atf/atf-c++/atf-c++.3

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.Dd May 11, 2025
.Dt ATF-C++ 3
.Os
.Sh NAME
.Nm atf-c++ ,
.Nm ATF_ADD_TEST_CASE ,
.Nm ATF_CHECK_ERRNO ,
.Nm ATF_FAIL ,
.Nm ATF_INIT_TEST_CASES ,
.Nm ATF_PASS ,
.Nm ATF_REQUIRE ,
.Nm ATF_REQUIRE_EQ ,
.Nm ATF_REQUIRE_ERRNO ,
.Nm ATF_REQUIRE_IN ,
.Nm ATF_REQUIRE_MATCH ,
.Nm ATF_REQUIRE_NOT_IN ,
.Nm ATF_REQUIRE_THROW ,
.Nm ATF_REQUIRE_THROW_RE ,
.Nm ATF_SKIP ,
.Nm ATF_TEST_CASE ,
.Nm ATF_TEST_CASE_BODY ,
.Nm ATF_TEST_CASE_CLEANUP ,
.Nm ATF_TEST_CASE_HEAD ,
.Nm ATF_TEST_CASE_NAME ,
.Nm ATF_TEST_CASE_USE ,
.Nm ATF_TEST_CASE_WITH_CLEANUP ,
.Nm ATF_TEST_CASE_WITHOUT_HEAD ,
.Nm atf::utils::cat_file ,
.Nm atf::utils::compare_file ,
.Nm atf::utils::copy_file ,
.Nm atf::utils::create_file ,
.Nm atf::utils::file_exists ,
.Nm atf::utils::fork ,
.Nm atf::utils::grep_collection ,
.Nm atf::utils::grep_file ,
.Nm atf::utils::grep_string ,
.Nm atf::utils::redirect ,
.Nm atf::utils::wait
.Nd C++ API to write ATF-based test programs
.Sh SYNOPSIS
.In atf-c++.hpp
.Fn ATF_ADD_TEST_CASE "tcs" "name"
.Fn ATF_CHECK_ERRNO "expected_errno" "bool_expression"
.Fn ATF_FAIL "reason"
.Fn ATF_INIT_TEST_CASES "tcs"
.Fn ATF_PASS
.Fn ATF_REQUIRE "expression"
.Fn ATF_REQUIRE_EQ "expected_expression" "actual_expression"
.Fn ATF_REQUIRE_ERRNO "expected_errno" "bool_expression"
.Fn ATF_REQUIRE_IN "element" "collection"
.Fn ATF_REQUIRE_MATCH "regexp" "string_expression"
.Fn ATF_REQUIRE_NOT_IN "element" "collection"
.Fn ATF_REQUIRE_THROW "expected_exception" "statement"
.Fn ATF_REQUIRE_THROW_RE "expected_exception" "regexp" "statement"
.Fn ATF_SKIP "reason"
.Fn ATF_TEST_CASE "name"
.Fn ATF_TEST_CASE_BODY "name"
.Fn ATF_TEST_CASE_CLEANUP "name"
.Fn ATF_TEST_CASE_HEAD "name"
.Fn ATF_TEST_CASE_NAME "name"
.Fn ATF_TEST_CASE_USE "name"
.Fn ATF_TEST_CASE_WITH_CLEANUP "name"
.Fn ATF_TEST_CASE_WITHOUT_HEAD "name"
.Ft void
.Fo atf::utils::cat_file
.Fa "const std::string& path"
.Fa "const std::string& prefix"
.Fc
.Ft bool
.Fo atf::utils::compare_file
.Fa "const std::string& path"
.Fa "const std::string& contents"
.Fc
.Ft void
.Fo atf::utils::copy_file
.Fa "const std::string& source"
.Fa "const std::string& destination"
.Fc
.Ft void
.Fo atf::utils::create_file
.Fa "const std::string& path"
.Fa "const std::string& contents"
.Fc
.Ft void
.Fo atf::utils::file_exists
.Fa "const std::string& path"
.Fc
.Ft pid_t
.Fo atf::utils::fork
.Fa "void"
.Fc
.Ft bool
.Fo atf::utils::grep_collection
.Fa "const std::string& regexp"
.Fa "const Collection& collection"
.Fc
.Ft bool
.Fo atf::utils::grep_file
.Fa "const std::string& regexp"
.Fa "const std::string& path"
.Fc
.Ft bool
.Fo atf::utils::grep_string
.Fa "const std::string& regexp"
.Fa "const std::string& path"
.Fc
.Ft void
.Fo atf::utils::redirect
.Fa "const int fd"
.Fa "const std::string& path"
.Fc
.Ft void
.Fo atf::utils::wait
.Fa "const pid_t pid"
.Fa "const int expected_exit_status"
.Fa "const std::string& expected_stdout"
.Fa "const std::string& expected_stderr"
.Fc
.Sh DESCRIPTION
ATF provides a C++ programming interface to implement test programs.
C++-based test programs follow this template:
.Bd -literal -offset indent
extern "C" {
\&... C-specific includes go here ...
}

