needs of its community.
224
In a nutshell, this is want we expect and encourage:
226
* New functionality should have test cases. Preferably write the
227
test before writing the code.
229
In general, you can test at either the command-line level or the
230
internal API level. See Writing tests below for more detail.
232
* Try to practice Test-Driven Development: before fixing a bug, write a
233
test case so that it does not regress. Similarly for adding a new
234
feature: write a test case for a small version of the new feature before
235
starting on the code itself. Check the test fails on the old code, then
236
add the feature or fix and check it passes.
238
By doing these things, the Bazaar team gets increased confidence that
239
changes do what they claim to do, whether provided by the core team or
240
by community members. Equally importantly, we can be surer that changes
241
down the track do not break new features or bug fixes that you are
244
As of May 2007, Bazaar ships with a test suite containing over 6000 tests
245
and growing. We are proud of it and want to remain so. As community
246
members, we all benefit from it. Would you trust version control on
247
your project to a product *without* a test suite like Bazaar has?
250
Running the Test Suite
251
======================
253
Currently, bzr selftest is used to invoke tests.
254
You can provide a pattern argument to run a subset. For example,
255
to run just the blackbox tests, run::
257
./bzr selftest -v blackbox
259
To skip a particular test (or set of tests), use the --exclude option
260
(shorthand -x) like so::
262
./bzr selftest -v -x blackbox
264
To ensure that all tests are being run and succeeding, you can use the
265
--strict option which will fail if there are any missing features or known
268
./bzr selftest --strict
270
To list tests without running them, use the --list-only option like so::
272
./bzr selftest --list-only
274
This option can be combined with other selftest options (like -x) and
275
filter patterns to understand their effect.
281
In general tests should be placed in a file named test_FOO.py where
282
FOO is the logical thing under test. That file should be placed in the
283
tests subdirectory under the package being tested.
285
For example, tests for merge3 in bzrlib belong in bzrlib/tests/test_merge3.py.
286
See bzrlib/tests/test_sampler.py for a template test script.
288
Tests can be written for the UI or for individual areas of the library.
289
Choose whichever is appropriate: if adding a new command, or a new command
290
option, then you should be writing a UI test. If you are both adding UI
291
functionality and library functionality, you will want to write tests for
292
both the UI and the core behaviours. We call UI tests 'blackbox' tests
293
and they are found in ``bzrlib/tests/blackbox/*.py``.
295
When writing blackbox tests please honour the following conventions:
297
1. Place the tests for the command 'name' in
298
bzrlib/tests/blackbox/test_name.py. This makes it easy for developers
299
to locate the test script for a faulty command.
301
2. Use the 'self.run_bzr("name")' utility function to invoke the command
302
rather than running bzr in a subprocess or invoking the
303
cmd_object.run() method directly. This is a lot faster than
304
subprocesses and generates the same logging output as running it in a
305
subprocess (which invoking the method directly does not).
307
3. Only test the one command in a single test script. Use the bzrlib
308
library when setting up tests and when evaluating the side-effects of
309
the command. We do this so that the library api has continual pressure
310
on it to be as functional as the command line in a simple manner, and
311
to isolate knock-on effects throughout the blackbox test suite when a
312
command changes its name or signature. Ideally only the tests for a
313
given command are affected when a given command is changed.
315
4. If you have a test which does actually require running bzr in a
316
subprocess you can use ``run_bzr_subprocess``. By default the spawned
317
process will not load plugins unless ``--allow-plugins`` is supplied.
323
We make selective use of doctests__. In general they should provide
324
*examples* within the API documentation which can incidentally be tested. We
325
don't try to test every important case using doctests -- regular Python
326
tests are generally a better solution.
328
Most of these are in ``bzrlib/doc/api``. More additions are welcome.
330
__ http://docs.python.org/lib/module-doctest.html
333
Skipping tests and test requirements
334
------------------------------------
336
In our enhancements to unittest we allow for some addition results beyond
337
just success or failure.
