1 @c -*- coding: utf-8; mode: texinfo; -*-
3 @chapter Regression tests
6 * Introduction to regression tests::
7 * Precompiled regression tests::
8 * Compiling regression tests::
10 * Finding the cause of a regression::
11 * Memory and coverage tests::
16 @node Introduction to regression tests
17 @section Introduction to regression tests
19 LilyPond has a complete suite of regression tests that are used
20 to ensure that changes to the code do not break existing behavior.
21 These regression tests comprise small LilyPond snippets that test
22 the functionality of each part of LilyPond.
24 Regression tests are added when new functionality is added to
26 We do not yet have a policy on when it is appropriate to add or
27 modify a regtest when bugs are fixed. Individual developers
28 should use their best judgement until this is clarified during the
29 @ref{Grand Organization Project (GOP)}.
31 The regression tests are compiled using special @code{make}
32 targets. There are three primary uses for the regression
33 tests. First, successful completion of the regression tests means
34 that LilyPond has been properly built. Second, the output of the
35 regression tests can be manually checked to ensure that
36 the graphical output matches the description of the intended
37 output. Third, the regression test output from two different
38 versions of LilyPond can be automatically compared to identify
39 any differences. These differences should then be manually
40 checked to ensure that the differences are intended.
42 Regression tests (@qq{regtests}) are available in precompiled form
43 as part of the documentation. Regtests can also be compiled
44 on any machine that has a properly configured LilyPond build
48 @node Precompiled regression tests
49 @section Precompiled regression tests
51 @subheading Regression test output
53 As part of the release process, the regression tests are run
54 for every LilyPond release. Full regression test output is
55 available for every stable version and the most recent development
58 Regression test output is available in HTML and PDF format. Links
59 to the regression test output are available at the developer's
60 resources page for the version of interest.
62 The latest stable version of the regtests is found at:
65 @uref{http://lilypond.org/doc/stable/input/regression/collated-files.html}
68 The latest development version of the regtests is found at:
71 @uref{http://lilypond.org/doc/latest/input/regression/collated-files.html}
75 @subheading Regression test comparison
77 Each time a new version is released, the regtests are
78 compiled and the output is automatically compared with the
79 output of the previous release. The result of these
80 comparisons is archived online:
83 @uref{http://lilypond.org/test/}
86 Checking these pages is a very important task for the LilyPond project.
87 You are invited to report anything that looks broken, or any case
88 where the output quality is not on par with the previous release,
89 as described in @rweb{Bug reports}.
91 @warning{ The special regression test
92 @file{test-output-distance.ly} will always show up as a
93 regression. This test changes each time it is run, and serves to
94 verify that the regression tests have, in fact, run.}
97 @subheading What to look for
99 The test comparison shows all of the changes that occurred between
100 the current release and the prior release. Each test that has a
101 significant difference in output is displayed, with the old
102 version on the left and the new version on the right.
104 Regression tests whose output is the same for both versions are
105 not shown in the test comparison.
109 Images: green blurs in the new version show the approximate
110 location of elements in the old version.
112 There are often minor adjustments in spacing which do not indicate
116 Log files: show the difference in command-line output.
118 The main thing to examine are any changes in page counts -- if a
119 file used to fit on 1 page but now requires 4 or 5 pages,
120 something is suspicious!
123 Profile files: give information about
124 TODO? I don't know what they're for.
129 The automatic comparison of the regtests checks the LilyPond
130 bounding boxes. This means that Ghostscript changes and changes
131 in lyrics or text are not found.
134 @node Compiling regression tests
135 @section Compiling regression tests
137 Developers may wish to see the output of the complete regression
138 test suite for the current version of the source repository
139 between releases. Current source code is available; see
140 @ref{Working with source code}. Then you will need
141 to build the LilyPond binary; see @ref{Compiling LilyPond}.
143 Uninstalling the previous LilyPond version is not necessary, nor is
144 running @code{make install}, since the tests will automatically be
145 compiled with the LilyPond binary you have just built in your source
148 From this point, the regtests are compiled with:
154 If you have a multi-core machine you may want to use the @option{-j}
155 option and @var{CPU_COUT} variable, as
156 described in @ref{Saving time with CPU_COUNT}.
157 For a quad-core processor the complete command would be:
160 make -j5 CPU_COUNT=5 test
163 The regtest output will then be available in
164 @file{input/regression/out-test}.
165 @file{input/regression/out-test/collated-examples.html}
166 contains a listing of all the regression tests that were run,
167 but none of the images are included. Individual images are
168 also available in this directory.
170 The primary use of @samp{make@tie{}test} is to verify that the
171 regression tests all run without error. The regression test
172 page that is part of the documentation is created only when the
173 documentation is built, as described in @ref{Generating documentation}.
174 Note that building the documentation requires more installed components
175 than building the source code, as described in
176 @ref{Requirements for building documentation}.
179 @node Regtest comparison
180 @section Regtest comparison
182 Before modified code is committed to master, a regression test
183 comparison must be completed to ensure that the changes have
184 not caused problems with previously working code. The comparison
185 is made automatically upon compiling the regression test suite
191 Run @code{make} with current git master without any of your changes.
194 Before making changes to the code, establish a baseline for the comparison by
195 going to the @file{lilypond-git/build/} directory and running:
202 Make your changes, or apply the patch(es) to consider.
205 Compile the source with @samp{make} as usual.
208 Check for unintentional changes to the regtests:
214 After this has finished, a regression test comparison will be
215 available (relative to the current @file{build/} directory) at:
218 out/test-results/index.html
221 For each regression test that differs between the baseline and the
222 changed code, a regression test entry will displayed. Ideally,
223 the only changes would be the changes that you were working on.
