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.
Contents
- Prerequisites
- Download and Installation
- Running BTest
- Writing a Test
- Reference
- Selecting Tests
- Defining Multiple Tests in one File
- Splitting Tests into Parts
- Canonifying Diffs
- Binary Data in Baselines
- Running Processes in the Background
- Displaying Progress
- Timing Execution
- Integration with Sphinx
- License
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
TestDirsoption:> btest
Run btests selectively, by pointing
btestat 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 the BTEST_CFG environment
variable (however, the command-line option overrides BTEST_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 the
diff 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, and md 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
for example/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 when btest-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:
BaselineDirOne 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-diffwill 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
btestcommands by replacing the@TEST-prefix with a custom string. For example, withCommandPrefix=$TEST-, the@TEST-EXECcommand 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.
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.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
btestrunning your testsuite includes a particular feature. By setting this value to a given version number (as reported bybtest --version),btestinstallations 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
Finalizerexcept 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
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 conjunction with
@TEST-PORTcommands. 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 $2.
NOTE: There are a few limitations to the filter concept currently:
- Filters are always fed with
%INPUTas their first argument. We should add a way to filter other files as well.- Filtered commands are only recognized if they are directly starting the command line. For example,
@TEST-EXEC: ls | cat >outputwould not trigger the example filter above.- Filters are only executed for
@TEST-EXEC, not for@TEST-EXEC-FAIL.
Substitutions are similar to filters, yet they do not adapt the input
but the command line being executed. A substitution is defined by
adding a section [substitution-<name>] to the configuration file.
For each entry in this section, the entry's name specifies the
command that is to be replaced with something else given as its value.
Example:
[substitution-myalternative] gcc=gcc -O2
Once the substitution is activated by running btest with
--alternative=myalternative, every time a @TEST-EXEC executes
gcc, that is replaced with gcc -O2. The replacement is simple
string substitution so it works not only with commands but anything
found on the command line; it however only replaces full words, not
subparts of words.
btest scans a test file for lines containing keywords that
trigger certain functionality. It knows the following keywords:
@TEST-ALTERNATIVE: <alternative>- Runs this test only for the given alternative (see alternative).
If
<alternative>isdefault, the test executes when BTest runs with no alternative given (which however is the default anyway). @TEST-COPY-FILE: <file>- Copy the given file into the test's directory before the test is
run. If
<file>is a relative path, it's interpreted relative to the BTest's base directory. Environment variables in<file>will be replaced if enclosed in${..}. 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
--documentationoption.
@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_BASE- The BTest base directory, i.e., the directory where
btest.cfgis located. TEST_BASELINEA list of directories where the command can save permanent information across
btestruns. (This is wherebtest-diffstores its baseline inUPDATEmode.)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-diffstores its baseline inUPDATEmode.)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_NAME- The name of the currently executing test.
TEST_PARTThe 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 whenbtestis run with the--update-interactiveoption 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
--verboseoutput. 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-gone 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
IgnoreFilesoption in the btest configuration file. @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.
@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 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 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
-jto 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-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 =============================== 3Multiple 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"),btestwill run all of the contained tests. When you use the logical name,btestwill run only that specific test: in the above scenario,examples.t5runs only the first test defined in the file, whileexamples.t5-2only 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-diffpasses 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-diffnow records baselines in canonicalized form. The benefit here is that by canonicalizing upon recording, you can usebtest -Umore freely, keeping expected noise out of revision control. The downside is that updates to canonifiers require a refresh of the baselines.btest-diffnow 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 = 0.63in your btest.cfg to avoid the use of olderbtestinstallations. 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.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.
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. The FILE 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-cmdcan 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-cmdinternally.
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.