BTest - A Simple Driver for Basic Unit Tests¶
The btest is a simple framework for writing unit tests. Freely
borrowing some ideas from other packages, it’s main objective is to
provide an easy-to-use, straightforward driver for a suite of
shell-based tests. Each test consists of a set of command lines that
will be executed, and success is determined based on their exit
codes. btest comes with some additional tools that can be used
within such tests to compare output against a previously established
baseline.
Contents
Download¶
You can find the latest BTest release for download at https://www.zeek.org/download.
BTest’s git repository is located at https://github.com/zeek/btest
This document describes BTest 0.58-5. See the CHANGES
file for version history.
Prerequisites¶
BTest has the following prerequisites:
- Python version >= 2.6.
- Bash (note that on FreeBSD, bash is not installed by default).
BTest has the following optional prerequisites to enable additional functionality:
- Sphinx.
- perf (Linux only). Note that on Debian/Ubuntu, you also need to install the “linux-tools” package.
Installation¶
Installation is simple and standard:
tar xzvf btest-*.tar.gz
cd btest-*
python setup.py install
This will install a few scripts: btest is the main driver program,
and there are a number of further helper scripts that we discuss below
(including btest-diff, which is a tool for comparing output to a
previously established baseline).
Writing a Simple Test¶
In the most simple case, btest simply executes a set of command
lines, each of which must be prefixed with @TEST-EXEC:
> cat examples/t1
@TEST-EXEC: echo "Foo" | grep -q Foo
@TEST-EXEC: test -d .
> btest examples/t1
examples.t1 ... ok
The test passes as both command lines return success. If one of them didn’t, that would be reported:
> cat examples/t2
@TEST-EXEC: echo "Foo" | grep -q Foo
@TEST-EXEC: test -d DOESNOTEXIST
> btest examples/t2
examples.t2 ... failed
Usually you will just run all tests found in a directory:
> btest examples
examples.t1 ... ok
examples.t2 ... failed
1 test failed
Why do we need the @TEST-EXEC: prefixes? Because the file
containing the test can simultaneously act as its input. Let’s
say we want to verify a shell script:
> cat examples/t3.sh
# @TEST-EXEC: sh %INPUT
ls /etc | grep -q passwd
> btest examples/t3.sh
examples.t3 ... ok
Here, btest is executing (something similar to) sh
examples/t3.sh, and then checks the return value as usual. The
example also shows that the @TEST-EXEC prefix can appear
anywhere, in particular inside the comment section of another
language.
Now, let’s say we want to check the output of a program, making sure
that it matches what we expect. For that, we first add a command
line to the test that produces the output we want to check, and then
run btest-diff to make sure it matches a previously recorded
baseline. btest-diff is itself just a script that returns
success if the output is as expected, and failure otherwise. In the
following example, we use an awk script as a fancy way to print all
file names starting with a dot in the user’s home directory. We
write that list into a file called dots and then check whether
its content matches what we know from last time:
> cat examples/t4.awk
# @TEST-EXEC: ls -a $HOME | awk -f %INPUT >dots
# @TEST-EXEC: btest-diff dots
/^\.+/ { print $1 }
Note that each test gets its own little sandbox directory when run,
so by creating a file like dots, you aren’t cluttering up
anything.
The first time we run this test, we need to record a baseline:
> btest -U examples/t4.awk
Now, btest-diff has remembered what the dots file should
look like:
> btest examples/t4.awk
examples.t4 ... ok
> touch ~/.NEWDOTFILE
> btest examples/t4.awk
examples.t4 ... failed
1 test failed
If we want to see what exactly the unexpected change is that was
introduced to dots, there’s a diff mode for that:
> btest -d examples/t4.awk
examples.t4 ... failed
% 'btest-diff dots' failed unexpectedly (exit code 1)
% cat .diag
== File ===============================
[... current dots file ...]
