BTest is a powerful framework for writing system tests. Freely borrowing some ideas from other packages, its 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 robustly compare output against a previously established baseline.
This document describes BTest 0.69-22. See the CHANGES
file in the source tree for version history.
BTest has the following prerequisites:
- Python version >= 3.5 (older version may work, but are not well-tested).
- 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 is simple and standard via pip
:
> pip install btest
Alternatively, you can download a tarball from PyPI and install locally:
> tar xzvf btest-*.tar.gz
> cd btest-*
> python3 setup.py install
The same approach also works on a local git clone of the source tree, located at https://github.com/zeek/btest.
Each 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).
A BTest testsuite consists of one or more "btests", executed by the btest
driver. Btests are plain text files in which btest
identifies keywords with corresponding arguments that tell it what to do. BTest is not a language; it recognizes keywords in any text file, including when embedded in other scripting languages. A common idiom in BTest is to use keywords to process the btest file via a particular command, often a script interpreter. This approach feels unusal at first, but lends BTest much of its flexibility: btest files can contain pretty much anything, as long as btest
identifies keywords in it.
btest
requires a configuration file. With it, you can run btest
on an existing testsuite in several ways:
Point it at directories containing btests:
> btest ./testsuite/
Use the config file to enumerate directories to scan for tests, via the
TestDirs
option:> btest
Run btests selectively, by pointing
btest
at a specific test file:> btest ./testsuite/my.test
More detail on this when we cover test selection.
In the most simple case, btest
simply executes a set of command lines, each of which must be prefixed with the @TEST-EXEC:
keyword:
> 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
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
executes (something similar to) sh examples/t3.sh
, and then checks the return value as usual. The example also shows that the @TEST-EXEC
keyword can appear anywhere, in particular inside the comment section of another language.
Now, let's say we want to verify the output of a program, making sure that it matches our expectations---a common use case for BTest. To do this, we rely on BTest's built-in support for test baselines. These baselines record prior output of a test, adding support for abstracting away brittle details such as ever-changing timestamps or home directories. BTest comes with tooling to establish, update, and verify baselines, and to plug in "canonifiers": scripts that abstract, or "normalize", troublesome detail from a baseline.
In our test, we first add a command line that produces the output we want to check, and then run btest-diff
to make sure it matches the previously recorded baseline. btest-diff
is itself just a script that returns success if the output matches a pre-recorded baseline after applying any required normalizations.
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. The btest
command includes a baseline-update mode, set via -U
, that achieves this:
> btest -U examples/t4.awk
btest-diff
recognizes this update mode via an environment variable set by btest
, and records the dots
file in a separate baseline folder. With this baseline in place, modifications to the output now trigger a test failure:
> 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 changed in dots
to trigger the failure, btest
allows us to record the discrepancies via a diagnostics mode that records them in a file called .diag
:
> 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, the test passes again:
> rm ~/.NEWDOTFILE
> btest -d examples/t4.awk
examples.t4 ... ok
That's the essence of the functionality the btest
package provides. This example did not use canonifiers. We cover these, and a number of additional options that extend or modify this basic approach, in the following sections.
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. Exit code 1 can also result in case of other errors.
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
ALTERNATIVE
is-
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 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.cfg
if found in the current directory. An alternative way to specify a different config file is with theBTEST_CFG
environment 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 thediff
between 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 ambiguous 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
:rst
prints reStructuredText, andmd
prints 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.sh
will 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.
- --trace-file=TRACEFILE
Record test execution timings in Chrome tracing format to the given file. If the file exists already, it is overwritten. The file can be loaded in Chrome-based browsers at about:tracing, or converted to standalone HTML with trace2html.
- -U, --update-baseline
Records a new baseline for all
btest-diff
commands found in any of the specified tests. To do this, all tests are run as normal except that whenbtest-diff
is 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-diff
command 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.
- -z RETRIES, --retries=RETRIES
Retry any failed tests up to this many times to determine if they are unstable.
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).
The following options can be set in the btest
section of the configuration file:
BaselineDir
One or more directories where to store the baseline files for
btest-diff
(note that the actual baseline files will be placed into test-specific subdirectories of this directory). By default, this is set to%(testbase)s/Baseline
.If multiple directories are to be used, they must be separated by colons.
btest-diff
will then search them for baseline files in order when looking for a baseline to compare against. When updating a baseline, it will always store the new version inside the first directory. Using multiple directories is most useful in combination with alternatives to support alternate executions where some tests produce expected differences in their output.This option can also be set through an environment variable
BTEST_BASELINE_DIR
.CommandPrefix
Changes the naming of all
btest
commands by replacing the@TEST-
prefix with a custom string. For example, withCommandPrefix=$TEST-
, the@TEST-EXEC
command becomes$TEST-EXEC
.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.
