Testing Guide

We can never have enough testing. Any additional tests you can write are always greatly appreciated.

Unit Tests

Implementing Tests

The UnifyFS Test Suite uses the Test Anything Protocol (TAP) and the Automake test harness. This test suite has two types of TAP tests (shell scripts and C) to allow for testing multiple aspects of UnifyFS.

Shell Script Tests

Test cases in shell scripts are implemented with sharness, which is included in the UnifyFS source distribution. See the file sharness.sh for all available test interfaces. UnifyFS-specific sharness code is implemented in scripts in the directory sharness.d. Scripts in sharness.d are primarily used to set environment variables and define convenience functions. All scripts in sharness.d are automatically included when your script sources sharness.sh.

The most common way to implement a test case with sharness is to use the test_expect_success() function. Your script must first set a test description and source the sharness library. After all tests are defined, your script should call test_done() to print a summary of the test run.

Test cases that demonstrate known breakage should use the sharness function test_expect_failure() to alert developers about the problem without causing the overall test suite to fail. Failing test cases should be tracked with github issues.

Here is an example of a sharness test:


test_description="My awesome test cases"

. $(dirname $0)/sharness.sh

test_expect_success "Verify some critical invariant" '
    test 1 -eq 1

test_expect_failure "Prove this someday" '
    test "P" == "NP"

# Various tests available to use inside test_expect_success/failure
test_expect_success "Show various available tests" '
    test_path_is_dir /somedir
    test_must_fail test_dir_is_empty /somedir
    test_path_is_file /somedir/somefile

# Use test_set_prereq/test_have_prereq to conditionally skip tests
[[ -n $(which h5cc 2>/dev/null) ]] && test_set_prereq HAVE_HDF5
if test_have_prereq HAVE_HDF5; then
    # run HDF5 tests

# Can also check for prereq in individual test
test_expect_success HAVE_HDF5 "Run HDF5 test" '
    # Run HDF5 test


C Program Tests

C programs use the libtap library to implement test cases. All available testing functions are viewable in the libtap README. Convenience functions common to test cases written in C are implemented in the library lib/testutil.c. If your C program needs to use environment variables set by sharness, it can be wrapped in a shell script that first sources sharness.d/00-test-env.sh and sharness.d/01-unifyfs-settings.sh. Your wrapper shouldn’t normally source sharness.sh itself because the TAP output from sharness might conflict with that from libtap.

The most common way to implement a test with libtap is to use the ok() function. TODO test cases that demonstrate known breakage are surrounded by the libtap library calls todo() and end_todo().

Here are some examples of libtap tests:

#include "t/lib/tap.h"
#include "t/lib/testutil.h"
#include <string.h>

int main(int argc, char *argv[])
    int result;

    result = (1 == 1);
    ok(result, "1 equals 1: %d", result);

    /* Or put a function call directly in test */
    ok(somefunc() == 42, "somefunc() returns 42");
    ok(somefunc() == -1, "somefunc() should fail");

    /* Use pass/fail for more complex code paths */
    int x = somefunc();
    if (x > 0) {
        pass("somefunc() returned a valid value");
    } else {
        fail("somefunc() returned an invalid value");

    /* Use is/isnt for string comparisions */
    char buf[64] = {0};
    ok(fread(buf, 12, 1, fd) == 1, "read 12 bytes into buf);
    is(buf, "hello world", "buf is \"hello world\"");

    /* Use cmp_mem to test first n bytes of memory */
    char* a = "foo";
    char* b = "bar";
    cmp_mem(a, b, 3);

    /* Use like/unlike to string match to a POSIX regex */
    like("stranger", "^s.(r).*\\1$", "matches the regex");

    /* Use dies_ok/lives_ok to test whether code causes an exit */
    dies_ok({int x = 0/0;}, "divide by zero crashes");

    /* Use todo for failing tests to be notified when they start passing */
    todo("Prove this someday");
    result = strcmp("P", "NP");
    ok(result == 0, "P equals NP: %d", result);

    /* Use skip/end_skip when a feature isn't implemented yet, or to
    conditionally skip when a resource isn't available */
    skip(TRUE, 2, "Reason for skipping tests");

        skip(TRUE, 2, "Don't have SOME_FEATURE");



Including the file and line number, as well as any useful variable values, in each test output can be very helpful when a test fails or needs to be debugged.

ok(somefunc() == 42, "%s:%d somefunc() returns 42", __FILE__,

Also, note that errno is only set when an error occurs and is never set back to 0 implicitly. When testing for a failure and using errno as part of the test, resetting errno after the test will prevent subsequent tests from appearing to error.

ok(somefunc() == -1 && errno == ENOTTY,
   "%s:%d somefunc() should fail (errno=%d): %s",
   __FILE__, __LINE__, errno, strerror(errno));
errno = 0;

Adding Tests

The UnifyFS Test Suite uses the Test Anything Protocol (TAP) and the Automake test harness. By convention, test scripts and programs that output TAP are named with a “.t” extension.