== Diff ===============================
--- /Users/robin/work/binpacpp/btest/Baseline/examples.t4/dots
2010-10-28 20:11:11.000000000 -0700
+++ dots 2010-10-28 20:12:30.000000000 -0700
@@ -4,6 +4,7 @@
.CFUserTextEncoding
.DS_Store
.MacOSX
+.NEWDOTFILE
.Rhistory
.Trash
.Xauthority
=======================================
% cat .stderr
[... if any of the commands had printed something to stderr, that would follow here ...]
Once we delete the new file, we are fine again:
> rm ~/.NEWDOTFILE
> btest -d examples/t4.awk
examples.t4 ... ok
That’s already the main functionality that the btest package
provides. In the following, we describe a number of further options
extending/modifying this basic approach.
Reference¶
Command Line Usage¶
btest must be started with a list of tests and/or directories
given on the command line. In the latter case, the default is to
recursively scan the directories and assume all files found to be
tests to perform. It is however possible to exclude specific files and
directories by specifying a suitable configuration file.
btest returns exit code 0 if all tests have successfully passed,
and 1 otherwise.
btest accepts the following options:
-a ALTERNATIVE, --alternative=ALTERNATIVE Activates an alternative configuration defined in the configuration file. Multiple alternatives can be given as a comma-separated list (in this case, all specified tests are run once for each specified alternative). If ALTERNATIVEis-that refers to running with the standard setup, which can be used to run tests both with and without alternatives by giving both.-A, --show-all Shows an output line for all tests that were run (this includes tests that passed, failed, or were skipped), rather than only failed tests. Note that this option has no effect when btest’s stdout is not a TTY (because all tests are shown in that case). -b, --brief Does not output anything for tests which pass. If all tests pass, there will not be any output at all except final summary information. -c CONFIG, --config=CONFIG Specifies an alternative configuration file to use. If not specified, the default is to use a file called btest.cfgif found in the current directory. An alternative way to specify a different config file is with theBTEST_CFGenvironment variable (however, the command-line option overridesBTEST_CFG).-d, --diagnostics Reports diagnostics for all failed tests. The diagnostics include the command line that failed, its output to standard error, and potential additional information recorded by the command line for diagnostic purposes (see @TEST-EXEC below). In the case of btest-diff, the latter is thediffbetween baseline and actual output.-D, --diagnostics-all Reports diagnostics for all tests, including those which pass. -f DIAGFILE, --file-diagnostics=DIAGFILE Writes diagnostics for all failed tests into the given file. If the file already exists, it will be overwritten. -g GROUPS, --groups=GROUPS Runs only tests assigned to the given test groups, see @TEST-GROUP. Multiple groups can be given as a comma-separated list. Specifying groups with a leading -leads to all tests to run that are not not part of them. Specifying a sole-as a group name selects all tests that do not belong to any group. (Note that if you combine these variants to create ambigious situations, it’s left undefined which tests will end up running).-j THREADS, --jobs=THREADS Runs up to the given number of tests in parallel. If no number is given, BTest substitutes the number of available CPU cores as reported by the OS.
By default, BTest assumes that all tests can be executed concurrently without further constraints. One can however ensure serialization of subsets by assigning them to the same serialization set, see @TEST-SERIALIZE.
-q, --quiet Suppress information output other than about failed tests. If all tests pass, there will not be any output at all. -r, --rerun Runs only tests that failed last time. After each execution (except when updating baselines), BTest generates a state file that records the tests that have failed. Using this option on the next run then reads that file back in and limits execution to those tests found in there. -R FORMAT, --documentation=FORMAT Generates a reference of all tests and prints that to standard output. The output can be of two types, specified by FORMAT:rstprints reStructuredText, andmdprints Markdown. In the output each test includes the documentation string that’s defined for it through@TEST-DOC.-t, --tmp-keep Does not delete any temporary files created for running the tests (including their outputs). By default, the temporary files for a test will be located in .tmp/<test>/, where<test>is the relative path of the test file with all slashes replaced with dots and the file extension removed (e.g., the files forexample/t3.shwill be in.tmp/example.t3).-T, --update-times Record new timing baselines for the current host for tests that have @TEST-MEASURE-TIME. Tests are run as normal except that the timing measurements are recorded as the new baseline instead of being compared to a previous baseline. -U, --update-baseline Records a new baseline for all btest-diffcommands found in any of the specified tests. To do this, all tests are run as normal except that whenbtest-diffis executed, it does not compute a diff but instead considers the given file to be authoritative and records it as the version to compare with in future runs.-u, --update-interactive Each time a btest-diffcommand fails in any tests that are run, btest will stop and ask whether or not the user wants to record a new baseline.-v, --verbose Shows all test command lines as they are executed. -w, --wait Interactively waits for <enter>after showing diagnostics for a test.-x FILE, --xml=FILE Records test results in JUnit XML format to the given file. If the file exists already, it is overwritten.