339
If a test can't be run, it can say that it's skipped. This is typically
340
used in parameterized tests - for example if a transport doesn't support
341
setting permissions, we'll skip the tests that relating to that. ::
344
return self.branch_format.initialize(repo.bzrdir)
345
except errors.UninitializableFormat:
346
raise tests.TestSkipped('Uninitializable branch format')
348
Raising TestSkipped is a good idea when you want to make it clear that the
349
test was not run, rather than just returning which makes it look as if it
352
Several different cases are distinguished:
355
Generic skip; the only type that was present up to bzr 0.18.
358
The test doesn't apply to the parameters with which it was run.
359
This is typically used when the test is being applied to all
360
implementations of an interface, but some aspects of the interface
361
are optional and not present in particular concrete
362
implementations. (Some tests that should raise this currently
363
either silently return or raise TestSkipped.) Another option is
364
to use more precise parameterization to avoid generating the test
368
**(Not implemented yet)**
369
The test can't be run because of an inherent limitation of the
370
environment, such as not having symlinks or not supporting
374
The test can't be run because a dependency (typically a Python
375
library) is not available in the test environment. These
376
are in general things that the person running the test could fix
377
by installing the library. It's OK if some of these occur when
378
an end user runs the tests or if we're specifically testing in a
379
limited environment, but a full test should never see them.
382
The test exists but is known to fail, for example because the
383
code to fix it hasn't been run yet. Raising this allows
384
you to distinguish these failures from the ones that are not
385
expected to fail. This could be conditionally raised if something
386
is broken on some platforms but not on others.
388
We plan to support three modes for running the test suite to control the
389
interpretation of these results. Strict mode is for use in situations
390
like merges to the mainline and releases where we want to make sure that
391
everything that can be tested has been tested. Lax mode is for use by
392
developers who want to temporarily tolerate some known failures. The
393
default behaviour is obtained by ``bzr selftest`` with no options, and
394
also (if possible) by running under another unittest harness.
396
======================= ======= ======= ========
397
result strict default lax
398
======================= ======= ======= ========
399
TestSkipped pass pass pass
400
TestNotApplicable pass pass pass
401
TestPlatformLimit pass pass pass
402
TestDependencyMissing fail pass pass
403
KnownFailure fail pass pass
404
======================= ======= ======= ========
407
Test feature dependencies
408
-------------------------
410
Rather than manually checking the environment in each test, a test class
411
can declare its dependence on some test features. The feature objects are
412
checked only once for each run of the whole test suite.
414
For historical reasons, as of May 2007 many cases that should depend on
415
features currently raise TestSkipped.)
419
class TestStrace(TestCaseWithTransport):
421
_test_needs_features = [StraceFeature]
423
This means all tests in this class need the feature. The feature itself
424
should provide a ``_probe`` method which is called once to determine if
427
These should generally be equivalent to either TestDependencyMissing or
428
sometimes TestPlatformLimit.
434
Known failures are when a test exists but we know it currently doesn't
435
work, allowing the test suite to still pass. These should be used with
436
care, we don't want a proliferation of quietly broken tests. It might be
437
appropriate to use them if you've committed a test for a bug but not the
438
fix for it, or if something works on Unix but not on Windows.
441
Testing exceptions and errors
442
-----------------------------
444
It's important to test handling of errors and exceptions. Because this
445
code is often not hit in ad-hoc testing it can often have hidden bugs --
446
it's particularly common to get NameError because the exception code
447
references a variable that has since been renamed.
449
.. TODO: Something about how to provoke errors in the right way?
451
In general we want to test errors at two levels:
453
1. A test in ``test_errors.py`` checking that when the exception object is
454
constructed with known parameters it produces an expected string form.
455
This guards against mistakes in writing the format string, or in the
456
``str`` representations of its parameters. There should be one for
457
each exception class.
459
2. Tests that when an api is called in a particular situation, it raises
460
an error of the expected class. You should typically use
461
``assertRaises``, which in the Bazaar test suite returns the exception
462
object to allow you to examine its parameters.
464
In some cases blackbox tests will also want to check error reporting. But
465
it can be difficult to provoke every error through the commandline
466
interface, so those tests are only done as needed -- eg in response to a
467
particular bug or if the error is reported in an unusual way(?) Blackbox
468
tests should mostly be testing how the command-line interface works, so
469
should only test errors if there is something particular to the cli in how
470
they're displayed or handled.
