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Document how to get the srcdir value in a c test program.

[[!meta title="Creating atf-based tests for NetBSD src"]]
[[!toc ]]

This quick tutorial provides a guideline on how to start creating new test
programs and/or test cases, how these tests are tied to the NetBSD source tree
and includes a short reference of the most commonly used functions.

You should start by reading the
[tests(7)]( manual
page, which provides a user-level overview on how to run the tests included in
NetBSD.  While reading this tutorial, you may also want to refer to these pages
on a need-to-know basis:

**IMPORTANT: Do not take anything for granted, SPECIALLY if you have previously
worked with and/or have seen src/regress/.  Your assumptions are most likely

# Test programs vs. test cases

So, what is what and how do you organize your tests?

A **test case** is a piece of code that exercises a particular functionality of
another piece of code.  Commonly, test cases validate the outcome of a
particular source function or class method, the validity of the execution of a
command with a particular combination of flags/arguments, etc.  Test cases are
supposed to be very concise, in the sense that they should just be testing *one

A **test program** is a binary that collects and exposes a group of test cases.
Typically, these test programs expose conceptually-related tests or all the
tests for a particular source file.

In general, having many test programs with **just one test case** in them is
**wrong** and smells from the previous layout of src/regress/.  Think about some
other organization.  And don't blame atf for this separation: this is extremely
common in (almost?) all other test frameworks and, when used wisely, becomes an
invaluable classification.

For example, suppose you have the following fictitious source files for the ls

* bin/ls/fs.c: Provides the list_files() and stat_files() functions.

* bin/ls/ui.c: Provides the format_columns() function.

* bin/ls/main.c: The main method for ls.

Then, you could define the following test programs and test cases:

* bin/ls/fs_test.c: Provides test cases for list_files and stat_files.  These
  would be named list_files__empty_directory, list_files__one_file,
  list_files__multiple_files, stat_files__directory, stat_files__symlink, etc.

* bin/ls/ui_test.c: Provides test cases for the format_columns function.  These
  would be named format_columns__no_files, format_columns__multiple_files, etc.

* bin/ls/ Provides "black box" test cases for the binary
  itself.  These would be named lflag, lflag_and_Fflag, no_flags, no_files, etc.

Try to keep your test case names as descriptive as possible so that they do not
require comments to explain what they intend to test.

# Test case parts

A test case is composed by three parts: the *head*, the *body* and the
*cleanup*.  Only the body is required; the other two routines are optional, but
you are strongly encouraged to provide the *head*, if only to describe the
purpose of your tests by setting the *descr* property.

## The head

The *head* is used **for the sole purpose** to define meta-data properties for
the test case.  (Eventually, this would not be specified programmatically, but
is how we deal with the information right now.)

The following properties are commonly useful:

* descr: A textual description of the purpose of the test case.

* require.user: Set to 'root' to tell the atf runtime that this test requires
  root privileges.  The test will later be skipped if you are running atf as
  non-root, and the test will be executed otherwise.

* use.fs: Set to 'true' if the test case creates temporary files in the "current
  directory".  If set to false, the atf runtime will set the "current directory"
  to an unwritable directory, which will disallow the creation of the temporary
  files and will make your test misteriously fail.

## The body

The *body* is the actual meat of the test case.  This is just a regular function
that executes any code you want and calls special atf functions to report
failures; see below.

In particular, be aware that the atf run-time **isolates** the execution of
every test case to prevent side-effects (such as temporary file leftovers,
in-memory data corruption, etc.).  In particular:

* A test case is **always executed as a subprocess** that is separate from the
  head and the cleanup.  This implies that you cannot pass any in-memory state
  between the three parts.  The only exception is that the body and the cleanup
  share the same temporary directory, so you can use the file system to pass
  information between them.

* The current working directory of a test case is changed to a temporary
  location that gets cleaned up later on automatically.  (Set the use.fs
  property to true in the head if you need to write to this temporary

* The environment of the test case is "sanitized" to get rid of variables that
  can cause side-effects; e.g. LC_ALL, TZ, etc.