Configuration¶
Specifics of btest’s execution can be tuned with a configuration
file, which by default is btest.cfg if that’s found in the
current directory. It can alternatively be specified with the
--config command line option, or a BTEST_CFG environment
variable. The configuration file is
“INI-style”, and an example comes with the distribution, see
btest.cfg.example. A configuration file has one main section,
btest, that defines most options; as well as an optional section
for defining environment variables and further optional sections
for defining alternatives.
Note that all paths specified in the configuration file are relative
to btest’s base directory. The base directory is either the
one where the configuration file is located if such is given/found,
or the current working directory if not. One can also override it
explicitly by setting the environment variable BTEST_TEST_BASE.
When setting values for
configuration options, the absolute path to the base directory is
available by using the macro %(testbase)s (the weird syntax is
due to Python’s ConfigParser class).
Furthermore, all values can use standard “backtick-syntax” to
include the output of external commands (e.g., xyz=`echo test`).
Note that the backtick expansion is performed after any %(..)
have already been replaced (including within the backticks).
Options¶
The following options can be set in the btest section of the
configuration file:
TestDirs- A space-separated list of directories to search for tests. If defined, one doesn’t need to specify any tests on the command line.
TmpDir- A directory where to create temporary files when running tests.
By default, this is set to
%(testbase)s/.tmp. BaselineDir- A directory where to store the baseline files for
btest-diff(note that the actual baseline files will be in test-specific subdirectories of this directory). By default, this is set to%(testbase)s/Baseline. IgnoreDirsA space-separated list of relative directory names to ignore when scanning test directories recursively. Default is empty.
An alternative way to ignore a directory is placing a file
.btest-ignorein it.IgnoreFilesA space-separated list of filename globs matching files to ignore when scanning given test directories recursively. Default is empty.
An alternative way to ignore a file is by placing
@TEST-IGNOREin it.StateFile- The name of the state file to record the names of failing tests. Default is
.btest.failed.dat. Initializer- An executable that will be executed before each test. It runs in the same directory as the test itself will and receives the name of the test as its parameter. The return value indicates whether the test should continue; if false, the test will be considered failed. By default, there’s no initializer set.
Finalizer- An executable that will be executed each time any test has successfully run. It runs in the same directory as the test itself and receives the name of the test as its parameter. The return value indicates whether the test should indeed be considered successful. By default, there’s no finalizer set.
PartFinalizer- An executable that will be executed each time a test part has
successfully run. This operates similarly to
Finalizerexcept that it runs after each test part rather than only at completion of the full test. See parts for more about test parts. CommandPrefix- Changes the naming of all
btestcommands by replacing the@TEST-prefix with a custom string. For example, withCommandPrefix=$TEST-, the@TEST-EXECcommand becomes$TEST-EXEC. TimingBaselineDir- A directory where to store the host-specific timing baseline
files. By default, this is set to
%(testbase)s/Baseline/_Timing. TimingDeltaPerc- A value defining the timing deviation percentage that’s tolerated for a test before it’s considered failed. Default is 1.0 (which means a 1.0% deviation is tolerated by default).
