Test::Cmd - Perl module for portable testing of commands and scripts
use Test::Cmd;
$test = Test::Cmd->new(prog => 'program_or_script_to_test', interpreter => 'script_interpreter', string => 'identifier_string', workdir => '', subdir => 'dir', match_sub => $code_ref, verbose => 1);
$test->verbose(1);
$test->prog('program_or_script_to_test');
$test->basename(@suffixlist);
$test->interpreter('script_interpreter');
$test->string('identifier string');
$test->workdir('prefix');
$test->workpath('subdir', 'file');
$test->subdir('subdir', ...); $test->subdir(['sub', 'dir'], ...);
$test->write('file', <<'EOF'); contents of file EOF $test->write(['subdir', 'file'], <<'EOF'); contents of file EOF
$test->read(\$contents, 'file'); $test->read(\@lines, 'file'); $test->read(\$contents, ['subdir', 'file']); $test->read(\@lines, ['subdir', 'file']);
$test->writable('dir'); $test->writable('dir', $rwflag); $test->writable('dir', $rwflag, \%errors);
$test->preserve(condition, ...);
$test->cleanup(condition);
$test->run(prog => 'program_or_script_to_test', interpreter => 'script_interpreter', chdir => 'dir', args => 'arguments', stdin => <<'EOF'); input to program EOF
$test->pass(condition); $test->pass(condition, \&func);
$test->fail(condition); $test->fail(condition, \&func); $test->fail(condition, \&func, $caller);
$test->no_result(condition); $test->no_result(condition, \&func); $test->no_result(condition, \&func, $caller);
$test->stdout; $test->stdout($run_number);
$test->stderr; $test->stderr($run_number);
$test->match(\@lines, \@matches); $test->match($lines, $matches);
$test->match_exact(\@lines, \@matches); $test->match_exact($lines, $matches);
$test->match_regex(\@lines, \@regexes); $test->match_regex($lines, $regexes);
$test->diff_exact(\@lines, \@matches, \@output); $test->diff_exact($lines, $matches, \@output);
$test->diff_regex(\@lines, \@regexes, \@output); $test->diff_regex($lines, $regexes, \@output);
sub func { my ($self, $lines, $matches) = @_; # code to match $lines and $matches } $test->match_sub(\&func); $test->match_sub(sub { code to match $_[1] and $_[2] });
$test->here;
The Test::Cmd
module provides a low-level framework for portable
automated testing of executable commands and scripts (in any language,
not just Perl), especially commands and scripts that interact with the
file system.
The Test::Cmd
module makes no assumptions about what constitutes
a successful or failed test. Attempting to read a file that doesn't
exist, for example, may or may not be an error, depending on the
software being tested.
Consequently, no Test::Cmd
methods (including the new()
method)
exit, die or throw any other sorts of exceptions (but they all do return
useful error indications). Exceptions or other error status should
be handled by a higher layer: a subclass of Test::Cmd
, or another
testing framework such as the Test
or Test::Simple
Perl modules,
or by the test itself.
(That said, see the Test::Cmd::Common
module if you want a similar
module that provides exception handling, either to use directly in your
own tests, or as an example of how to use Test::Cmd
.)
In addition to running tests and evaluating conditions, the Test::Cmd
module manages and cleans up one or more temporary workspace
directories, and provides methods for creating files and directories in
those workspace directories from in-line data (that is, here-documents),
allowing tests to be completely self-contained. When used in
conjunction with another testing framework, the Test::Cmd
module can
function as a fixture (common startup code for multiple tests) for
simple management of command execution and temporary workspaces.
The Test::Cmd
module inherits File::Spec
methods
(file_name_is_absolute()
, catfile()
, etc.) to support writing
tests portably across a variety of operating and file systems.
A Test::Cmd
environment object is created via the usual invocation:
$test = Test::Cmd->new();
Arguments to the Test::Cmd::new
method are keyword-value pairs that
may be used to initialize the object, typically by invoking the same-named
method as the keyword.