476
The Python ``warnings`` module is used to indicate a non-fatal code
477
problem. Code that's expected to raise a warning can be tested through
480
The test suite can be run with ``-Werror`` to check no unexpected errors
483
However, warnings should be used with discretion. It's not an appropriate
484
way to give messages to the user, because the warning is normally shown
485
only once per source line that causes the problem. You should also think
486
about whether the warning is serious enought that it should be visible to
487
users who may not be able to fix it.
490
Interface implementation testing and test scenarios
491
---------------------------------------------------
493
There are several cases in Bazaar of multiple implementations of a common
494
conceptual interface. ("Conceptual" because
495
it's not necessary for all the implementations to share a base class,
496
though they often do.) Examples include transports and the working tree,
497
branch and repository classes.
499
In these cases we want to make sure that every implementation correctly
500
fulfils the interface requirements. For example, every Transport should
501
support the ``has()`` and ``get()`` and ``clone()`` methods. We have a
502
sub-suite of tests in ``test_transport_implementations``. (Most
503
per-implementation tests are in submodules of ``bzrlib.tests``, but not
504
the transport tests at the moment.)
506
These tests are repeated for each registered Transport, by generating a
507
new TestCase instance for the cross product of test methods and transport
508
implementations. As each test runs, it has ``transport_class`` and
509
``transport_server`` set to the class it should test. Most tests don't
510
access these directly, but rather use ``self.get_transport`` which returns
511
a transport of the appropriate type.
513
The goal is to run per-implementation only tests that relate to that
514
particular interface. Sometimes we discover a bug elsewhere that happens
515
with only one particular transport. Once it's isolated, we can consider
516
whether a test should be added for that particular implementation,
517
or for all implementations of the interface.
519
The multiplication of tests for different implementations is normally
520
accomplished by overriding the ``test_suite`` function used to load
521
tests from a module. This function typically loads all the tests,
522
then applies a TestProviderAdapter to them, which generates a longer
523
suite containing all the test variations.
529
Some utilities are provided for generating variations of tests. This can
530
be used for per-implementation tests, or other cases where the same test
531
code needs to run several times on different scenarios.
533
The general approach is to define a class that provides test methods,
534
which depend on attributes of the test object being pre-set with the
535
values to which the test should be applied. The test suite should then
536
also provide a list of scenarios in which to run the tests.
538
Typically ``multiply_tests_from_modules`` should be called from the test
539
module's ``test_suite`` function.
542
Essential Domain Classes
543
########################
545
Introducing the Object Model
546
============================
548
The core domain objects within the bazaar model are:
558
Transports are explained below. See http://bazaar-vcs.org/Classes/
559
for an introduction to the other key classes.
564
The ``Transport`` layer handles access to local or remote directories.
565
Each Transport object acts like a logical connection to a particular
566
directory, and it allows various operations on files within it. You can
567
*clone* a transport to get a new Transport connected to a subdirectory or
570
Transports are not used for access to the working tree. At present
571
working trees are always local and they are accessed through the regular
572
Python file io mechanisms.
577
Transports work in URLs. Take note that URLs are by definition only
578
ASCII - the decision of how to encode a Unicode string into a URL must be
579
taken at a higher level, typically in the Store. (Note that Stores also
580
escape filenames which cannot be safely stored on all filesystems, but
581
this is a different level.)
583
The main reason for this is that it's not possible to safely roundtrip a
584
URL into Unicode and then back into the same URL. The URL standard
585
gives a way to represent non-ASCII bytes in ASCII (as %-escapes), but
586
doesn't say how those bytes represent non-ASCII characters. (They're not
587
guaranteed to be UTF-8 -- that is common but doesn't happen everywhere.)
589
For example if the user enters the url ``http://example/%e0`` there's no
590
way to tell whether that character represents "latin small letter a with
591
grave" in iso-8859-1, or "latin small letter r with acute" in iso-8859-2
592
or malformed UTF-8. So we can't convert their URL to Unicode reliably.
594
Equally problematic if we're given a url-like string containing non-ascii
595
characters (such as the accented a) we can't be sure how to convert that
596
to the correct URL, because we don't know what encoding the server expects
597
for those characters. (Although this is not totally reliable we might still
598
accept these and assume they should be put into UTF-8.)