PerfPath- Specifies a path to the
perftool, which is used on Linux to measure the execution times of tests. By default, BTest searches forperfinPATH. PortRange- Specifies a port range like “10000-11000” to use in conjuction with
@TEST-PORTcommands. Port assignments will be restricted to this range. The default range is “1024-65535”.
Environment Variables¶
A special section environment defines environment variables that
will be propagated to all tests:
[environment]
CFLAGS=-O3
PATH=%(testbase)s/bin:%(default_path)s
Note how PATH can be adjusted to include local scripts: the
example above prefixes it with a local bin/ directory inside the
base directory, using the predefined default_path macro to refer
to the PATH as it is set by default.
Furthermore, by setting PATH to include the btest
distribution directory, one could skip the installation of the
btest package.
Alternatives¶
BTest can run a set of tests with different settings than it would normally use by specifying an alternative configuration. Currently, three things can be adjusted:
- Further environment variables can be set that will then be available to all the commands that a test executes.
- Filters can modify an input file before a test uses it.
- Substitutions can modify command lines executed as part of a test.
We discuss the three separately in the following. All of them are
defined by adding sections [<type>-<name>] where <type>
corresponds to the type of adjustment being made and <name> is the
name of the alternative. Once at least one section is defined for a
name, that alternative can be enabled by BTest’s --alternative
flag.
Environment Variables¶
An alternative can add further environment variables by defining an
[environment-<name>] section:
[environment-myalternative]
CFLAGS=-O3
Running btest with --alternative=myalternative will now make
the CFLAGS environment variable available to all commands
executed.
As a special case, one can override BTEST_TEST_BASE inside an
alternative’s environment section, and it will not only be passed on
to child processes, but also apply to the btest process itself.
That way, one can switch to a different test base directory for an
alternative.
Filters¶
Filters are a transparent way to adapt the input to a specific test
command before it is executed. A filter is defined by adding a section
[filter-<name>] to the configuration file. This section must have
exactly one entry, and the name of that entry is interpreted as the
name of a command whose input is to be filtered. The value of that
entry is the name of a filter script that will be run with two
arguments representing input and output files, respectively. Example:
[filter-myalternative]
cat=%(testbase)s/bin/filter-cat
Once the filter is activated by running btest with
--alternative=myalternative, every time a @TEST-EXEC: cat
%INPUT is found, btest will first execute (something similar to)
%(testbase)s/bin/filter-cat %INPUT out.tmp, and then subsequently
cat out.tmp (i.e., the original command but with the filtered
output). In the simplest case, the filter could be a no-op in the
form cp $1 $2.
Note
There are a few limitations to the filter concept currently:
- Filters are always fed with
%INPUTas their first argument. We should add a way to filter other files as well. - Filtered commands are only recognized if they are directly
starting the command line. For example,
@TEST-EXEC: ls | cat >outoutwould not trigger the example filter above. - Filters are only executed for
@TEST-EXEC, not for@TEST-EXEC-FAIL.
Substitutions¶
Substitutions are similar to filters, yet they do not adapt the input
but the command line being executed. A substitution is defined by
adding a section [substitution-<name>] to the configuration file.
For each entry in this section, the entry’s name specifies the
command that is to be replaced with something else given as its value.
Example:
[substitution-myalternative]
gcc=gcc -O2
Once the substitution is activated by running btest with
--alternative=myalternative, every time a @TEST-EXEC executes
gcc, that is replaced with gcc -O2. The replacement is simple
string substitution so it works not only with commands but anything
found on the command line; it however only replaces full words, not
subparts of words.
Writing Tests¶
btest scans a test file for lines containing keywords that
trigger certain functionality. Currently, the following keywords are
supported:
@TEST-EXEC: <cmdline>Executes the given command line and aborts the test if it returns an error code other than zero. The
<cmdline>is passed to the shell and thus can be a pipeline, use redirection, and any environment variables specified in<cmdline>will be expanded, etc.When running a test, the current working directory for all command lines will be set to a temporary sandbox (and will be deleted later).