As mentioned, because the Test::Cmd
module makes no assumptions
about what constitutes success or failure of a test, it can be used to
provide temporary workspaces, other file system interaction, or command
execution for a variety of testing frameworks. This section describes
how to use the Test::Cmd
with several different higher-layer testing
frameworks.
Note that you should not intermix multiple testing frameworks in a single testing script.
Test::Harness
The Test::Cmd
module may be used in tests that print results in a
format suitable for the standard Perl Test::Harness
module:
use Test::Cmd;
print "1..5\n";
$test = Test::Cmd->new(prog => 'test_program', workdir => ''); if ($test) { print "ok 1\n"; } else { print "not ok 1\n"; }
$input = <<_EOF; test_program should process this input and exit successfully (status 0). _EOF_
$wrote_file = $test->write('input_file', $input); if ($wrote_file) { print "ok 2\n"; } else { print "not ok 2\n"; }
$test->run(args => '-x input_file'); if ($? == 0) { print "ok 3\n"; } else { print "not ok 3\n"; }
$wrote_file = $test->write('input_file', $input); if ($wrote_file) { print "ok 4\n"; } else { print "not ok 4\n"; }
$test->run(args => '-y input_file'); if ($? == 0) { print "ok 5\n"; } else { print "not ok 5\n"; }
Several other Perl modules simplify the use of Test::Harness
by eliminating the need to hand-code the print
statements and
test numbers. The Test
module, the Test::Simple
module, and
the Test::More
module all export an ok()
subroutine to test
conditions. Here is how the above example would look rewritten to use
Test::Simple
:
use Test::Simple tests => 5; use Test::Cmd;
$test = Test::Cmd->new(prog => 'test_program', workdir => ''); ok($test, "creating Test::Cmd object");
$input = <<_EOF; test_program should process this input and exit successfully (status 0). _EOF_
$wrote_file = $test->write('input_file', $input); ok($wrote_file, "writing input_file");
$test->run(args => '-x input_file'); ok($? == 0, "executing test_program -x input_file");
$wrote_file = $test->write('input_file', $input); ok($wrote_file, "writing input_file");
$test->run(args => '-y input_file'); ok($? == 0, "executing test_program -y input_file");
Test::Unit
The Perl Test::Unit
package provides a procedural testing interface
modeled after a testing framework widely used in the eXtreme Programming
development methodology. The Test::Cmd
module can function as part
of a Test::Unit
fixture that can set up workspaces as needed for a
set of tests. This avoids having to repeat code to re-initialize an
input file multiple times:
use Test::Unit; use Test::Cmd; my $test; $input = <<'EOF'; test_program should process this input and exit successfully (status 0). EOF sub set_up { $test = Test::Cmd->new(prog => 'test_program', workdir => ''); $test->write('input_file', $input); } sub test_x { my $result = $test->run(args => '-x input_file'); assert($result == 0, "failed test_x\n"); } sub test_y { my $result = $test->run(args => '-y input_file'); assert($result == 0, "failed test_y\n"); } create_suite(); run_suite;
Note that, because the Test::Cmd
module takes care of cleaning up
temporary workspaces on exit, there is no need to remove explicitly the
workspace in a tear_down
subroutine. (There may, of course, be other
things in the test that need a tear_down
subroutine.)
Alternatively, the Test::Cmd
module provides pass()
, fail()
,
and no_result()
methods that can be used to provide an appropriate
exit status and simple printed indication for a test. These methods
terminate the test immediately, reporting PASSED
, FAILED
, or
NO RESULT
respectively, and exiting with status 0 (success), 1 or 2
respectively.
The separate fail()
and no_result()
methods allow for a
distinction between an actual failed test and a test that could not be
properly evaluated because of an external condition (such as a full file
system or incorrect permissions).