600
A similar edge case is that the url ``http://foo/sweet%2Fsour`` contains
601
one directory component whose name is "sweet/sour". The escaped slash is
602
not a directory separator. If we try to convert URLs to regular Unicode
603
paths this information will be lost.
605
This implies that Transports must natively deal with URLs; for simplicity
606
they *only* deal with URLs and conversion of other strings to URLs is done
607
elsewhere. Information they return, such as from ``list_dir``, is also in
608
the form of URL components.
617
We have a commitment to 6 months API stability - any supported symbol in a
618
release of bzr MUST NOT be altered in any way that would result in
619
breaking existing code that uses it. That means that method names,
620
parameter ordering, parameter names, variable and attribute names etc must
621
not be changed without leaving a 'deprecated forwarder' behind. This even
622
applies to modules and classes.
624
If you wish to change the behaviour of a supported API in an incompatible
625
way, you need to change its name as well. For instance, if I add an optional keyword
626
parameter to branch.commit - that's fine. On the other hand, if I add a
627
keyword parameter to branch.commit which is a *required* transaction
628
object, I should rename the API - i.e. to 'branch.commit_transaction'.
630
When renaming such supported API's, be sure to leave a deprecated_method (or
631
_function or ...) behind which forwards to the new API. See the
632
bzrlib.symbol_versioning module for decorators that take care of the
633
details for you - such as updating the docstring, and issuing a warning
634
when the old api is used.
636
For unsupported API's, it does not hurt to follow this discipline, but it's
637
not required. Minimally though, please try to rename things so that
638
callers will at least get an AttributeError rather than weird results.
641
Deprecation decorators
642
----------------------
644
``bzrlib.symbol_versioning`` provides decorators that can be attached to
645
methods, functions, and other interfaces to indicate that they should no
648
To deprecate a static method you must call ``deprecated_function``
649
(**not** method), after the staticmethod call::
652
@deprecated_function(zero_ninetyone)
653
def create_repository(base, shared=False, format=None):
655
When you deprecate an API, you should not just delete its tests, because
656
then we might introduce bugs in them. If the API is still present at all,
657
it should still work. The basic approach is to use
658
``TestCase.applyDeprecated`` which in one step checks that the API gives
659
the expected deprecation message, and also returns the real result from
660
the method, so that tests can keep running.
363
662
Coding Style Guidelines
364
#######################
663
=======================
369
668
``hasattr`` should not be used because it swallows exceptions including
370
669
``KeyboardInterrupt``. Instead, say something like ::
648
923
being phased out.
651
Object string representations
652
=============================
654
Python prints objects using their ``__repr__`` method when they are
655
written to logs, exception tracebacks, or the debugger. We want
656
objects to have useful representations to help in determining what went
659
If you add a new class you should generally add a ``__repr__`` method
660
unless there is an adequate method in a parent class. There should be a
663
Representations should typically look like Python constructor syntax, but
664
they don't need to include every value in the object and they don't need
665
to be able to actually execute. They're to be read by humans, not
666
machines. Don't hardcode the classname in the format, so that we get the
667
correct value if the method is inherited by a subclass. If you're
668
printing attributes of the object, including strings, you should normally
669
use ``%r`` syntax (to call their repr in turn).
671
Try to avoid the representation becoming more than one or two lines long.
672
(But balance this against including useful information, and simplicity of
675
Because repr methods are often called when something has already gone
676
wrong, they should be written somewhat more defensively than most code.
677
The object may be half-initialized or in some other way in an illegal
678
state. The repr method shouldn't raise an exception, or it may hide the
679
(probably more useful) underlying exception.
684
return '%s(%r)' % (self.__class__.__name__,
691
A bare ``except`` statement will catch all exceptions, including ones that
692
really should terminate the program such as ``MemoryError`` and
693
``KeyboardInterrupt``. They should rarely be used unless the exception is
694
later re-raised. Even then, think about whether catching just
695
``Exception`` (which excludes system errors in Python2.5 and later) would
702
All code should be exercised by the test suite. See `Guide to Testing
703
Bazaar <../../developers/testing.html>`_ for detailed information about writing tests.