224 If regressions are introduced, they must be fixed before
228 The special regression test @file{test-output-distance.ly} will always
229 show up as a regression. This test changes each time it is run, and
230 serves to verify that the regression tests have, in fact, run.}
233 If you are happy with the results, then stop now.
235 If you want to continue programming, then make any additional code
236 changes, and continue.
239 Compile the source with @samp{make} as usual.
242 To re-check files that differed between the initial
243 @samp{make@tie{}test-baseline} and your post-changes
244 @samp{make@tie{}check}, run:
250 This updates the regression list at @file{out/test-results/index.html}.
251 It does @emph{not} redo @file{test-output-distance.ly}.
254 When all regressions have been resolved, the output list will be empty.
257 Once all regressions have been resolved, a final check should be completed
265 This cleans the results of the previous @samp{make@tie{}check}, then does the
266 automatic regression comparison again.
271 Once a test baseline has been established, there is no need to run it again
272 unless git master changed. In other words, if you work with several branches
273 and want to do regtests comparison for all of them, you can
274 @code{make test-baseline} with git master, checkout some branch,
275 @code{make} and @code{make check} it, then switch to another branch,
276 @code{make} and @code{make check} it without doing @code{make test-baseline}
280 @node Finding the cause of a regression
281 @section Finding the cause of a regression
283 Git has special functionality to help tracking down the exact
284 commit which causes a problem. See the git manual page for
285 @code{git bisect}. This is a job that non-programmers can do,
286 although it requires familiarity with git, ability to compile
287 LilyPond, and generally a fair amount of technical knowledge. A
288 brief summary is given below, but you may need to consult other
289 documentation for in-depth explanations.
291 Even if you are not familiar with git or are not able to compile
292 LilyPond you can still help to narrow down the cause of a
293 regression simply by downloading the binary releases of different
294 LilyPond versions and testing them for the regression. Knowing
295 which version of LilyPond first exhibited the regression is
296 helpful to a developer as it shortens the @code{git bisect}
299 Once a problematic commit is identified, the programmers' job is
300 much easier. In fact, for most regression bugs, the majority of
301 the time is spent simply finding the problematic commit.
303 More information is in @ref{Regression tests}.
305 @subheading git bisect setup
307 We need to set up the bisect for each problem we want to
310 Suppose we have an input file which compiled in version 2.13.32,
311 but fails in version 2.13.38 and above.
322 Give it the earliest known bad tag:
325 git bisect bad release/2.13.38-1
328 (you can see tags with: @code{git tag} )
331 Give it the latest known good tag:
334 git bisect good release/2.13.32-1
337 You should now see something like:
339 Bisecting: 195 revisions left to test after this (roughly 8 steps)
340 [b17e2f3d7a5853a30f7d5a3cdc6b5079e77a3d2a] Web: Announcement
341 update for the new @qq{LilyPond Report}.
346 @subheading git bisect actual
358 Test your input file:
361 out/bin/lilypond test.ly
369 Does it crash, or is the output bad? If so:
376 Does your input file produce good output? If so:
385 Once the exact problem commit has been identified, git will inform
386 you with a message like:
389 6d28aebbaaab1be9961a00bf15a1ef93acb91e30 is the first bad commit
390 %%% ... blah blah blah ...
393 If there is still a range of commits, then git will automatically
394 select a new version for you to test. Go to step #1.
398 @subheading Recommendation: use two terminal windows
402 One window is open to the @code{build/} directory, and alternates
403 between these commands:
407 out/bin/lilypond test.ly
411 One window is open to the top source directory, and alternates
412 between these commands:
422 @node Memory and coverage tests
423 @section Memory and coverage tests
425 In addition to the graphical output of the regression tests, it is
426 possible to test memory usage and to determine how much of the source
427 code has been exercised by the tests.
429 @subheading Memory usage
431 For tracking memory usage as part of this test, you will need
432 GUILE CVS; especially the following patch:
434 @uref{http://www.lilypond.org/vc/old/gub.darcs/patches/guile-1.9-gcstats.patch}.
437 @subheading Code coverage
439 For checking the coverage of the test suite, do the following
442 ./scripts/auxiliar/build-coverage.sh
443 @emph{# uncovered files, least covered first}
444 ./scripts/auxiliar/coverage.py --summary out-cov/*.cc
445 @emph{# consecutive uncovered lines, longest first}
446 ./scripts/auxiliar/coverage.py --uncovered out-cov/*.cc
451 @section MusicXML tests
454 LilyPond comes with a complete set of regtests for the
455 @uref{http://www.musicxml.org/,MusicXML} language. Originally
456 developed to test @samp{musicxml2ly}, these regression tests
457 can be used to test any MusicXML implementation.
459 The MusicXML regression tests are found at
460 @file{input/regression/musicxml/}.
462 The output resulting from running these tests
463 through @samp{muscxml2ly} followed by @samp{lilypond} is
464 available in the LilyPond documentation:
467 @uref{http://lilypond.org/doc/latest/input/regression/musicxml/collated-files}