# Running the test programs


    $ cd /usr/tests/
    $ atf-run | atf-report


Test programs get installed into the /usr/tests/ hierarchy.  The main reason for
doing that is to allow *any* user to test his system and to be able to convince
himself that everything is working correctly.

Imagine that you install NetBSD-current on a public-facing machine that has some
particular hardware only supported in the bleeding-edge source tree.  In this
scenario, you, as the administrator, could just go into /usr/tests/, run the
tests and know immediately if everything is working correctly in your
software+hardware combination or not.  No need to rely on promises from the
vendor, no need to deal with a source tree, no need to have a compiler

So, that's the theory.  Now, how does this map to our source tree?

At the moment, the source test programs are located somewhere under src/tests/.
Say, for example, that you have the src/tests/bin/ls/ui_test.c source file.
This Makefile in src/tests/bin/ls/ will take this source file and generate a
ui_test binary.  The Makefile will also generate an Atffile.  Both files (the
ui_test binary and the Atffile) will later be installed to /usr/tests/bin/ls/

## Executing a single test

In general, you **do not want to run a test program by hand**.  If you do so,
you do not take advantage of any of the isolation provided by the atf runtime.
This means that the test program will probably leave some temporary files behind
or will raise some false negatives.

To run a test, use atf-run.  In general:

    $ atf-run | atf-report  # To run all the test programs in a directory.
    $ atf-run some_test | atf-report  # To run only the some_test program.

The only "legitimate" case in which you should be running test cases by hand is
to debug them:

    $ gdb --args ./some_test the_broken_test_case

... but be sure to clean up any leftover files if you do that.

## Executing tests during development

When you are in a subdirectory of src/tests/, you can generally run "make test"
to execute the tests of that particular subdirectory.  This assumes that the
tests have been installed into the destdir.

Please note that this is only provided for convenience but it is completely
unsupported.  Tests run this way may fail misteriously, and that is perfectly
fine as long as they work from their canonical locations in /usr/tests.

# Adding a new test

To add a new *test case* to the source tree, look for any test program in
src/tests/ that can assimilate it.  If you find such a program, just add the
test case to it: no other changes are required so your life is easy.  Otherwise,
you will have to create a new test program.

To add a new *test program* to the source tree:

1. Locate the appropriate subdirectory in which to put your test program.  It is
OK (and **expected**) to have multiple test programs into the same directory.
**Restrain yourself from creating one directory per test program.**

If the subdirectory exists:

1. Choose a sane name for the test program; the name must not be so specific
   that it restricts the addition of future test cases into it.

1. Create the test program source file using one of the templates below.
   E.g. src/tests/tutorial/sample_test.c.

1. Add the new test program to the Makefile.

If the subdirectory does not exist:

1. Do the same as above.

1. Create the Makefile for the directory using the templates below.

1. Edit the parent Makefile to recurse into the new subdirectory.

1. Edit src/etc/mtree/NetBSD.base.dist to register the new subdirectory.  Your
   test will be installed under /usr/tests/.

1. Edit src/distrib/sets/lists/tests/mi to register the new test program.  Do
   not forget to add .debug entries if your test program is a C/C++ binary.

## Makefile template

Follow this template to create your Makefile:

    .include <>

    # This must always be defined.

    # These correspond to the test programs you have in the directory.
    TESTS_C+= c1_test c2_test  # Correspond to c1_test.c and c2_test.c.
    TESTS_SH+= sh1_test sh2_test  # Correspond to sh1_test.c and sh2_test.c

    # Define only if your tests need any data files.
    FILES= testdata1.txt testdata2.bin  # Any necessary data files.

    .include <>

## Atffile template

*Atffiles are automatically generated by, so in general you will not
have to deal with them.*

What is an Atffile?  An Atffile is the atf-run counterpart of a "Makefile".
Given that atf tests *do not rely on a toolchain*, they cannot use make(1) to
script their execution as the old tests in src/regress/ did.

The Atffiles, in general, just provide a list of test programs in a particular
directory and the list of the subdirectories to descend into.