\&... C++-specific includes go here ...

#include <atf-c++.hpp>

ATF_TEST_CASE(tc1);
ATF_TEST_CASE_HEAD(tc1)
{
    ... first test case's header ...
}
ATF_TEST_CASE_BODY(tc1)
{
    ... first test case's body ...
}

ATF_TEST_CASE_WITH_CLEANUP(tc2);
ATF_TEST_CASE_HEAD(tc2)
{
    ... second test case's header ...
}
ATF_TEST_CASE_BODY(tc2)
{
    ... second test case's body ...
}
ATF_TEST_CASE_CLEANUP(tc2)
{
    ... second test case's cleanup ...
}

ATF_TEST_CASE(tc3);
ATF_TEST_CASE_BODY(tc3)
{
    ... third test case's body ...
}

\&... additional test cases ...

ATF_INIT_TEST_CASES(tcs)
{
    ATF_ADD_TEST_CASE(tcs, tc1);
    ATF_ADD_TEST_CASE(tcs, tc2);
    ATF_ADD_TEST_CASE(tcs, tc3);
    ... add additional test cases ...
}
.Ed
.Ss Definition of test cases
Test cases have an identifier and are composed of three different parts:
the header, the body and an optional cleanup routine, all of which are
described in
.Xr atf-test-case 4 .
To define test cases, one can use the
.Fn ATF_TEST_CASE ,
.Fn ATF_TEST_CASE_WITH_CLEANUP
or the
.Fn ATF_TEST_CASE_WITHOUT_HEAD
macros, which take a single parameter specifying the test case's
name.
.Fn ATF_TEST_CASE ,
requires to define a head and a body for the test case,
.Fn ATF_TEST_CASE_WITH_CLEANUP
requires to define a head, a body and a cleanup for the test case and
.Fn ATF_TEST_CASE_WITHOUT_HEAD
requires only a body for the test case.
It is important to note that these
.Em do not
set the test case up for execution when the program is run.
In order to do so, a later registration is needed through the
.Fn ATF_ADD_TEST_CASE
macro detailed in
.Sx Program initialization .
.Pp
Later on, one must define the three parts of the body by means of three
functions.
Their headers are given by the
.Fn ATF_TEST_CASE_HEAD ,
.Fn ATF_TEST_CASE_BODY
and
.Fn ATF_TEST_CASE_CLEANUP
macros, all of which take the test case's name.
Following each of these, a block of code is expected, surrounded by the
opening and closing brackets.
.Pp
Additionally, the
.Fn ATF_TEST_CASE_NAME
macro can be used to obtain the name of the class corresponding to a
particular test case, as the name is internally managed by the library to
prevent clashes with other user identifiers.
Similarly, the
.Fn ATF_TEST_CASE_USE
macro can be executed on a particular test case to mark it as "used" and
thus prevent compiler warnings regarding unused symbols.
Note that
.Em you should never have to use these macros during regular operation.
.Ss Program initialization
The library provides a way to easily define the test program's
.Fn main
function.
You should never define one on your own, but rely on the
library to do it for you.
This is done by using the
.Fn ATF_INIT_TEST_CASES
macro, which is passed the name of the list that will hold the test cases.
This name can be whatever you want as long as it is a valid variable value.
.Pp
After the macro, you are supposed to provide the body of a function, which
should only use the
.Fn ATF_ADD_TEST_CASE
macro to register the test cases the test program will execute.
The first parameter of this macro matches the name you provided in the
former call.
.Ss Header definitions
The test case's header can define the meta-data by using the
.Fn set_md_var
method, which takes two parameters: the first one specifies the
meta-data variable to be set and the second one specifies its value.
Both of them are strings.
.Ss Configuration variables
The test case has read-only access to the current configuration variables
by means of the
.Ft bool
.Fn has_config_var
and the
.Ft std::string
.Fn get_config_var
methods, which can be called in any of the three parts of a test case.
.Ss Access to the source directory
It is possible to get the path to the test case's source directory from any
of its three components by querying the
.Sq srcdir
configuration variable.
.Ss Requiring kernel modules
Aside from the
.Va require.kmods
meta-data variable available in the header only, one can also check for
additional kernel modules in the test case's body by using the
.Fn require_kmod
function, which takes the name of a single module.
If it is not found, the test case will be automatically skipped.
.Ss Requiring programs
Aside from the
.Va require.progs
meta-data variable available in the header only, one can also check for
additional programs in the test case's body by using the
.Fn require_prog
function, which takes the base name or full path of a single binary.
Relative paths are forbidden.