There are two macros that can be used in
<cmdline>:%INPUTwill be replaced with the full pathname of the file defining the test (this file is in a temporary sandbox directory and is a copy of the original test file); and%DIRwill be replaced with the full pathname of the directory where the test file is located (note that this is the directory where the original test file is located, not the directory where the%INPUTfile is located). The latter can be used to reference further files also located there.In addition to environment variables defined in the configuration file, there are further ones that are passed into the commands:
TEST_DIAGNOSTICS- A file where further diagnostic information can be saved
in case a command fails (this is also where
btest-diffstores its diff). If this file exists, then the--diagnostics-allor--diagnosticsoptions will show this file (for the latter option, only if a command fails). TEST_MODE- This is normally set to
TEST, but will beUPDATEifbtestis run with--update-baseline, orUPDATE_INTERACTIVEif run with--update-interactive. TEST_BASELINE- The name of a directory where the command can save permanent
information across
btestruns. (This is wherebtest-diffstores its baseline inUPDATEmode.) TEST_NAME- The name of the currently executing test.
TEST_VERBOSE- The path of a file where the test can record further
information about its execution that will be included with
btest’s
--verboseoutput. This is for further tracking the execution of commands and should generally generate output that follows a line-based structure. TEST_BASE- The btest base directory, i.e., the directory where
btest.cfgis located. TEST_PART- The test part number (see parts for more about test parts).
Note
If a command returns the special exit code 100, the test is considered failed, however subsequent test commands within the current test are still run.
btest-diffuses this special exit code to indicate that no baseline has yet been established.If a command returns the special exit code 200, the test is considered failed and all further tests are aborted.
btest-diffuses this special exit code when btest is run with the--update-interactiveoption and the user chooses to abort the tests when prompted to record a new baseline.@TEST-EXEC-FAIL: <cmdline>- Like
@TEST-EXEC, except that this expects the command to fail, i.e., the test is aborted when the return code is zero. @TEST-REQUIRES: <cmdline>- Defines a condition that must be met for the test to be executed. The given command line will be run before any of the actual test commands, and it must return success for the test to continue. If it does not return success, the rest of the test will be skipped but doing so will not be considered a failure of the test. This allows to write conditional tests that may not always make sense to run, depending on whether external constraints are satisfied or not (say, whether a particular library is available). Multiple requirements may be specified and then all must be met for the test to continue.
@TEST-ALTERNATIVE: <alternative>- Runs this test only for the given alternative (see alternative).
If
<alternative>isdefault, the test executes when BTest runs with no alternative given (which however is the default anyway). @TEST-NOT-ALTERNATIVE: <alternative>- Ignores this test for the given alternative (see alternative).
If
<alternative>isdefault, the test is ignored if BTest runs with no alternative given. @TEST-COPY-FILE: <file>- Copy the given file into the test’s directory before the test is
run. If
<file>is a relative path, it’s interpreted relative to the BTest’s base directory. Environment variables in<file>will be replaced if enclosed in${..}. This command can be given multiple times. @TEST-START-NEXTThis is a short-cut for defining multiple test inputs in the same file, all executing with the same command lines. When
@TEST-START-NEXTis encountered, the test file is initially considered to end at that point, and all@TEST-EXEC-*are run with an%INPUTtruncated accordingly. Afterwards, a new%INPUTis created with everything following the@TEST-START-NEXTmarker, and the same commands are run again (further@TEST-EXEC-*will be ignored). The effect is that a single file can actually define two tests, and thebtestoutput will enumerate them:> cat examples/t5.sh # @TEST-EXEC: cat %INPUT | wc -c >output # @TEST-EXEC: btest-diff output This is the first test input in this file. # @TEST-START-NEXT ... and the second. > ./btest -D examples/t5.sh examples.t5 ... ok % cat .diag == File =============================== 119 [...] examples.t5-2 ... ok % cat .diag == File =============================== 22 [...]