The exit status values happen to match the requirements of the Aegis change management system, and the printed strings are based on existing Aegis conventions. They are not really Aegis-specific, however, and provide a simple, useful starting point if you don't already have another testing framework:
use Test::Cmd;
$test = Test::Cmd->new(prog => 'test_program', workdir => ''); Test::Cmd->no_result(! $test);
$input = <<EOF; test_program should process this input and exit successfully (status 0). EOF
$wrote_file = $test->write('input_file', $input); $test->no_result(! $wrote_file);
$test->run(args => '-x input_file'); $test->fail($? != 0);
$wrote_file = $test->write('input_file', $input); $test->no_result(! $wrote_file);
$test->run(args => '-y input_file'); $test->fail($? != 0);
$test->pass;
Note that the separate Test::Cmd::Common
wrapper module can simplify
the above example even further by taking care of common exception
handling cases within the testing object itself.
use Test::Cmd::Common;
$test = Test::Cmd::Common->new(prog => 'test_program', workdir => '');
$input = <<EOF; test_program should process this input and exit successfully (status 0). EOF
$wrote_file = $test->write('input_file', $input);
$test->run(args => '-x input_file');
$wrote_file = $test->write('input_file', $input);
$test->run(args => '-y input_file');
$test->pass;
See the Test::Cmd::Common
module for details.
Methods supported by the Test::Cmd
module include:
new
Create a new Test::Cmd
environment. Arguments with which to initialize
the environment are passed in as keyword-value pairs. Fails if a
specified temporary working directory or subdirectory cannot be created.
Does NOT die or exit on failure, but returns FALSE if the test environment
object cannot be created.
verbose
Sets the verbose level for the environment object to the specified value.
prog
Specifies the executable program or script to be tested. Returns the absolute path name of the current program or script.
basename
Returns the basename of the current program or script. Any specified arguments are a list of file suffixes that may be stripped from the basename.
interpreter
Specifies the program to be used to interpret prog
as a script.
Returns the current value of interpreter
.
string
Specifies an identifier string for the functionality being tested to be printed on failure or no result.
workdir
When an argument is specified, creates a temporary working directory
with the specified name. If the argument is a NULL string (''),
the directory is named testcmd
by default, followed by the
unique ID of the executing process.
Returns the absolute pathname to the temporary working directory, or FALSE if the directory could not be created.
workpath
Returns the absolute path name to a subdirectory or file under the current temporary working directory by concatenating the temporary working directory name with the specified arguments.
subdir
Creates new subdirectories under the temporary working dir, one for
each argument. An argument may be an array reference, in which case the
array elements are concatenated together using the File::Spec-&
catfile>
method. Subdirectories multiple levels deep must be created via a
separate argument for each level:
$test->subdir('sub', ['sub', 'dir'], [qw(sub dir ectory)]);
Returns the number of subdirectories actually created.
write
Writes the specified text (second argument) to the specified file name (first argument). The file name may be an array reference, in which case all the array elements except the last are subdirectory names to be concatenated together. The file is created under the temporary working directory. Any subdirectories in the path must already exist.
read
Reads the contents of the specified file name (second argument) into the scalar or array referred to by the first argument. The file name may be an array reference, in which case all the array elements except the last are subdirectory names to be concatenated together. The file is assumed to be under the temporary working directory unless it is an absolute path name.
Returns TRUE on successfully opening and reading the file, FALSE otherwise.
writable
Makes every file and directory within the specified directory tree
writable (rwflag
== TRUE) or not writable (rwflag
== FALSE). The
default is to make the directory tree writable. Optionally fills in the
supplied hash reference with a hash of path names that could not have
their permissions set appropriately, with the reason why each could not
be set.
preserve
Arranges for the temporary working directories for the specified
Test::Cmd
environment to be preserved for one or more conditions.
If no conditions are specified, arranges for the temporary working
directories to be preserved for all conditions.
cleanup
Removes any temporary working directories for the specified Test::Cmd
environment. If the environment variable PRESERVE
was set when
the Test::Cmd
module was loaded, temporary working directories are
not removed. If any of the environment variables PRESERVE_PASS
,
PRESERVE_FAIL
, or PRESERVE_NO_RESULT
were set when the Test::Cmd
module was loaded, then temporary working directories are not removed
if the test passed, failed, or had no result, respectively. Temporary
working directories are also preserved for conditions specified via the
preserve
method.
Typically, this method is not called directly, but is used when the script exits to clean up temporary working directories as appropriate for the exit status.
run
Runs a test of the program or script for the test environment. Standard
output and error output are saved for future retrieval via the stdout
and stderr
methods.