712
We have a commitment to 6 months API stability - any supported symbol in a
713
release of bzr MUST NOT be altered in any way that would result in
714
breaking existing code that uses it. That means that method names,
715
parameter ordering, parameter names, variable and attribute names etc must
716
not be changed without leaving a 'deprecated forwarder' behind. This even
717
applies to modules and classes.
719
If you wish to change the behaviour of a supported API in an incompatible
720
way, you need to change its name as well. For instance, if I add an optional keyword
721
parameter to branch.commit - that's fine. On the other hand, if I add a
722
keyword parameter to branch.commit which is a *required* transaction
723
object, I should rename the API - i.e. to 'branch.commit_transaction'.
725
When renaming such supported API's, be sure to leave a deprecated_method (or
726
_function or ...) behind which forwards to the new API. See the
727
bzrlib.symbol_versioning module for decorators that take care of the
728
details for you - such as updating the docstring, and issuing a warning
729
when the old api is used.
731
For unsupported API's, it does not hurt to follow this discipline, but it's
732
not required. Minimally though, please try to rename things so that
733
callers will at least get an AttributeError rather than weird results.
736
Deprecation decorators
737
----------------------
739
``bzrlib.symbol_versioning`` provides decorators that can be attached to
740
methods, functions, and other interfaces to indicate that they should no
741
longer be used. For example::
743
@deprecated_method(deprecated_in((0, 1, 4)))
745
return self._new_foo()
747
To deprecate a static method you must call ``deprecated_function``
748
(**not** method), after the staticmethod call::
751
@deprecated_function(deprecated_in((0, 1, 4)))
752
def create_repository(base, shared=False, format=None):
754
When you deprecate an API, you should not just delete its tests, because
755
then we might introduce bugs in them. If the API is still present at all,
756
it should still work. The basic approach is to use
757
``TestCase.applyDeprecated`` which in one step checks that the API gives
758
the expected deprecation message, and also returns the real result from
759
the method, so that tests can keep running.
761
Deprecation warnings will be suppressed for final releases, but not for
762
development versions or release candidates, or when running ``bzr
763
selftest``. This gives developers information about whether their code is
764
using deprecated functions, but avoids confusing users about things they
1007
In general tests should be placed in a file named test_FOO.py where
1008
FOO is the logical thing under test. That file should be placed in the
1009
tests subdirectory under the package being tested.
1011
For example, tests for merge3 in bzrlib belong in bzrlib/tests/test_merge3.py.
1012
See bzrlib/tests/test_sampler.py for a template test script.
1014
Tests can be written for the UI or for individual areas of the library.
1015
Choose whichever is appropriate: if adding a new command, or a new command
1016
option, then you should be writing a UI test. If you are both adding UI
1017
functionality and library functionality, you will want to write tests for
1018
both the UI and the core behaviours. We call UI tests 'blackbox' tests
1019
and they are found in ``bzrlib/tests/blackbox/*.py``.
1021
When writing blackbox tests please honour the following conventions:
1023
1. Place the tests for the command 'name' in
1024
bzrlib/tests/blackbox/test_name.py. This makes it easy for developers
1025
to locate the test script for a faulty command.
1027
2. Use the 'self.run_bzr("name")' utility function to invoke the command
1028
rather than running bzr in a subprocess or invoking the
1029
cmd_object.run() method directly. This is a lot faster than
1030
subprocesses and generates the same logging output as running it in a
1031
subprocess (which invoking the method directly does not).
1033
3. Only test the one command in a single test script. Use the bzrlib
1034
library when setting up tests and when evaluating the side-effects of
1035
the command. We do this so that the library api has continual pressure
1036
on it to be as functional as the command line in a simple manner, and
1037
to isolate knock-on effects throughout the blackbox test suite when a
1038
command changes its name or signature. Ideally only the tests for a
1039
given command are affected when a given command is changed.
1041
4. If you have a test which does actually require running bzr in a
1042
subprocess you can use ``run_bzr_subprocess``. By default the spawned
1043
process will not load plugins unless ``--allow-plugins`` is supplied.
1049
We have a rich collection of tools to support writing tests. Please use
1050
them in preference to ad-hoc solutions as they provide portability and
1051
performance benefits.