If you have to provide an Atffile explicitly because the automatic generation
does not suit your needs, follow this format:

    Content-Type: application/X-atf-atffile; version="1"

    prop: test-suite = NetBSD

    tp: first_test
    tp: second_test
    tp-glob: optional_*_test
    tp: subdir1
    tp: subdir2

# C test programs

## Template

The following code snippet provides a C test program with two test cases.  The
specific details as to how this works follow later:

    #include <atf-c.h>

    ATF_TC(tc, my_test_case);
    ATF_TC_HEAD(tc, my_test_case)
        atf_tc_set_md_var(tc, "descr", "This test case ensures that...");
    ATF_TC_BODY(tc, my_test_case)
        ATF_CHECK(true); /* Success; continue execution. */
        ATF_CHECK(false); /* Failure; continue execution. */

        ATF_CHECK_EQ(5, 2 + 2); /* Failure; continue execution. */
        ATF_REQUIRE_EQ(5, 2 + 2); /* Failure; abort execution. */

        if (!condition)
            atf_tc_fail("Condition not met!"); /* Abort execution. */

    ATF_TC_WITHOUT_HEAD(tc, another_test_case);
    ATF_TC_BODY(tc, another_test_case)
        /* Do more tests here... */

        ATF_TP_ADD_TC(tp, my_test_case);
        ATF_TP_ADD_TC(tp, another_test_case);

This program needs to be built with the Makefile shown below.  Once built, the
program automatically gains a main() method that provides a consistent user
interface to all test programs.  You are simply not inteded to provide your own
main method, nor to deal with the command-line of the invocation.

## How to build

To build a C test program, append the name of the test program (without the .c
extension) to the TESTS_C variable in the Makefile.

For example:

    .include <>


    TESTS_C+= fs_test ui_test

    .include <>

## Common functions

The following functions are commonly used from within a test case body:

* ATF_CHECK(boolean_expression): Checks if the given boolean expression is true
  and, if not, records a failure for the test case but *execution continues*.
  Using ATF_REQUIRE aborts execution immediately after a failure.

* ATF_CHECK_EQ(expected_expression, actual_expression): Checks if the two
  expressions match and, if not, records a failure.  Similarly, ATF_REQUIRE_EQ
  aborts immediately if the check fails.

* ATF_CHECK_STREQ(expected_string, actual_string): Same as ATF_CHECK_EQ but
  performs string comparisons with strcmp.

* atf_tc_skip(const char *format, ...): Marks the test case as skipped with the
  provided reason and exits.

* atf_tc_fail(const char *format, ...): Marks the test case as failed with the
  provided reason and exits.

* atf_tc_pass(void): Explicitly marks the test case as passed.  This is
  *implied* when the test case function ends, so you should not use this in

* atf_expect_fail(const char *format, ...): Tells the atf runtime that the code
  following this call is expected to raise one or more failures (be it with
  atf_tc_fail, ATF_CHECK_*, etc.).  Use this to mark a block of code that is
  known to be broken (e.g. a test that reproduces a known bug).  Use the string
  parameter to provide an explanation about why the code is broken; if possible,
  provide a PR number.  Lastly, to terminate the "expected failure" code block
  and reset the runtime to the default functionality, use the atf_expect_pass()

* atf_expect_death(const char *format, ...): Same as atf_expect_fail but expects
  an abrupt termination of the test case, be it due to a call to exit() or to
  the reception of a signal.

* atf_expect_exit(int exitcode, const char *fomat, ...): Same as atf_expect_fail
  but expects the test case to exit with a specific exitcode.  Provide -1 to
  indicate any exit code.

* atf_expect_signal(int signo, const char *fomat, ...): Same as atf_expect_fail
  but expects the test case to receive a specific signal.  Provide -1 to
  indicate any signal.

* atf_expect_timeout(const char *reason, ...): Same as atf_expect_fail but
  expects the test case to get stuck and time out.

* atf_tc_get_config_var("srcdir"): Returns the path to the directory containing
  the test program binary.  This must be used to locate any data/auxiliary files
  stored alongside the binary.