Multiple
@TEST-START-NEXTcan be used to create more than two tests per file.@TEST-START-FILE <file>This is used to include an additional input file for a test right inside the test file. All lines following the keyword line will be written into the given file until a line containing
@TEST-END-FILEis found. The lines containing@TEST-START-FILEand@TEST-END-FILE, and all lines in between, will be removed from the test’s %INPUT. Example:> cat examples/t6.sh # @TEST-EXEC: awk -f %INPUT <foo.dat >output # @TEST-EXEC: btest-diff output { lines += 1; } END { print lines; } @TEST-START-FILE foo.dat 1 2 3 @TEST-END-FILE > btest -D examples/t6.sh examples.t6 ... ok % cat .diag == File =============================== 3
Multiple such files can be defined within a single test.
Note that this is only one way to use further input files. Another is to store a file in the same directory as the test itself, making sure it’s ignored via
IgnoreFiles, and then refer to it via%DIR/<name>.@TEST-IGNORE- This is used to indicate that this file should be skipped (i.e., no
test commands in this file will be executed). An alternative way to
ignore files is by using the
IgnoreFilesoption in the btest configuration file. @TEST-DOC: <docstring>- Associates a documentation string with the test. These strings
get included into the output of the
--documentationoption.
@TEST-GROUP: <group>- Assigns the test to a group of name
<group>. By using option-gone can limit execution to all tests that belong to a given group (or a set of groups).
@TEST-SERIALIZE: <set>- When using option
-jto parallelize execution, all tests that specify the same serialization set are guaranteed to run sequentially.<set>is an arbitrary user-chosen string.
@TEST-PORT: <env>- Assign an available TCP port number to an environment variable
that is accessible from the running test process.
<env>is an arbitrary user-chosen string that will be set to the next available TCP port number. Availability is based on checking successful binding of the port on IPv4 INADDR_ANY and also restricted to the range specified by thePortRangeoption. IPv6 is not supported. Note that using the-joption to parallelize execution will work such that unique/available port numbers are assigned between concurrent tests, however there is still a potential race condition for external processes to claim a port before the test actaully runs and claims it for itself. @TEST-KNOWN-FAILUREMarks a test as known to currently fail. This only changes BTest’s output, which upon failure will indicate that that is expected; it won’t change the test’s processing otherwise. The keyword doesn’t take any arguments but one could add a descriptive text, as in
.. @TEST-KNOWN-FAILURE: We know this fails because ....
@TEST-MEASURE-TIME- Measures execution time for this test and compares it to a previously established timing baseline. If it deviates significantly, the test will be considered failed.
Splitting Tests into Parts¶
One can split a single test across multiple files by adding a
numerical #<n> postfix to their names, where each <n>
represents a separate part of the test. btest will combine all of
a test’s parts in numerical order and execute them subsequently within
the same sandbox. Example:
> cat examples/t7.sh#1
# @TEST-EXEC: echo Part 1 - %INPUT >>output
> cat examples/t7.sh#2
# @TEST-EXEC: echo Part 2 - %INPUT >>output
> cat examples/t7.sh#3
# @TEST-EXEC: btest-diff output
> btest -D examples/t7.sh
examples.t7 ... ok
% cat .diag
== File ===============================
Part 1 - /Users/robin/bro/docs/aux/btest/.tmp/examples.t7/t7.sh#1
Part 2 - /Users/robin/bro/docs/aux/btest/.tmp/examples.t7/t7.sh#2
Note how output contains the output of both t7.sh#1 and t7.sh#2,
however in each case %INPUT refers to the corresponding part. For
the first part of a test, one can also omit the #1 postfix in the filename.
Canonifying Diffs¶
btest-diff has the capability to filter its input through an
additional script before it compares the current version with the
baseline. This can be useful if certain elements in an output are
expected to change (e.g., timestamps). The filter can then
remove/replace these with something consistent. To enable such
canonification, set the environment variable
TEST_DIFF_CANONIFIER to a script reading the original version
from stdin and writing the canonified version to stdout. Note that
both baseline and current output are passed through the filter
before their differences are computed.