1056
The ``TreeBuilder`` interface allows the construction of arbitrary trees
1057
with a declarative interface. A sample session might look like::
1059
tree = self.make_branch_and_tree('path')
1060
builder = TreeBuilder()
1061
builder.start_tree(tree)
1062
builder.build(['foo', "bar/", "bar/file"])
1063
tree.commit('commit the tree')
1064
builder.finish_tree()
1066
Please see bzrlib.treebuilder for more details.
1071
The ``BranchBuilder`` interface allows the creation of test branches in a
1072
quick and easy manner. A sample session::
1074
builder = BranchBuilder(self.get_transport().clone('relpath'))
1075
builder.build_commit()
1076
builder.build_commit()
1077
builder.build_commit()
1078
branch = builder.get_branch()
1080
Please see bzrlib.branchbuilder for more details.
1085
We make selective use of doctests__. In general they should provide
1086
*examples* within the API documentation which can incidentally be tested. We
1087
don't try to test every important case using doctests -- regular Python
1088
tests are generally a better solution.
1090
Most of these are in ``bzrlib/doc/api``. More additions are welcome.
1092
__ http://docs.python.org/lib/module-doctest.html
1097
Currently, bzr selftest is used to invoke tests.
1098
You can provide a pattern argument to run a subset. For example,
1099
to run just the blackbox tests, run::
1101
./bzr selftest -v blackbox
1103
To skip a particular test (or set of tests), use the --exclude option
1104
(shorthand -x) like so::
1106
./bzr selftest -v -x blackbox
1108
To list tests without running them, use the --list-only option like so::
1110
./bzr selftest --list-only
1112
This option can be combined with other selftest options (like -x) and
1113
filter patterns to understand their effect.
879
1116
Handling Errors and Exceptions
880
1117
==============================
1523
1747
As well as prioritizing bugs and nominating them against a
1524
1748
target milestone, Launchpad lets core developers offer to mentor others in
1758
To start a new release cycle:
1760
#. Send mail to the list with the key dates, who will be the release
1761
manager, and the main themes or targetted bugs. Ask people to nominate
1762
objectives, or point out an high-risk things that are best done early,
1763
or that interact with other changes.
1765
#. Add a new "series" in Launchpad at <https://launchpad.net/bzr/+addseries>. There is one
1766
series for every *x.y* release.
1768
Weekly Status Updates
1769
---------------------
1771
TODO: Things to cover:
1773
* Early communication to downstream teams (e.g. Launchpad) about changes in dependencies.
1774
* Reminder re lifecycle and where we're up to right now
1775
* Summary of recent successes and pending work
1776
* Reminder re release objectives
1777
* Reminder re things needing attention, e.g. bug triage, reviews, testing of certain things, etc.
1783
TODO: Get material from http://bazaar-vcs.org/FeatureFreeze.
1787
Making a Release or Release Candidate
1788
-------------------------------------
1790
.. Was previously at http://bazaar-vcs.org/ReleaseChecklist
1792
.. TODO: Still needs more clarity on what's in a RC versus a final
1795
.. TODO: Too much of this is manual but could be automated...
1797
This is the procedure for making a new bzr release:
1799
#. If the release is the first candidate, make a new branch in PQM. (Contact RobertCollins for this step).
1801
Register the branch at https://launchpad.net/products/bzr/+addbranch
1803
#. Run the automatic test suite and any non-automated tests. (For example, try a download over http; these should eventually be scripted though not automatically run.). Try to have all optional dependencies installed so that there are no tests skipped. Also make sure that you have the c extensions compiled (``make`` or ``python setup.py build_ext -i``).
1805
#. In the release branch, update ``version_info`` in ``./bzrlib/__init__.py``
1807
#. Add the date and release number to ``./NEWS``.
1809
#. Update the release number in the README. (It's not there as of 0.15, but please check).
1811
#. Commit these changes to the release branch, using a command like::
1813
bzr commit -m "(jam) Release 0.12rc1."