To add a new test case to the test harness, follow the existing examples in t/Makefile.am. In short, add your test program to the list of tests in the TESTS variable. If it is a shell script, also add it to check_SCRIPTS so that it gets included in the source distribution tarball.

Test Suites

If multiple tests fit within the same category (i.e., tests for creat and mkdir both fall under tests for sysio) then create a test suite to run those tests. This makes it so less duplication of files and code is needed in order to create additional tests.

To create a new test suite, look at how it is currently done for the sysio_suite in t/Makefile.am and t/sys/sysio_suite.c:

If you’re testing C code, you’ll need to use environment variables set by sharness.

  • Create a shell script, <####-suite-name>.t (the #### indicates the order in which they should be run by the tap-driver), that wraps your suite and sources sharness.d/00-test-env.sh and sharness.d/01-unifyfs-settings.sh
  • Add this file to t/Makefile.am in the TESTS and check_SCRIPTS variables and add the name of the file (but with a .t extension) this script runs to the libexec_PROGRAMS variable

You can then create the test suite file and any tests to be run in this suite.

  • Create a <test_suite_name>.c file (i.e., sysio_suite.c) that will contain the main function and mpi job that drives your suite
    • Mount unifyfs from this file
    • Call testing functions that contain the test cases (created in other files) in the order desired for testing, passing the mount point to those functions
  • Create a <test_suite_name>.h file that declares the names of all the test functions to be run by this suite and include this in the <test_suite_name>.c file
  • Create <test_name>.c files (i.e., open.c) that contains the testing function (i.e., open_test(char* unifyfs_root)) that houses the variables and libtap tests needed to test that individual function
    • Add the function name to the <test_suite_name>.h file
    • Call the function from the <test_suite_name>.c file

The source files and flags for the test suite are then added to the bottom of t/Makefile.am.

  • Add the <test_suite_name>.c and <test_suite_name>.h files to the <test_suite>_SOURCES variable
  • Add additional <test_name>.c files to the <test_suite>_SOURCES variable as they are created
  • Add the associated flags for the test suite (if the suite is for testing wrappers, add a suite and flags for both a gotcha and a static build)

Test Cases

For testing C code, test cases are written using the libtap library. See the C Program Tests section above on how to write these tests.

To add new test cases to any existing suite of tests:

  1. Simply add the desired tests (order matters) to the appropriate <test_name>.c file

If the test cases needing to be written don’t already have a file they belong in (i.e., testing a wrapper that doesn’t have any tests yet):

  1. Creata a <function_name>.c file with a function called <function_name>_test(char* unifyfs_root) that contains the desired libtap test cases
  2. Add the <function_name>_test to the corresponding <test_suite_name>.h file
  3. Add the <function_name>.c file to the bottom of t/Makefile.am under the appropriate <test_suite>_SOURCES variable(s)
  4. The <function_name>_test function can now be called from the <test_suite_name>.c file

Running the Tests

To manually run the UnifyFS test suite, simply run make check from your build/t directory. If changes are made to existing files in the test suite, the tests can be run again by simply doing make clean followed by make check. Individual tests may be run by hand. The test 0001-setup.t should normally be run first to start the UnifyFS daemon.


If you are using Spack to install UnifyFS then there are two ways to manually run these tests:

  1. Upon your installation with Spack

    spack install -v --test=root unifyfs

  2. Manually from Spack’s build directory

    spack install --keep-stage unifyfs

    spack cd unifyfs

    cd spack-build/t

    make check

The tests in https://github.com/LLNL/UnifyFS/tree/dev/t are run automatically by Travis CI along with the style checks when a pull request is created or updated. All pull requests must pass these tests before they will be accepted.

Interpreting the Results

After a test runs, its result is printed out consisting of its status followed by its description and potentially a TODO/SKIP message. Once all the tests have completed (either from being run manually or by Travis CI), the overall results are printed out, as shown in the image on the right.

There are six possibilities for the status of each test: PASS, FAIL, XFAIL, XPASS, SKIP, and ERROR.

The test had the desired result.