Running Processes in the Background¶
Sometimes processes need to be spawned in the background for a test,
in particular if multiple processes need to cooperate in some fashion.
btest comes with two helper scripts to make life easier in such a
situation:
btest-bg-run <tag> <cmdline>- This is a script that runs
<cmdline>in the background, i.e., it’s like usingcmdline &in a shell script. Test execution continues immediately with the next command. Note that the spawned command is not run in the current directory, but instead in a newly created sub-directory called<tag>. This allows spawning multiple instances of the same process without needing to worry about conflicting outputs. If you want to access a command’s output later, like withbtest-diff, use<tag>/foo.logto access it. btest-bg-wait [-k] <timeout>- This script waits for all processes previously spawned via
btest-bg-runto finish. If any of them exits with a non-zero return code,btest-bg-waitdoes so as well, indicating a failed test.<timeout>is mandatory and gives the maximum number of seconds to wait for any of the processes to terminate. If any process hasn’t done so when the timeout expires, it will be killed and the test is considered to be failed as long as-kis not given. If-kis given, pending processes are still killed but the test continues normally, i.e., non-termination is not considered a failure in this case. This script also collects the processes’ stdout and stderr outputs for diagnostics output.
Displaying Progress¶
For long-running tests it can be helpful to display progress messages during their execution so that one sees where the test is currently at. There’s a helper script, btest-progress, to facilitate that. The script receives a custom message as its sole argument. When executed while a test is running, btest will display that message in real-time in its standard and verbose outputs.
Example usage:
# @TEST-EXEC: bash %INPUT
btest-progress Stage 1
sleep 1
btest-progress Stage 2
sleep 1
btest-progress Stage 3
sleep 1
When the tests execute, btest will then show these three messages
successively. By default, btest-progress also prints the messages
to the test’s standard output and standard error. That can be suppressed by
adding an option -q to the invocation.
Timing Execution¶
btest can time execution of tests and report significant
deviations from past runs. As execution time is inherently
system-specific it keeps separate per-host timing baselines for that.
Furthermore, as time measurements tend to make sense only for
individual, usually longer running tests, they are activated on per
test basis by adding a @TEST-MEASURE-TIME directive. The test
will then execute as usual yet also record the duration for which it
executes. After the timing baselines are created (with the --update-times
option), further runs on the same host will compare their times against that
baseline and declare a test failed if it deviates by more than, by
default, 1%. (To tune the behaviour, look at the Timing* options.)
If a test requests measurement but BTest can’t find a timing baseline
or the necessary tools to perform timing measurements, then it will
ignore the request.
As timing for a test can deviate quite a bit even on the same host,
BTest does not actually measure time but the number of CPU
instructions that a test executes, which tends to be more stable.
That however requires the right tools to be in place. On Linux, BTest
leverages perf. By default, BTest
will search for perf in the PATH; you can specify a different
path to the binary by setting PerfPath in btest.cfg.
Integration with Sphinx¶
btest comes with an extension module for the documentation framework
Sphinx. The extension module provides two
new directives called btest and btest-include. The btest
directive allows writing a test directly inside a Sphinx document, and
then the output from the test’s command is included in the generated
documentation. The btest-include directive allows for literal text
from another file to be included in the generated documentation.
The tests from both directives can also be run externally and will catch
if any changes to the included content occur. The following walks
through setting this up.
Configuration¶
First, you need to tell Sphinx a base directory for the btest
configuration as well as a directory in there where to store tests
it extracts from the Sphinx documentation. Typically, you’d just
create a new subdirectory tests in the Sphinx project for the
btest setup and then store the tests in there in, e.g.,
doc/:
cd <sphinx-root>
mkdir tests
mkdir tests/doc
Then add the following to your Sphinx conf.py:
extensions += ["btest-sphinx"]
btest_base="tests" # Relative to Sphinx-root.
btest_tests="doc" # Relative to btest_base.
Next, create a btest.cfg in tests/ as usual and add
doc/ to the TestDirs option. Also, add a finalizer to btest.cfg:
[btest]
...