1815
The diff before you commit will be something like::
1817
=== modified file 'NEWS'
1818
--- NEWS 2006-10-23 13:11:17 +0000
1819
+++ NEWS 2006-10-23 22:50:50 +0000
1822
+bzr 0.12rc1 2006-10-23
1827
=== modified file 'bzrlib/__init__.py'
1828
--- bzrlib/__init__.py 2006-10-16 01:47:43 +0000
1829
+++ bzrlib/__init__.py 2006-10-23 22:49:46 +0000
1831
# Python version 2.0 is (2, 0, 0, 'final', 0)." Additionally we use a
1832
# releaselevel of 'dev' for unreleased under-development code.
1834
-version_info = (0, 12, 0, 'dev', 0)
1835
+version_info = (0, 12, 0, 'candidate', 1)
1837
if version_info[3] == 'final':
1838
version_string = '%d.%d.%d' % version_info[:3]
1840
#. Send the changes to PQM, to update the official master branch.
1842
#. When PQM succeeds, pull down the master release branch.
1844
#. Merge the release branch back into the trunk. Check that changes in NEWS were merged into the right sections. If it's not already done, advance the version number in bzr and bzrlib/__init__.py Submit this back into pqm for bzr.dev.
1846
#. Make a distribution directory by running e.g. ``bzr export /tmp/bzr-<version>/`` in the working directory.
1848
#. Run make in /tmp/bzr-<version>. This creates the extensions from the pyrex source.
1850
#. Run the test suite in the distribution directory
1852
#. Run ``setup.py install`` --root=prefix to do a test install into your system directory, home directory, or some other prefix. Check the install worked and that the installed version is usable. (run the bzr script from the installed path with PYTHONPATH set to the site-packages directory it created). i.e. ::
1854
python setup.py install --root=installed
1855
PYTHONPATH=installed/usr/lib/python2.4/site-packages installed/usr/bin/bzr
1857
#. Clean the tree to get rid of .pyc files etc: make clean && rm -rf build && rm bzrlib/_*.c bzrlib/_*.so
1859
#. Generate the reference documentation in text format: make doc/en/user-reference/bzr_man.txt.
1861
#. Change back to your original branch and then run: make clean && make to create the compiled pyrex extensions. You then need to copy the .c files over to the exported directory.
1863
``find . -name "*.c"`` will tell you which files you need.
1865
#. Create the release tarball::
1867
cd /tmp && tar czf bzr-<version>.tar.gz bzr-<version>
1869
#. Sign the tarball with e.g. ``gpg --detach-sign -a bzr-0.10rc1.tar.gz``
1872
Publishing the release
1873
----------------------
1875
Now you have the releasable product. The next step is making it
1876
available to the world.
1878
#. In <https://launchpad.net/bzr/> click the "Release series" for this
1879
series, to take you to e.g. <https://launchpad.net/bzr/1.1>. Then
1880
click "Register a release", and add information about this release.
1882
#. Within that release, upload the source tarball and the GPG signature.
1884
(These used to also be uploaded to
1885
<sftp://escudero.ubuntu.com/srv/bazaar.canonical.com/www/releases/src>
1886
but that's not accessible to all developers, and gets some mime types
1889
#. Link from http://bazaar-vcs.org/Download to the tarball and signature.
1891
#. Update http://doc.bazaar-vcs.org/ to have a directory of documentation
1892
for this release. (Controlled by the ``update-bzr-docs`` script on
1893
escudero, and also update the ``latest`` symlink in
1894
``/srv/bazaar.canonical.com/doc/``.)
1896
#. Announce on the `Bazaar home page`__
1898
__ http://bazaar-vcs.org/
1901
Announcing the release
1902
----------------------
1904
Now that the release is publicly available, tell people about it.
1906
#. Announce to ``bazaar-announce`` and ``bazaar`` mailing lists.
1907
The announce mail will look something like this:
1909
| Subject: bzr 0.11 release candidate 1
1911
| INTRO HERE. Mention the release number and date, and why the release. (i.e. release candidate for testing, final release of a version, backport/bugfix etc).
1914
| http://bazaar-vcs.org/releases/src/bzr-VERSION.tar.gz
1915
| and GPG signature:
1916
| http://bazaar-vcs.org/releases/src/bzr-VERSION.tar.gz.sig
1918
| DESCRIBE-CHANGES-IN-OVERVIEW-HERE
1920
| DESCRIBE-when the next release will be (if there is another - i.e. this is a release candidate)
1922
| Many thanks to all the contributors to this release! I've included the
1923
| contents of NEWS for VERSION below:
1925
To generate the data from NEWS, just copy and paste the relevant news section and clean it up as appropriate. The main clean-up task is to confirm that all major changes are indeed covered. This can be done by running ``bzr log`` back to the point when the branch was opened and cross checking the changes against the NEWS entries.