If it is not found, the test case will be automatically skipped.
.Ss Test case finalization
The test case finalizes either when the body reaches its end, at which
point the test is assumed to have
.Em passed ,
or at any explicit call to
.Fn ATF_PASS ,
.Fn ATF_FAIL
or
.Fn ATF_SKIP .
These three macros terminate the execution of the test case immediately.
The cleanup routine will be processed afterwards in a completely automated
way, regardless of the test case's termination reason.
.Pp
.Fn ATF_PASS
does not take any parameters.
.Fn ATF_FAIL
and
.Fn ATF_SKIP
take a single string that describes why the test case failed or
was skipped, respectively.
It is very important to provide a clear error message in both cases so that
the user can quickly know why the test did not pass.
.Ss Expectations
Everything explained in the previous section changes when the test case
expectations are redefined by the programmer.
.Pp
Each test case has an internal state called
.Sq expect
that describes what the test case expectations are at any point in time.
The value of this property can change during execution by any of:
.Bl -tag -width indent
.It Fn expect_death "reason"
Expects the test case to exit prematurely regardless of the nature of the
exit.
.It Fn expect_exit "exitcode" "reason"
Expects the test case to exit cleanly.
If
.Va exitcode
is not
.Sq -1 ,
the runtime engine will validate that the exit code of the test case
matches the one provided in this call.
Otherwise, the exact value will be ignored.
.It Fn expect_fail "reason"
Any failure (be it fatal or non-fatal) raised in this mode is recorded.
However, such failures do not report the test case as failed; instead, the
test case finalizes cleanly and is reported as
.Sq expected failure ;
this report includes the provided
.Fa reason
as part of it.
If no error is raised while running in this mode, then the test case is
reported as
.Sq failed .
.Pp
This mode is useful to reproduce actual known bugs in tests.
Whenever the developer fixes the bug later on, the test case will start
reporting a failure, signaling the developer that the test case must be
adjusted to the new conditions.
In this situation, it is useful, for example, to set
.Fa reason
as the bug number for tracking purposes.
.It Fn expect_pass
This is the normal mode of execution.
In this mode, any failure is reported as such to the user and the test case
is marked as
.Sq failed .
.It Fn expect_race "reason"
Any failure or timeout during the execution of the test case will be
considered as if a race condition has been triggered and reported as such.
If no problems arise, the test will continue execution as usual.
.It Fn expect_signal "signo" "reason"
Expects the test case to terminate due to the reception of a signal.
If
.Va signo
is not
.Sq -1 ,
the runtime engine will validate that the signal that terminated the test
case matches the one provided in this call.
Otherwise, the exact value will be ignored.
.It Fn expect_timeout "reason"
Expects the test case to execute for longer than its timeout.
.El
.Ss Helper macros for common checks
The library provides several macros that are very handy in multiple
situations.
These basically check some condition after executing a given statement or
processing a given expression and, if the condition is not met, they
automatically call
.Fn ATF_FAIL
with an appropriate error message.
.Pp
.Fn ATF_REQUIRE
takes an expression and raises a failure if it evaluates to false.
.Pp
.Fn ATF_REQUIRE_EQ
takes two expressions and raises a failure if the two do not evaluate to
the same exact value.
The common style is to put the expected value in the first parameter and the
actual value in the second parameter.
.Pp
.Fn ATF_REQUIRE_IN
takes an element and a collection and validates that the element is present in
the collection.
.Pp
.Fn ATF_REQUIRE_MATCH
takes a regular expression and a string and raises a failure if the regular
expression does not match the string.
.Pp
.Fn ATF_REQUIRE_NOT_IN
takes an element and a collection and validates that the element is not present
in the collection.
.Pp
.Fn ATF_REQUIRE_THROW
takes the name of an exception and a statement and raises a failure if
the statement does not throw the specified exception.
.Fn ATF_REQUIRE_THROW_RE
takes the name of an exception, a regular expression and a statement, and raises
a failure if the statement does not throw the specified exception and if the
message of the exception does not match the regular expression.