# Shell test programs

## Template

The following code snippet provides a shell test program with two test cases.
The details on how this works are provided later:

    atf_test_case my_test_case
    my_test_case_head() {
        atf_set "descr" "This test case ensures that..."
    my_test_case_body() {
        touch file1 file2

        cat >expout <<EOF
        # The following call validates that the 'ls' command returns an
        # exit code of 0, that its stdout matches exactly the contents
        # previously stored in the 'expout' file and that its stderr is
        # completely empty.  See atf-check(1) for details, which is the
        # auxiliary tool invoked by the atf_check wrapper function.
        atf_check -s eq:0 -o file:expout -e empty 'ls'

        atf_check_equal 4 $((2 + 2))

        if [ 'a' != 'b' ]; then
            atf_fail "Condition not met!"  # Explicit failure.

    atf_test_case another_test_case
    another_test_case_body() {
        # Do more tests...

    atf_init_test_cases() {
        atf_add_test_case my_test_case
        atf_add_test_case another_test_case

This program needs to be built with the Makefile shown below.  The program
automatically gains an entry point that provides a consistent user interface to
all test programs.  You are simply not inteded to provide your own "main
method", nor to deal with the command-line of the invocation.

## How to build

To build a shell test program, append the name of the test program (without the
.sh extension) to the TESTS_SH variable in the Makefile.

For example:

    .include <>


    TESTS_SH+= integration_test something_else_test

    .include <>

If you want to run the test program yourself, you should know that shell-based
test programs are processed with the atf-sh interpreter.  atf-sh is just a thin
wrapper over /bin/sh that loads the shared atf code and then delegates execution
to your source file.

## Common functions

The following functions are commonly used from within a test case body:

* atf_check: This is probably the most useful function for shell-based tests.
  It may need some experience to get it right, but it allows, in one line, to
  check the execution of a command.  Where check means: validate exit code,
  stdout and stderr.  This is just a wrapper over atf-check, so please refer to
  for more details.

* atf_check_equal value1 value2: Check that the two values are equal and, if
  not, abort execution.

* atf_expect_*: Same as their C counterparts; see above.

* atf_fail reason: Explicitly marks the test case as failed and aborts it.

* atf_skip reason: Explicitly marks the test case as skipped and exits.

* atf_pass: Explicitly markts the test case as passed and exits.

* atf_get_srcdir: Prints the path to the directory where the test case lives.
  Use as $(atf_get_srcdir)/my-static-data-file.


## How do I atfify a plain test program?

Let's suppose you have a program to exercise a particular piece of code.
Conceptually this implements a test but it does not use atf at all.  For

    #include <err.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>

    /* This test program exercises the snprintf function. */

    int main(void)
        char buf[1024];

        printf("Testing integers");
        snprintf(buf, sizeof(buf), "%d", 3);
        if (strcmp(buf, "3") != 0)
            errx(EXIT_FAILURE, "%d failed");
        snprintf(buf, sizeof(buf), "a %d b", 5);
        if (strcmp(buf, "a 5 b") != 0)
            errx(EXIT_FAILURE, "%d failed");

        printf("Testing strings");
        snprintf(buf, sizeof(buf), "%s", "foo");
        if (strcmp(buf, "foo") != 0)
            errx(EXIT_FAILURE, "%s failed");
        snprintf(buf, sizeof(buf), "a %s b", "bar");
        if (strcmp(buf, "a bar b") != 0)
            errx(EXIT_FAILURE, "%s failed");

        return EXIT_SUCCESS;

To convert this program into an atf test program, use the template above and
keep this in mind:

* Split the whole main function into separate test cases.  In this scenario, the
  calls to printf(3) delimit a good granularity for the test cases: one for the
  integer formatter, one for the string formatter, etc.

* Use the ATF_CHECK* and/or atf_tc_fail functions to do the comparisons and
  report errors.  Neither errx nor any other error reporting and program
  termination functions (read: err, errx, warn, warnx, exit, abor) are to be
  used at all.

