14
14
test before writing the code.
16
16
In general, you can test at either the command-line level or the
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internal API level. See Writing Tests below for more detail.
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internal API level. Choose whichever is appropriate: if adding a
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new command, or a new command option, then call through run_bzr().
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It is not necessary to do both. Tests that test the command line level
20
are appropriate for checking the UI behaves well - bug fixes and
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core improvements should be tested closer to the code that is doing the
22
work. Command line level tests should be placed in 'blackbox.py'.
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* Try to practice Test-Driven Development. before fixing a bug, write a
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test case so that it does not regress. Similarly for adding a new
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feature: write a test case for a small version of the new feature before
22
starting on the code itself. Check the test fails on the old code, then
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add the feature or fix and check it passes.
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* Before fixing a bug, write a test case so that it does not regress.
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26
* Exceptions should be defined inside bzrlib.errors, so that we can
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see the whole tree at a glance.
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* Module names should always be given fully-qualified,
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i.e. ``bzrlib.hashcache`` not just ``hashcache``.
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* Commands should return non-zero when they encounter circumstances that
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the user should really pay attention to - which includes trivial shell
40
Recommended values are
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1- Conflicts in merge-like operations, or changes are present in
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2- Unrepresentable diff changes (i.e. binary files that we cannot show
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3- An error or exception has occurred.
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37
Evolving interfaces
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38
-------------------
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We have a commitment to 6 months API stability - any supported symbol in a
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release of bzr MUST NOT be altered in any way that would result in
53
breaking existing code that uses it. That means that method names,
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parameter ordering, parameter names, variable and attribute names etc must
55
not be changed without leaving a 'deprecated forwarder' behind. This even
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applies to modules and classes.
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If you wish to change the behaviour of a supported API in an incompatible
59
way, you need to change its name as well. For instance, if I add a optional keyword
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parameter to branch.commit - that's fine. On the other hand, if I add a
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keyword parameter to branch.commit which is a *required* transaction
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object, I should rename the API - i.e. to 'branch.commit_transaction'.
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When renaming such supported API's, be sure to leave a deprecated_method (or
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_function or ...) behind which forwards to the new API. See the
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bzrlib.symbol_versioning module for decorators that take care of the
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details for you - such as updating the docstring, and issuing a warning
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when the old api is used.
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For unsupported API's, it does not hurt to follow this discipline, but its
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not required. Minimally though, please try to rename things so that
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callers will at least get an AttributeError rather than weird results.
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Standard parameter types
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------------------------
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There are some common requirements in the library: some parameters need to be
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unicode safe, some need byte strings, and so on. At the moment we have
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only codified one specific pattern: Parameters that need to be unicode
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should be check via 'bzrlib.osutils.safe_unicode'. This will coerce the
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input into unicode in a consistent fashion, allowing trivial strings to be
83
used for programmer convenience, but not performing unpredictably in the
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presence of different locales.
40
If you change the behaviour of an API in an incompatible way, please
41
be sure to change its name as well. For instance, if I add a keyword
42
parameter to branch.commit - that's fine. On the other hand, if I add
43
a keyword parameter to branch.commit which is a *required* transaction
44
object, I should rename the api - i.e. to 'branch.commit_transaction'.
46
This will prevent users of the old api getting surprising results.
47
Instead, they will get an Attribute error as the api is missing, and
48
will know to update their code. If in doubt, just ask on #bzr.
99
60
bugs should be listed. See the existing entries for an idea of what
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Within each release, entries in the news file should have the most
103
user-visible changes first. So the order should be approximately:
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* changes to existing behaviour - the highest priority because the
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user's existing knowledge is incorrect
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* new features - should be brought to their attention
108
* bug fixes - may be of interest if the bug was affecting them, and
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should include the bug number if any
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* major documentation changes
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* changes to internal interfaces
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People who made significant contributions to each change are listed in
114
parenthesis. This can include reporting bugs (particularly with good
115
details or reproduction recipes), submitting patches, etc.
172
119
(not ``x2y`` as occurs in some old code.)
178
Python destructors (``__del__``) work differently to those of other
179
languages. In particular, bear in mind that destructors may be called
180
immediately when the object apparently becomes unreferenced, or at some
181
later time, or possibly never at all. Therefore we have restrictions on
182
what can be done inside them.
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0. Never use a __del__ method without asking Martin/Robert first.
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1. Never rely on a ``__del__`` method running. If there is code that
187
must run, do it from a ``finally`` block instead.
189
2. Never ``import`` from inside a ``__del__`` method, or you may crash the
192
3. In some places we raise a warning from the destructor if the object
193
has not been cleaned up or closed. This is considered OK: the warning
194
may not catch every case but it's still useful sometimes.
236
In general tests should be placed in a file named test_FOO.py where
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In general tests should be placed in a file named testFOO.py where
237
162
FOO is the logical thing under test. That file should be placed in the
238
163
tests subdirectory under the package being tested.
240
For example, tests for merge3 in bzrlib belong in bzrlib/tests/test_merge3.py.
241
See bzrlib/selftest/test_sampler.py for a template test script.
243
Tests can be written for the UI or for individual areas of the library.
244
Choose whichever is appropriate: if adding a new command, or a new command
245
option, then you should be writing a UI test. If you are both adding UI
246
functionality and library functionality, you will want to write tests for
247
both the UI and the core behaviours. We call UI tests 'blackbox' tests
248
and they are found in bzrlib/tests/blackbox/*.py.