Arguments are supplied as keyword-value pairs:
args
Specifies the command-line arguments to be supplied to the program or script under test for this run:
$test->run(args => 'arg1 arg2');
chdir
Changes directory to the path specified as the value argument:
$test->run(chdir => 'xyzzy');
If the specified path is not an absolute path name (begins with '/'
on Unix systems), then the subdirectory is relative to the temporary
working directory for the environment ($test-&
workdir>). Note that,
by default, the Test::Cmd
module does NOT chdir to the temporary
working directory, so to execute the test under the temporary working
directory, you must specify an explicit chdir
to the current directory:
$test->run(chdir => '.'); # Unix-specific
$test->run(chdir => $test->curdir); # portable
interpreter
prog
as a script,
for this run only. This does not change the $test-&
interpreter>
value of the test environment.
prog
$test-&
prog> value of the test environment.
stdin
Pipes the specified value (string or array ref) to the program or script under test for this run:
$test->run(stdin => <<_EOF_); input to the program under test _EOF_
Returns the exit status of the program or script.
pass
Exits the test successfully. Reports "PASSED" on the error output and exits with a status of 0. If a condition is supplied, only exits the test if the condition evaluates TRUE. If a function reference is supplied, executes the function before reporting and exiting.
fail
Exits the test unsuccessfully. Reports "FAILED test of {string} at line {line} of {file}." on the error output and exits with a status of 1. If a condition is supplied, only exits the test if the condition evaluates TRUE. If a function reference is supplied, executes the function before reporting and exiting. If a caller level is supplied, prints a simple calling trace N levels deep as part of reporting the failure.
no_result
Exits the test with an indeterminate result (the test could not be performed due to external conditions such as, for example, a full file system). Reports "NO RESULT for test of {string} at line {line} of {file}." on the error output and exits with a status of 2. If a condition is supplied, only exits the test if the condition evaluates TRUE. If a function reference is supplied, executes the function before reporting and exiting. If a caller level is supplied, prints a simple calling trace N levels deep as part of reporting the failure.
stdout
Returns the standard output from the specified run number. If there is no
specified run number, then returns the standard output of the last run.
Returns the standard output as either a scalar or an array of output
lines, as appropriate for the calling context. Returns undef
if
there has been no test run.
stderr
Returns the error output from the specified run number. If there is
no specified run number, then returns the error output of the last run.
Returns the error output as either a scalar or an array of output lines,
as apporpriate for the calling context. Returns undef
if there has
been no test run.
match
Matches one or more input lines against an equal number of expected lines
using the currently-registered line-matching function. The default
line-matching function is the match_regex
method, which means that
the default is to match lines against regular expressions.
match_exact
Compares two arrays of lines for exact matches. The arguments are passed in as either scalars, in which case each is split on newline boundaries, or as array references. An unequal number of lines in the two arrays fails immediately and returns FALSE before any comparisons are performed.
Returns TRUE if each line matched its corresponding line in the other array, FALSE otherwise.
match_regex
Matches one or more input lines against an equal number of regular expressions. The arguments are passed in as either scalars, in which case each is split on newline boundaries, or as array references. Trailing newlines are stripped from each line and regular expression. An unequal number of lines and regular expressions fails immediately and returns FALSE before any comparisons are performed. Comparison is performed for each entire line, that is, with each regular expression anchored at both the start of line (^) and end of line ($).
Returns TRUE if each line matched each regular expression, FALSE otherwise.
diff_exact
Diffs two arrays of lines in a manner similar to the UNIX diff(1)
utility.
If the Algorithm::DiffOld
package is installed on the local system,
output describing the differences between the input lines and the
matching lines, in diff(1)
format, is saved to the $output
array
reference. In the diff output, the expected output lines are considered
the "old" (left-hand) file, and the actual output is considered the
"new" (right-hand) file.
If the Algorithm::DiffOld
package is not installed on the local
system, the Expected and Actual contents are saved as-is to the
$output
array reference.
The lines
and matches
arguments are passed in as either scalars,
in which case each is split on newline boundaries, or as array
references. Trailing newlines are stripped from each line and regular
expression.