The result would look like:

    #include <atf-c.h>
    #include <stdio.h>

    ATF_TC(tc, integer_formatter);
    ATF_TC_HEAD(tc, integer_formatter)
        atf_tc_set_md_var(tc, "descr", "Validates the %d formatter");
    ATF_TC_BODY(tc, integer_formatter)
        char buf[1024];

        snprintf(buf, sizeof(1024), "%d", 3);
        ATF_CHECK_STREQ("3", buf);

        snprintf(buf, sizeof(1024), "a %d b", 5);
        ATF_CHECK_STREQ("a 5 b", buf);

    ATF_TC(tc, string_formatter);
    ATF_TC_HEAD(tc, string_formatter)
        atf_tc_set_md_var(tc, "descr", "Validates the %s formatter");
    ATF_TC_BODY(tc, string_formatter)
        char buf[1024];

        snprintf(buf, sizeof(1024), "%s", "foo");
        ATF_CHECK_STREQ("foo", buf);

        snprintf(buf, sizeof(1024), "a %s b", "bar");
        ATF_CHECK_STREQ("a bar b", buf);

        ATF_TP_ADD_TC(tp, integer_formatter);
        ATF_TP_ADD_TC(tp, string_formatter);

Which can later be invoked as any of:

    $ atf-run snprintf_test | atf-report  # Normal execution method.
    $ ./snprintf_test integer_formatter  # For DEBUGGING only.
    $ ./snprintf_test string_formatter  # For DEBUGGING only.

## How do I write a test case for an unfixed PR?

Use the "expectations" mechanism to define part of the test case as faulty,
crashy, etc.  This is for two reasons:

* As long as the bug still exists, he test case will be reported as an "expected
  failure".  Such expected failures do not count towards the success or failure
  of the whole test suite.

* When the bug gets fixed, the bug will not trigger any more in the test case,
  and thus the expectation of failure will not be met any more.  At this point
  the test case will start raising a regular failure, which is usually addressed
  by either just removing the expect_* calls.

For example, suppose we have PR lib/1 that reports a condition in which
snprintf() does the wrong formatting when using %s, and PR lib/2 that mentions
that another snprintf() call using %d with number 5 causes a segfault.  We could

    #include <atf-c.h>
    #include <signal.h>
    #include <stdio.h>

    ATF_TC_WITHOUT_HEAD(tc, integer_formatter);
    ATF_TC_BODY(tc, integer_formatter)
        char buf[1024];

        snprintf(buf, sizeof(buf), "Hello %d\n", 1);
        ATF_CHECK_STREQ("Hello 1", buf);

        atf_tc_expect_signal(SIGSEGV, "PR lib/2: %%d with 5 causes a crash");
        snprintf(buf, sizeof(buf), "Hello %d\n", 5);
        ATF_CHECK_STREQ("Hello 5", buf);

    ATF_TC_WITHOUT_HEAD(tc, string_formatter);
    ATF_TC_BODY(tc, string_formatter)
        char buf[1024];

        snprintf(buf, sizeof(buf), "Hello %s\n", "world!");
        atf_tc_expect_failure("PR lib/1: %%s does not work");
        ATF_CHECK_STREQ("Hello world!", buf);

        ATF_TP_ADD_TC(tp, integer_formatter);
        ATF_TP_ADD_TC(tp, string_formatter);

## Do I need to remove temporary files?

No.  atf-run does this automatically for you, because it runs every test program
in its own temporary subdirectory.

## When do I use ATF_CHECK and when ATF_REQUIRE?

ATF_CHECK logs errors but does not abort the execution of the test program.
ATF_REQUIRE logs errors in a similar way but immediately terminates the

You can use this distinction in the following way: use ATF_REQUIRE to check the
code that "prepares" your test case.  Use ATF_CHECK to do the actual
functionality tests once all the set up has been performed.  For example:

    ATF_TC_BODY(getline) {
        FILE *f;
        char buf[1024];

        /* Opening the file is not part of the functionality under test, but it
         * must succeed before we actually test the relevant code. */
        ATF_REQUIRE((f = fopen("foo")) != NULL);

        ATF_CHECK(getline(f, buf, sizeof(buf)) > 0);
        ATF_CHECK_STREQ("line 1", buf);

        ATF_CHECK(getline(f, buf, sizeof(buf)) > 0);
        ATF_CHECK_STREQ("line 2", buf);

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