250
When writing blackbox tests please honour the following conventions:
252
1. Place the tests for the command 'name' in
253
bzrlib/tests/blackbox/test_name.py. This makes it easy for developers
254
to locate the test script for a faulty command.
256
2. Use the 'self.run_bzr("name")' utility function to invoke the command
257
rather than running bzr in a subprocess or invoking the
258
cmd_object.run() method directly. This is a lot faster than
259
subprocesses and generates the same logging output as running it in a
260
subprocess (which invoking the method directly does not).
262
3. Only test the one command in a single test script. Use the bzrlib
263
library when setting up tests and when evaluating the side-effects of
264
the command. We do this so that the library api has continual pressure
265
on it to be as functional as the command line in a simple manner, and
266
to isolate knock-on effects throughout the blackbox test suite when a
267
command changes it name or signature. Ideally only the tests for a
268
given command are affected when a given command is changed.
165
For example, tests for merge3 in bzrlib belong in bzrlib/tests/testmerge3.py.
166
See bzrlib/selftest/testsampler.py for a template test script.
272
171
Currently, bzr selftest is used to invoke tests.
273
172
You can provide a pattern argument to run a subset. For example,
274
to run just the blackbox tests, run::
173
to run just the whitebox tests, run::
276
./bzr selftest -v blackbox
175
bzr selftest -v whitebox
279
178
Errors and exceptions
280
179
=====================
282
Errors are handled through Python exceptions. They can represent user
283
errors, environmental errors or program bugs. Sometimes we can't be sure
284
at the time it's raised which case applies. See bzrlib/errors.py for
285
details on the error-handling practices.
292
188
Integer identifier for a revision on the main line of a branch.
293
189
Revision 0 is always the null revision; others are 1-based
294
190
indexes into the branch's revision history.
300
The ``Transport`` layer handles access to local or remote directories.
301
Each Transport object acts like a logical connection to a particular
302
directory, and it allows various operations on files within it. You can
303
*clone* a transport to get a new Transport connected to a subdirectory or
306
Transports are not used for access to the working tree. At present
307
working trees are always local and they are accessed through the regular
308
Python file io mechanisms.
313
Transports work in URLs. Take note that URLs are by definition only
314
ASCII - the decision of how to encode a Unicode string into a URL must be
315
taken at a higher level, typically in the Store. (Note that Stores also
316
escape filenames which cannot be safely stored on all filesystems, but
317
this is a different level.)
319
The main reason for this is that it's not possible to safely roundtrip a
320
URL into Unicode and then back into the same URL. The URL standard
321
gives a way to represent non-ASCII bytes in ASCII (as %-escapes), but
322
doesn't say how those bytes represent non-ASCII characters. (They're not
323
guaranteed to be UTF-8 -- that is common but doesn't happen everywhere.)
325
For example if the user enters the url ``http://example/%e0`` there's no
326
way to tell whether that character represents "latin small letter a with
327
grave" in iso-8859-1, or "latin small letter r with acute" in iso-8859-2
328
or malformed UTF-8. So we can't convert their URL to Unicode reliably.
330
Equally problematic if we're given a url-like string containing non-ascii
331
characters (such as the accented a) we can't be sure how to convert that
332
to the correct URL, because we don't know what encoding the server expects
333
for those characters. (Although this is not totally reliable we might still
334
accept these and assume they should be put into UTF-8.)
336
A similar edge case is that the url ``http://foo/sweet%2Fsour" contains
337
one directory component whose name is "sweet/sour". The escaped slash is
338
not a directory separator. If we try to convert URLs to regular Unicode
339
paths this information will be lost.
341
This implies that Transports must natively deal with URLs; for simplicity
342
they *only* deal with URLs and conversion of other strings to URLs is done
343
elsewhere. Information they return, such as from ``list_dir``, is also in
344
the form of URL components.
350
If you'd like to propose a change, please post to the
351
bazaar-ng@lists.canonical.com list with a patch, bzr changeset, or link to a
352
branch. Please put '[patch]' in the subject so we can pick them out, and
353
include some text explaining the change. Remember to put an update to the NEWS
354
file in your diff, if it makes any changes visible to users or plugin
355
developers. Please include a diff against mainline if you're giving a link to
358
Please indicate if you think the code is ready to merge, or if it's just a
359
draft or for discussion. If you want comments from many developers rather than
360
to be merged, you can put '[rfc]' in the subject lines.
362
Anyone is welcome to review code. There are broadly three gates for
365
* Doesn't reduce test coverage: if it adds new methods or commands,
366
there should be tests for them. There is a good test framework
367
and plenty of examples to crib from, but if you are having trouble
368
working out how to test something feel free to post a draft patch
371
* Doesn't reduce design clarity, such as by entangling objects
372
we're trying to separate. This is mostly something the more
373
experienced reviewers need to help check.
375
* Improves bugs, features, speed, or code simplicity.
377
Code that goes in should pass all three.
379
If you read a patch please reply and say so. We can use a numeric scale
380
of -1, -0, +0, +1, meaning respectively "really don't want it in current
381
form", "somewhat uncomfortable", "ok with me", and "please put it in".
382
Anyone can "vote". (It's not really voting, just a terse expression.)
384
If something gets say two +1 votes from core reviewers, and no
385
vetos, then it's OK to come in. Any of the core developers can bring it
386
into their integration branch, which I'll merge regularly. (If you do
387
so, please reply and say so.)
added
removed
HACKING