1927
(RC announcements should remind plugin maintainers to update their plugins.)
1929
* For point releases (i.e. a release candidate, or an incremental fix to a released version) take everything in the relevant NEWS secion : for 0.11rc2 take everything in NEWS from the bzr 0.11rc2 line to the bzr 0.11rc1 line further down.
1931
* For major releases (i.e. 0.11, 0.12 etc), take all the combined NEWS sections from within that version: for 0.11 take all of the 0.11 specific section, plus 0.11rc2, plus 0.11rc1 etc.
1933
#. Update the `news side menu`__ -- this currently requires downloading the file, editing it, deleting it, and uploading a replacement.
1935
__ http://bazaar-vcs.org/site/menu?action=AttachFile&do=view&target=news.html
1937
#. Update the IRC channel topic. Use the ``/topic`` command to do this, ensuring the new topic text keeps the project name, web site link, etc.
1939
#. Announce on http://freshmeat.net/projects/bzr/
1941
This should be done for both release candidates and final releases. If you do not have a Freshmeat account yet, ask one of the existing admins.
1943
#. Update http://en.wikipedia.org/wiki/Bzr -- this should be done for final releases but not Release Candidates.
1945
#. Package maintainers should update packages when they see the
1950
#. Post to http://mail.python.org/mailman/listinfo/python-announce-list for major releases
1952
#. Update the python package index: <http://pypi.python.org/pypi/bzr> - best
1955
python setup.py register
1957
Remember to check the results afterwards.
1960
Making Win32 installers
1961
-----------------------
1963
**XXX:** This information is now probably obsolete, as Alexander uploads
1964
direct to Launchpad. --mbp 20080116
1966
Alexander Belchenko has been very good about getting packaged installers compiled (see Win32ReleaseChecklist for details). He generally e-mails John Arbash Meinel when they are ready. This is just a brief checklist of what needs to be done.
1968
#. Download and verify the sha1 sums and gpg signatures. Frequently the sha1 files are in dos mode, and need to be converted to unix mode (strip off the trailing ``\r``) before they veryify correctly.
1970
#. Upload to the Launchpad page for this release.
1972
#. Upload to escudero (to the b.c.c/www/releases/win32 directory) using sftp, lftp or rsync
1974
#. Cat the contents of the .sha1 files into the SHA1SUM.
1976
#. Update the SHA1SUM and MD5SUM files using something like ``md5sum bzr-0.14.0.win32.exe >> MD5SUM``. Make sure you use append (>>) rather than overwrite (>).
1978
#. Verify once again that everything is correct with ``sha1sum -c SHA1SUM`` and ``md5sum -c MD5SUM``.
1980
#. Update ``.htaccess`` so that the 'bzr-latest.win32.exe' links point to the latest release. This is not done for candidate releases, only for final releases. (example: bzr-0.14.0, but not bzr-0.14.0rc1).
1982
#. Make sure these urls work as expected:
1984
http://bazaar-vcs.org/releases/win32/bzr-latest.win32-py2.5.exe
1986
http://bazaar-vcs.org/releases/win32/bzr-latest.win32-py2.5.exe.asc
1988
http://bazaar-vcs.org/releases/win32/bzr-latest.win32-py2.4.exe
1990
http://bazaar-vcs.org/releases/win32/bzr-latest.win32-py2.4.exe.asc
1992
http://bazaar-vcs.org/releases/win32/bzr-setup-latest.exe
1994
http://bazaar-vcs.org/releases/win32/bzr-setup-latest.exe.asc
1996
They should all try to download a file with the correct version number.
1998
#. Update http://bazaar-vcs.org/Download to indicate the newly available versions.
2000
#. Update http://bazaar-vcs.org/WindowsDownloads to have the correct version number as well as the correct sha1sum displayed.
added
removed
doc/developers/HACKING.txt