.Pp
.Fn ATF_CHECK_ERRNO
and
.Fn ATF_REQUIRE_ERRNO
take, first, the error code that the check is expecting to find in the
.Va errno
variable and, second, a boolean expression that, if evaluates to true,
means that a call failed and
.Va errno
has to be checked against the first value.
.Ss Utility functions
The following functions are provided as part of the
.Nm
API to simplify the creation of a variety of tests.
In particular, these are useful to write tests for command-line interfaces.
.Pp
.Ft void
.Fo atf::utils::cat_file
.Fa "const std::string& path"
.Fa "const std::string& prefix"
.Fc
.Bd -ragged -offset indent
Prints the contents of
.Fa path
to the standard output, prefixing every line with the string in
.Fa prefix .
.Ed
.Pp
.Ft bool
.Fo atf::utils::compare_file
.Fa "const std::string& path"
.Fa "const std::string& contents"
.Fc
.Bd -ragged -offset indent
Returns true if the given
.Fa path
matches exactly the expected inlined
.Fa contents .
.Ed
.Pp
.Ft void
.Fo atf::utils::copy_file
.Fa "const std::string& source"
.Fa "const std::string& destination"
.Fc
.Bd -ragged -offset indent
Copies the file
.Fa source
to
.Fa destination .
The permissions of the file are preserved during the code.
.Ed
.Pp
.Ft void
.Fo atf::utils::create_file
.Fa "const std::string& path"
.Fa "const std::string& contents"
.Fc
.Bd -ragged -offset indent
Creates
.Fa file
with the text given in
.Fa contents .
.Ed
.Pp
.Ft void
.Fo atf::utils::file_exists
.Fa "const std::string& path"
.Fc
.Bd -ragged -offset indent
Checks if
.Fa path
exists.
.Ed
.Pp
.Ft pid_t
.Fo atf::utils::fork
.Fa "void"
.Fc
.Bd -ragged -offset indent
Forks a process and redirects the standard output and standard error of the
child to files for later validation with
.Fn atf::utils::wait .
Fails the test case if the fork fails, so this does not return an error.
.Ed
.Pp
.Ft bool
.Fo atf::utils::grep_collection
.Fa "const std::string& regexp"
.Fa "const Collection& collection"
.Fc
.Bd -ragged -offset indent
Searches for the regular expression
.Fa regexp
in any of the strings contained in the
.Fa collection .
This is a template that accepts any one-dimensional container of strings.
.Ed
.Pp
.Ft bool
.Fo atf::utils::grep_file
.Fa "const std::string& regexp"
.Fa "const std::string& path"
.Fc
.Bd -ragged -offset indent
Searches for the regular expression
.Fa regexp
in the file
.Fa path .
The variable arguments are used to construct the regular expression.
.Ed
.Pp
.Ft bool
.Fo atf::utils::grep_string
.Fa "const std::string& regexp"
.Fa "const std::string& str"
.Fc
.Bd -ragged -offset indent
Searches for the regular expression
.Fa regexp
in the string
.Fa str .
.Ed
.Ft void
.Fo atf::utils::redirect
.Fa "const int fd"
.Fa "const std::string& path"
.Fc
.Bd -ragged -offset indent
Redirects the given file descriptor
.Fa fd
to the file
.Fa path .
This function exits the process in case of an error and does not properly mark
the test case as failed.
As a result, it should only be used in subprocesses of the test case; specially
those spawned by
.Fn atf::utils::fork .
.Ed
.Pp
.Ft void
.Fo atf::utils::wait
.Fa "const pid_t pid"
.Fa "const int expected_exit_status"
.Fa "const std::string& expected_stdout"
.Fa "const std::string& expected_stderr"
.Fc
.Bd -ragged -offset indent
Waits and validates the result of a subprocess spawned with
.Fn atf::utils::wait .
The validation involves checking that the subprocess exited cleanly and returned
the code specified in
.Fa expected_exit_status
and that its standard output and standard error match the strings given in
.Fa expected_stdout
and
.Fa expected_stderr .
.Pp
If any of the
.Fa expected_stdout
or
.Fa expected_stderr
strings are prefixed with
.Sq save: ,
then they specify the name of the file into which to store the stdout or stderr
of the subprocess, and no comparison is performed.
.Ed
.Sh ENVIRONMENT
The following variables are recognized by
.Nm
but should not be overridden other than for testing purposes:
.Pp
.Bl -tag -width ATFXBUILDXCXXFLAGSXX -compact
.It Va ATF_BUILD_CC
Path to the C compiler.
.It Va ATF_BUILD_CFLAGS
C compiler flags.
.It Va ATF_BUILD_CPP
Path to the C/C++ preprocessor.
.It Va ATF_BUILD_CPPFLAGS
C/C++ preprocessor flags.
.It Va ATF_BUILD_CXX
Path to the C++ compiler.
.It Va ATF_BUILD_CXXFLAGS
C++ compiler flags.
.El
.Sh EXAMPLES
The following shows a complete test program with a single test case that
validates the addition operator:
.Bd -literal -offset indent
#include <atf-c++.hpp>