The test did not have the desired result. These must be fixed before any code changes can be accepted.

If a FAIL occurred after code had been added/changed then most likely a bug was introduced that caused the test to fail. Some tests may fail as a result of earlier tests failing. Fix bugs that are causing earlier tests to fail first as, once they start passing, subsequent tests are likely to start passing again as well.


The test was expected to fail, and it did fail.

An XFAIL is created by surrounding a test with todo() and end_todo. These are tests that have identified a bug that was already in the code, but the cause of the bug hasn’t been found/resolved yet. An optional message can be passed to the todo("message") call which will be printed after the test has run. Use this to explain how the test should behave or any thoughts on why it might be failing. An XFAIL is not meant to be used to make a failing test start “passing” if a bug was introduced by code changes.


A test passed that was expected to fail. These must be fixed before any code changes can be accepted.

The relationship of an XPASS to an XFAIL is the same as that of a FAIL to a PASS. An XPASS will typically occur when a bug causing an XFAIL has been fixed and the test has started passing. If this is the case, remove the surrounding todo() and end_todo from the failing test.


The test was skipped.

Tests are skipped because what they are testing hasn’t been implemented yet, or they apply to a feature/variant that wasn’t included in the build (i.e., HDF5). A SKIP is created by surrounding the test(s) with skip(test, n, message) and end_skip where the test is what determines if these tests should be skipped and n is the number of subsequent tests to skip. Remove these if it is no longer desired for those tests to be skipped.


A test or test suite exited with a non-zero status.

When a test fails, the containing test suite will exit with a non-zero status, causing an ERROR. Fixing any test failures should resolve the ERROR.

Running the Examples

To run any of these examples manually, refer to the Examples documentation.

The UnifyFS examples are also being used as integration tests with continuation integration tools such as Bamboo or GitLab.

Integration Tests

The UnifyFS examples are being used as integration tests with continuation integration tools such as Bamboo or GitLab.

To run any of these examples manually, refer to the Examples documentation.

Running the Tests


UnifyFS’s integration test suite requires MPI and currently only supports srun and jsrun MPI launch commands. Changes are coming to support mpirun.

UnifyFS’s integration tests are primarly set up to be run all as one suite. However, they can be run individually if desired.

The testing scripts in t/ci depend on sharness, which is set up in the containing t/ directory. These tests will not function properly if moved or if they cannot find the sharness files.


Whether running all tests or individual tests, first make sure you have either interactively allocated nodes or are submitting a batch job to run them.

Also make sure all dependencies are installed and loaded.

By default, the integration tests will use the number of processes-per-node as there are nodes allocated for the job (i.e., if 4 nodes were allocated, then 4 processes will be run per node). This can be changed by setting the $CI_NPROCS environment variable.


In order to run the the integration tests from a Spack installation of UnifyFS, you’ll need to tell Spack to use a different location for staging builds in order to have the source files available from inside an allocation.

Open your Spack config file

spack config edit config

and provide a path that is visible during job allocations:

  - /visible/path/from/all/allocated/nodes
  # or build directly inside Spack's install directory
  - $spack/var/spack/stage

Then make sure to include the --keep-stage option when installing:

spack install --keep-stage unifyfs

Running All Tests

To run all of the tests, simply run ./RUN_CI_TESTS.sh.



$ prove -v RUN_CI_TESTS.sh

Running Individual Tests

In order to run individual tests, testing functions and variables need to be set up first, and the UnifyFS server needs to be started. To do this, first source the t/ci/001-setup.sh script followed by 002-start-server.sh. Then source each desired test script after that preceded by $CI_DIR/. When finished, source the 990-stop-server.sh script last to stop the server and clean up.

$ . full/path/to/001-setup.sh
$ . $CI_DIR/002-start-server.sh
$ . $CI_DIR/100-writeread-tests.sh
$ . $CI_DIR/990-stop-server.sh

Configuration Variables

Along with the already provided UnifyFS Configuration options/environment variables, there are available environment variables used by the integration testing suite that can be set in order to change the default behavior. They are listed below in the order they are set up.


USAGE: CI_PROJDIR=/base/location/to/search/for/UnifyFS/source/files

During setup, the integration tests will search for the unifyfsd executable and installed example scripts if the UnifyFS install directory is not provided by the user with the UNIFYFS_INSTALL envar. CI_PROJDIR is the base location where this search will start and defaults to CI_PROJDIR=$HOME.