IgnoreDirs
A 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-ignore
in it.IgnoreFiles
A 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-IGNORE
in it.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.
MinVersion
On occasion, you'll want to ensure that the version of
btest
running your testsuite includes a particular feature. By setting this value to a given version number (as reported bybtest --version
),btest
installations older than this version will fail test execution with exit code 1 and a corresponding error message on stderr.PartFinalizer
An executable that will be executed each time a test part has successfully run. This operates similarly to
Finalizer
except that it runs after each test part rather than only at completion of the full test. See parts for more about test parts.PerfPath
Specifies a path to the
perf
tool, which is used on Linux to measure the execution times of tests. By default, BTest searches forperf
inPATH
.PortRange
Specifies a port range like "10000-11000" to use in conjunction with
@TEST-PORT
commands. Port assignments will be restricted to this range. The default range is "1024-65535".StateFile
The name of the state file to record the names of failing tests. Default is
.btest.failed.dat
.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.
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).
TmpDir
A directory where to create temporary files when running tests. By default, this is set to
%(testbase)s/.tmp
.
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.
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.
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 two specific environment variables---BTEST_TEST_BASE
and BTEST_BASELINE_DIR
---inside an alternative's environment section to have them not only be passed on to child processes, but also apply to the btest
process itself. That way, one can switch to a different base and baseline directories for an alternative.
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 $2
.
NOTE: There are a few limitations to the filter concept currently:
- Filters are always fed with
%INPUT
as their first argument. We should add a way to filter other files as well.- Filtered commands are only recognized if they are directly starting the command line. For example,
@TEST-EXEC: ls | cat >output
would not trigger the example filter above.- Filters are only executed for
@TEST-EXEC
, not for@TEST-EXEC-FAIL
.
Substitutions are similar to filters, yet they do not adapt the input but the command line being executed. A substitution is defined by adding a section [substitution-<name>]
to the configuration file. For each entry in this section, the entry's name specifies the command that is to be replaced with something else given as its value. Example:
[substitution-myalternative]
gcc=gcc -O2
Once the substitution is activated by running btest
with --alternative=myalternative
, every time a @TEST-EXEC
executes gcc
, that is replaced with gcc -O2
. The replacement is simple string substitution so it works not only with commands but anything found on the command line; it however only replaces full words, not subparts of words.
btest
scans a test file for lines containing keywords that trigger certain functionality. It knows the following keywords:
@TEST-ALTERNATIVE: <alternative>
Runs this test only for the given alternative (see alternative). If
<alternative>
isdefault
, the test executes when BTest runs with no alternative given (which however is the default anyway).@TEST-COPY-FILE: <file>
Copy the given file into the test's directory before the test is run. If
<file>
is a relative path, it's interpreted relative to the BTest's base directory. Environment variables in<file>
will be replaced if enclosed in${..}
. This command can be given multiple times.@TEST-DOC: <docstring>
Associates a documentation string with the test. These strings get included into the output of the
--documentation
option.
@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>
:%INPUT
will 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%DIR
will 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%INPUT
file 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_BASE
The BTest base directory, i.e., the directory where
btest.cfg
is located.TEST_BASELINE
A list of directories where the command can save permanent information across
btest
runs. (This is wherebtest-diff
stores its baseline inUPDATE
mode.)Multiple entries are separated by colons. If more than one entry is given, semantics should be to search them in order. (This is where
btest-diff
stores its baseline inUPDATE
mode.)TEST_DIAGNOSTICS
A file where further diagnostic information can be saved in case a command fails (this is also where
btest-diff
stores its diff). If this file exists, then the--diagnostics-all
or--diagnostics
options will show this file (for the latter option, only if a command fails).TEST_MODE
This is normally set to
TEST
, but will beUPDATE
ifbtest
is run with--update-baseline
, orUPDATE_INTERACTIVE
if run with--update-interactive
.TEST_NAME
The name of the currently executing test.
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-diff
uses 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-diff
uses this special exit code whenbtest
is run with the--update-interactive
option and the user chooses to abort the tests when prompted to record a new baseline.TEST_VERBOSE
The path of a file where the test can record further information about its execution that will be included with BTest's
--verbose
output. This is for further tracking the execution of commands and should generally generate output that follows a line-based structure.