PartFinalizer=btest-diff-rst
Including a Test into a Sphinx Document¶
The btest extension provides a new directive to include a test
inside a Sphinx document:
.. btest:: <test-name>
<test content>
Here, <test-name> is a custom name for the test; it will be
stored in btest_tests under that name (with a file extension of
.btest). <test content> is just a standard test as you would
normally put into one of the TestDirs. Example:
.. btest:: just-a-test
@TEST-EXEC: expr 2 + 2
When you now run Sphinx, it will (1) store the test content into
tests/doc/just-a-test.btest (assuming the above path layout), and (2)
execute the test by running btest on it. You can then run
btest manually in tests/ as well and it will execute the test
just as it would in a standard setup. If a test fails when Sphinx runs
it, there will be a corresponding error and include the diagnostic output
into the document.
By default, nothing else will be included into the generated
documentation, i.e., the above test will just turn into an empty text
block. However, btest comes with a set of scripts that you can use
to specify content to be included. As a simple example,
btest-rst-cmd <cmdline> will execute a command and (if it
succeeds) include both the command line and the standard output into
the documentation. Example:
.. btest:: another-test
@TEST-EXEC: btest-rst-cmd echo Hello, world!
When running Sphinx, this will render as:
# echo Hello, world!
Hello, world!
The same <test-name> can be used multiple times, in which case
each entry will become one part of a joint test. btest will
execute all parts subsequently within a single sandbox, and earlier
results will thus be available to later parts.
When running btest manually in tests/, the PartFinalizer we
added to btest.cfg (see above) compares the generated reST code
with a previously established baseline, just like btest-diff does
with files. To establish the initial baseline, run btest -u, like
you would with btest-diff.
Scripts¶
The following Sphinx support scripts come with btest:
btest-rst-cmd [options] <cmdline>
By default, this executes
<cmdline>and includes both the command line itself and its standard output into the generated documentation (but only if the command line succeeds). See above for an example.This script provides the following options:
-c ALTERNATIVE_CMDLINE Show ALTERNATIVE_CMDLINEin the generated documentation instead of the one actually executed. (It still runs the<cmdline>given outside the option.)-d Do not actually execute <cmdline>; just format it for the generated documentation and include no further output.-f FILTER_CMD Pipe the command line’s output through FILTER_CMDbefore including. If-ris given, it filters the file’s content instead of stdout.-o Do not include the executed command into the generated documentation, just its output. -r FILE Insert FILEinto output instead of stdout. TheFILEmust be created by a previous@TEST-EXECor@TEST-COPY-FILE.-n N Include only Nlines of output, adding a[...]marker if there’s more.
btest-rst-include [options] <file>
Includes
<file>inside a code block. The<file>must be created by a previous@TEST-EXECor@TEST-COPY-FILE.This script provides the following options:
-n N Include only Nlines of output, adding a[...]marker if there’s more.
btest-rst-pipe <cmdline>
Executes<cmdline>, includes its standard output inside a code block (but only if the command line succeeds). Note that this script does not include the command line itself into the code block, just the output.
Note
All these scripts can be run directly from the command line to show the reST code they generate.
Note
btest-rst-cmd can do everything the other scripts provide if
you give it the right options. In fact, the other scripts are
provided just for convenience and leverage btest-rst-cmd
internally.
Including Literal Text¶
The btest Sphinx extension module also provides a directive
btest-include that functions like literalinclude (including all
its options) but also creates a test checking the included content for
changes. As one further extension, the directive expands environment
variables of the form ${var} in its argument. Example:
.. btest-include:: ${var}/path/to/file
When you now run Sphinx, it will automatically generate a test
file in the directory specified by the btest_tests variable in
the Sphinx conf.py configuration file. In this example, the filename
would be include-path_to_file.btest (it automatically adds a prefix of
“include-” and a file extension of “.btest”). When you run
the tests externally, the tests generated by the btest-include
directive will check if any of the included content has changed (you’ll
first need to run btest -u to establish the initial baseline).