ATF_TEST_CASE(addition);
ATF_TEST_CASE_HEAD(addition)
{
    set_md_var("descr", "Sample tests for the addition operator");
}
ATF_TEST_CASE_BODY(addition)
{
    ATF_REQUIRE_EQ(0, 0 + 0);
    ATF_REQUIRE_EQ(1, 0 + 1);
    ATF_REQUIRE_EQ(1, 1 + 0);

    ATF_REQUIRE_EQ(2, 1 + 1);

    ATF_REQUIRE_EQ(300, 100 + 200);
}

ATF_TEST_CASE(open_failure);
ATF_TEST_CASE_HEAD(open_failure)
{
    set_md_var("descr", "Sample tests for the open function");
}
ATF_TEST_CASE_BODY(open_failure)
{
    ATF_REQUIRE_ERRNO(ENOENT, open("non-existent", O_RDONLY) == -1);
}

ATF_TEST_CASE(known_bug);
ATF_TEST_CASE_HEAD(known_bug)
{
    set_md_var("descr", "Reproduces a known bug");
}
ATF_TEST_CASE_BODY(known_bug)
{
    expect_fail("See bug number foo/bar");
    ATF_REQUIRE_EQ(3, 1 + 1);
    expect_pass();
    ATF_REQUIRE_EQ(3, 1 + 2);
}

ATF_INIT_TEST_CASES(tcs)
{
    ATF_ADD_TEST_CASE(tcs, addition);
    ATF_ADD_TEST_CASE(tcs, open_failure);
    ATF_ADD_TEST_CASE(tcs, known_bug);
}
.Ed
.Sh SEE ALSO
.Xr atf-test-program 1 ,
.Xr atf-test-case 4