@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-GROUP: <group>
Assigns the test to a group of name
<group>
. By using option-g
one can limit execution to all tests that belong to a given group (or a set of groups).@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
IgnoreFiles
option in the btest configuration file.@TEST-KNOWN-FAILURE
Marks 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.
@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-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 thePortRange
option. IPv6 is not supported. Note that using the-j
option 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 actually runs and claims it for itself.@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-SERIALIZE: <set>
When using option
-j
to parallelize execution, all tests that specify the same serialization set are guaranteed to run sequentially.<set>
is an arbitrary user-chosen string.@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-FILE
is found. The lines containing@TEST-START-FILE
and@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-START-NEXT
This keyword lets you define multiple test inputs in the same file, all executing with the same command lines. See defining multiple tests in one file for details.
Internally, btest
uses logical names for tests, abstracting input files. Those names result from substituting path separators with dots, ignoring btest file suffixes, and potentially adding additional labeling. btest
does this only for tests within the TestDirs
directories given in the configuration file.
In addition to the invocations covered in Running BTest, you can use logical names when telling btest
which tests to run. For example, instead of saying :
> btest testsuite/foo.sh
you can use:
> btest testsuite.foo
This distinction rarely matters, but it's something to be aware of when defining multiple tests in one file, which we cover next.
On occasion you want to use the same constellation of keywords on a set of input files. BTest supports this via the @TEST-START-NEXT
keyword. When btest
encounters this keyword, it initially considers the input file to end at that point, and runs all @TEST-EXEC-*
with an %INPUT
truncated accordingly. Afterwards, it creates a new %INPUT
with everything following the @TEST-START-NEXT
marker, running the same commands again. (It ignores any @TEST-EXEC-*
lines later in the file.)
The effect is that a single file can define multiple tests that the btest
output will enumerate:
> 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
[...]
btest
automatically generates the -<n>
suffix for each of the tests.
NOTE: It matters how you name tests when running them individually. When you specify the btest file ("
examples/t5.sh
"),btest
will run all of the contained tests. When you use the logical name,btest
will run only that specific test: in the above scenario,examples.t5
runs only the first test defined in the file, whileexamples.t5-2
only runs the second. This also applies to baseline updates.
One can also 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.
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. For examples of canonifier scripts, take a look at those used in the Zeek distribution.
NOTE:
btest-diff
passes both the pre-recorded baseline and the fresh test output through any canonifiers before comparing their contents. BTest version 0.63 introduced two changes inbtest-diff
's baseline handling:
btest-diff
now records baselines in canonicalized form. The benefit here is that by canonicalizing upon recording, you can usebtest -U
more freely, keeping expected noise out of revision control. The downside is that updates to canonifiers require a refresh of the baselines.btest-diff
now prefixes the baselines with a header that warns against manual modification, and knows to exclude that header from comparison. We recommend only ever updating baselines viabtest -U
(or its interactive sibling,-u
).Once you use canonicalized baselines in your project, it's a good idea to use
MinVersion = 0.63
in your btest.cfg to avoid the use of olderbtest
installations. Since these are unaware of the new baseline header and repeated application of canonifiers may cause unexpected alterations to already-canonified baselines, using such versions will likely cause test failures.
btest
baselines usually consist of text files, i.e. content that mostly makes sense to process line by line. It's possible to use binary data as well, though. For such data, btest-diff
supports a binary mode in which it will treat the baselines as binary "blobs". In this mode, it will compare test output to baselines for byte-by-byte equality only, it will never apply any canonifiers, and it will leave the test output untouched during baseline updates.
To use binary mode, invoke btest-diff
with the --binary
flag.
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.log
to access it.btest-bg-wait [-k] <timeout>
This script waits for all processes previously spawned via
btest-bg-run
to finish. If any of them exits with a non-zero return code,btest-bg-wait
does 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-k
is not given. If-k
is 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.
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.
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
.
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.
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
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
.
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_CMDLINE
in 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_CMD
before including. If-r
is given, it filters the file's content instead of stdout.- -n N
Include only
N
lines of output, adding a[...]
marker if there's more.- -o
Do not include the executed command into the generated documentation, just its output.
- -r FILE
Insert
FILE
into output instead of stdout. TheFILE
must be created by a previous@TEST-EXEC
or@TEST-COPY-FILE
.
btest-rst-include [options] <file>
Includes <file>
inside a code block. The <file>
must be created by a previous @TEST-EXEC
or @TEST-COPY-FILE
.
This script provides the following options:
- -n N
Include only
N
lines 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 leveragebtest-rst-cmd
internally.
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).
BTest is open-source under a BSD license.