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

• BTest - A Simple Driver for Basic Unit Tests
  • Download
  • Prerequisites
  • Installation
  • Writing a Simple Test
  • Reference
    • Command Line Usage
    • Configuration
      • Options
      • Environment Variables
      • Alternatives
        • Environment Variables
        • Filters
        • Substitutions
    • Writing Tests
  • Splitting Tests into Parts
  • Canonifying Diffs
  • Running Processes in the Background
  • Displaying Progress
  • Timing Execution
  • Integration with Sphinx
    • Configuration
    • Including a Test into a Sphinx Document
    • Scripts
    • Including Literal Text
  • License

Download

You can find the latest BTest release for download at http://www.bro.org/download.

BTest’s git repository is located at git://git.bro.org/btest.git. You can browse the repository here.

This document describes BTest 0.57. 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 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.
-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 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: 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.
-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.

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.

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.

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 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.

CommandPrefix

Changes the naming of all btest commands by replacing the @TEST- prefix with a custom string. For example, with CommandPrefix=$TEST-, the @TEST-EXEC command 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 perf tool, which is used on Linux to measure the execution times of tests. By default, BTest searches for perf in PATH.

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 %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 >outout would 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>: %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_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 be UPDATE if btest is run with --update-baseline, or UPDATE_INTERACTIVE if run with --update-interactive.

TEST_BASELINE

The name of a directory where the command can save permanent information across btest runs. (This is where btest-diff stores its baseline in UPDATE mode.)

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 --verbose output. 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.cfg is 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-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 when btest is run with the --update-interactive option 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> is default, 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> is default, 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-NEXT

This is a short-cut for defining multiple test inputs in the same file, all executing with the same command lines. When @TEST-START-NEXT is encountered, the test file is initially considered to end at that point, and all @TEST-EXEC-* are run with an %INPUT truncated accordingly. Afterwards, a new %INPUT is created with everything following the @TEST-START-NEXT marker, 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 the btest output 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-NEXT can 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-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-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-DOC <docstring>

Associates a documentation string with the test. These strings get included into the output of the --documentation option.

@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-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-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.

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 using cmdline & 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 with btest-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.

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_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.
-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.
-n N	Include only N lines 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-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 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).

License

btest is open-source under a BSD licence.