USAGE: UNIFYFS_INSTALL=/path/to/dir/containing/UnifyFS/bin/directory

The full path to the directory containing the bin/ and libexec/ directories for a UnifyFS installation. Set this envar to prevent the integration tests from searching for a UnifyFS install directory automatically.


USAGE: CI_NPROCS=<number-of-process-per-node>

The number of processes to use per node inside a job allocation. This defaults to the number of processes per node as there are nodes in the allocation (i.e., if 4 nodes were allocated, then 4 processes will be run per node). This should be adjusted if fewer processes are desired on multiple nodes, multiple processes are desired on a single node, or a large number of nodes have been allocated.



In the event $UNIFYFS_LOG_DIR has not been set, the logs will be put in $SHARNESS_TRASH_DIRECTORY, as set up by sharness.sh, and cleaned up automatically after the tests have run. The logs will be in a <system-name>_<jobid>/ subdirectory. Should any tests fail, the trash directory will not be cleaned up for debugging purposes. Setting CI_LOG_CLEANUP=no|NO will move the <system-name>_<jobid>/ logs directory to $CI_DIR (the directory containing the integration tests) to allow them to persist even when all tests pass. This envar defauls to yes.


Setting $UNIFYFS_LOG_DIR will put all created logs in the designated path and will not clean them up.



After all tests have run, the nodes on which the tests were ran will automatically be cleaned up. This cleanup includes ensuring unifyfsd has stopped and deleting any files created by UnifyFS or its dependencies. Set CI_HOST_CLEANUP=no|NO to skip cleaning up. This envar defaults to yes.


PDSH is required for cleanup and cleaning up is simply skipped if not found.



Setting this to no|NO sets both $CI_LOG_CLEANUP and $CI_HOST_CLEANUP to no|NO.


USAGE: CI_TEMP_DIR=/path/for/temporary/files/created/by/UnifyFS

Can be used as a shortcut to set UNIFYFS_RUNSTATE_DIR and UNIFYFS_META_DB_PATH to the same path. This envar defaults to CI_TEMP_DIR=${TMPDIR}/unifyfs.${USER}.${JOB_ID}.



Determines whether any <example-name>-posix tests should be run since they require a real mountpoint to exist.

This envar defaults to yes. However, when $UNIFYFS_MOUNTPOINT is set to a real directory, this envar is switched to no. The idea behind this is that the tests can be run a first time with a fake mountpoint (which will also run the posix tests), and then the tests can be run again with a real mountpoint and the posix tests wont be run twice. This behavior can be overridden by setting CI_TEST_POSIX=yes|YES before running the integration tests when $UNIFYFS_MOUNTPOINT is set to an existing directory.

An example of testing a posix example can be see below.


The the posix mountpoint envar, CI_POSIX_MP, is set up inside $SHARNESS_TRASH_DIRECTORY automatically and cleaned up afterwards. However, this envar can be set before running the integration tests as well. If setting this, ensure that it is a shared file system that all allocated nodes can see.

Adding New Tests

In order to add additional tests, create a script after the fashion of t/ci/100-writeread-tests.sh where the prefixed number indicates the desired order for running the tests. Then source that script in t/ci/RUN_CI_TESTS.sh in the desired order.

Just like the helpers functions found in sharness.d, there are continuous integration helper functions (see below for more details) available in t/ci/ci-functions.sh. These exist to help make adding new tests as simple as possible.

One particularly useful function is unify_run_test(). Currently, this function is set up to work for the write, read, writeread, and checkpoint-restart examples. This function sets up the MPI job run command and default arguments as well as any default arguments wanted by all examples. See below for details.

Example Helper Functions

There are helper functions available in t/ci/ci-functions.sh that can make running and testing the examples much easier. These may get adjusted over time to accommodate other examples, or additional functions may need to be written. Some of the main helper functions that might be useful for running examples are:


USAGE: unify_run_test app_name "app_args" [output_variable_name]

Given a example application name and application args, this function runs the example with the appropriate MPI runner and args. This function is meant to make running the cr, write, read, and writeread examples as easy as possible.

The build_test_command() function is called by this function which automatically sets any options that are always wanted (-vkf as well as -U and the appropriate -m if posix test or not). The stderr output file is also created (based on the filename that is autogenerated) and the appropriate option is set for the MPI job run command.

Args that can be passed in are ([-pncbx][-A|-M|-P|-S|-V]). All other args (see Running the Examples) are set automatically, including the filename (which is generated based on the input $app_name and $app_args).

The third parameter is an optional “pass-by-reference” parameter that can contain the variable name for the resulting output to be stored in, allowing this function to be used in one of two ways:

Using command substitution
app_output=$(unify_run_test $app_name "$app_args")


Using a “pass-by-reference” variable
unifyfs_run_test $app_name "$app_args" app_output

This function returns the return code of the executed example as well as the output produced by running the example.


If unify_run_test() is simply called with only two arguments and without using command substitution, the resulting output will be sent to the standard output.

The results can then be tested with sharness:


app_args="-p n1 -n32 -c $((16 * $KB)) -b $MB

unify_run_test $app_name "$app_args" app_output
line_count=$(echo "$app_output" | wc -l)

test_expect_success "$app_name $app_args: (line_count=$line_count, rc=$rc)" '
    test $rc = 0 &&
    test $line_count = 8

USAGE: get_filename app_name app_args [app_suffix]

Builds and returns the filename for an example so that if it shows up in the $UNIFYFS_MOUNTPOINT (when using an existing mountpoint), it can be tracked to its originating test for debugging. Error files are created with this filename and a .err suffix and placed in the logs directory for debugging.

Also allows testers to get what the filename will be in advance if called from a test suite. This can be used for posix tests to ensure the file showed up in the mount point, as well as for cp/stat tests that potentially need the filename from a previous test.

Note that the filename created by unify_run_test() will have a .app suffix.

Returns a string with the spaces removed and hyphens replaced by underscores.

get_filename write-static "-p n1 -n 32 -c 1024 -b 1048576" ".app"

Some uses cases may be:

  • posix tests where the file existence is checked for after a test was run
  • cp/stat tests where an already existing filename from a prior test is needed

For example:


app_args="-p nn -n32 -c $((16 * $KB)) -b $MB

unify_run_test $app_name "$app_args" app_output
line_count=$(echo "$app_output" | wc -l)
filename=$(get_filename $app_name "$app_args" ".app")

test_expect_success POSIX "$app_name $app_args: (line_count=$line_count, rc=$rc)" '
    test $rc = 0 &&
    test $line_count = 8 &&
    test_path_has_file_per_process $CI_POSIX_MP $filename

Sharness Helper Functions

There are also additional sharness functions for testing the examples available when t/ci/ci-functions.sh is sourced. These are to be used with sharness for testing the results of running the examples with or without using the Example Helper Functions.


USAGE: process_is_running process_name seconds_before_giving_up

Checks if a process with the given name is running on every host, retrying up to a given number of seconds before giving up. This function overrides the process_is_running() function used by the UnifyFS unit tests. The primary difference being that this function checks for the process on every host.

Expects two arguments:

  • $1 - Name of a process to check for
  • $2 - Number of seconds to wait before giving up

USAGE: process_is_not_running process_name seconds_before_giving_up

Checks if a process with the given name is not running on every host, retrying up to a given number of seconds before giving up. This function overrides the process_is_not_running() function used by the UnifyFS unit tests. The primary difference being that this function checks that the process is not running on every host.

Expects two arguments:

  • $1 - Name of a process to check for
  • $2 - Number of seconds to wait before giving up
test_expect_success "unifyfsd is not running" '
    process_is_not_running unifyfsd 5

USAGE: test_path_is_dir dir_name [optional]

Checks that a directory with the given name exists and is accessible from each host. Does NOT need to be a shared directory. This function overrides the test_path_is_dir() function in sharness.sh, the primary difference being that this function checks for the dir on every host in the allocation.

Takes once argument with an optional second:

  • $1 - Path of the directory to check for
  • $2 - Can be given to provide a more precise diagnosis
test_expect_success "$dir_name is an existing directory" '
    test_path_is_dir $dir_name

USAGE: test_path_is_shared_dir dir_name [optional]

Check if same directory (actual directory, not just name) exists and is accessible from each host.

Takes once argument with an optional second:

  • $1 - Path of the directory to check for
  • $2 - Can be given to provide a more precise diagnosis
test_expect_success "$dir_name is a shared directory" '
    test_path_is_shared_dir $dir_name

USAGE: test_path_has_file_per_process dir_path file_name [optional]

Check if the provided directory path contains a file-per-process of the provided file name. Assumes the directory is a shared directory.

Takes two arguments with an optional third:

  • $1 - Path of the shared directory to check for the files
  • $2 - File name without the appended process number
  • $3 - Can be given to provided a more precise diagnosis
test_expect_success "$dir_name has file-per-process of $file_name" '
    test_path_has_file_per_process $dir_name $file_name

There are other helper functions available as well, most of which are being used by the test suite itself. Details on these functions can be found in their comments in t/ci/ci-functions.sh.