Returns TRUE if each line matched its corresponding line in the expected
matches, FALSE otherwise, in order to conform to the conventions of the
match
method.
Typical invocation:
if (! $test->diff_exact($test->stdout, \@expected_lines, \@diff)) { print @diff; }
diff_regex
Diffs one or more input lines against one or more regular expressions
in a manner similar to the UNIX diff(1)
utility.
If the Algorithm::DiffOld
package is installed on the local system,
output describing the differences between the input lines and the
matching lines, in diff(1)
format, is saved to the $output
array
reference. In the diff output, the expected output lines are considered
the "old" (left-hand) file, and the actual output is considered the
"new" (right-hand) file.
If the Algorithm::DiffOld
package is not installed on the local
system, the Expected and Actual contents are saved as-is to the
$output
array reference.
The lines
and regexes
arguments are passed in as either scalars,
in which case each is split on newline boundaries, or as array
references. Trailing newlines are stripped from each line and regular
expression. Comparison is performed for each entire line, that is, with
each regular expression anchored at both the start of line (^) and end
of line ($).
Returns TRUE if each line matched each regular expression, FALSE
otherwise, in order to conform to the conventions of the match
method.
Typical invocation:
if (! $test->diff_regex($test->stdout, \@expected_lines, \@diff)) { print @diff; }
match_sub
Registers the specified code reference as the line-matching function
to be called by the match
method. This can be a user-supplied
subroutine, or the match_exact
, match_regex
, diff_exact
, or
diff_regex
methods supplied by the Test::Cmd
module:
$test->match_sub(\&Test::Cmd::match_exact);
$test->match_sub(\&Test::Cmd::match_regex);
$test->match_sub(\&Test::Cmd::diff_exact);
$test->match_sub(\&Test::Cmd::diff_regex);
The match_exact
, match_regex
, diff_exact
and diff_regex
subroutine names are exportable from the Test::Cmd
module, and may be
specified at object initialization:
use Test::Cmd qw(match_exact match_regex diff_exact diff_regex); $test_exact = Test::Cmd->new(match_sub => \&match_exact); $test_regex = Test::Cmd->new(match_sub => \&match_regex); $test_exact = Test::Cmd->new(match_sub => \&diff_exact); $test_regex = Test::Cmd->new(match_sub => \&diff_regex);
here
Returns the absolute path name of the current working directory.
(This is essentially the same as the Cwd::cwd
method, except that the
Test::Cmd::here
method preserves the directory separators exactly
as returned by the underlying operating-system-dependent method.
The Cwd::cwd
method canonicalizes all directory separators to '/',
which makes for consistent path name representations within Perl, but may
mess up another program or script to which you try to pass the path name.)
Several environment variables affect the default values in a newly created
Test::Cmd
environment object. These environment variables must be set
when the module is loaded, not when the object is created.
PRESERVE
PRESERVE_FAIL
PRESERVE_NO_RESULT
PRESERVE_PASS
VERBOSE
Although the Test::Cmd
module is intended to make it easier to write
portable tests for portable utilities that interact with file systems,
it is still very easy to write non-portable tests if you're not careful.
The best and most comprehensive set of portability guidelines is the standard "Writing portable Perl" document at:
http://www.perl.com/pub/doc/manual/html/pod/perlport.html
To reiterate one important point from the "WpP" document: Not all Perl
programs have to be portable. If the program or script you're testing
is UNIX-specific, you can (and should) use the Test::Cmd
module to
write UNIX-specific tests.
That having been said, here are some hints that may help keep your tests portable, if that's a requirement.
Test::Cmd-&
here> method for current directory path.
The normal Perl way to fetch the current working directory is to use the
Cwd::cwd
method. Unfortunately, the Cwd::cwd
method canonicalizes
the path name it returns, changing the native directory separators into
the forward slashes favored by Perl and UNIX. For most Perl scripts,
this makes a great deal of sense and keeps code uncluttered.
Passing in a file name that has had its directory separators altered,
however, may confuse the command or script under test, or make it
difficult to compare output from the command or script with an expected
result. The Test::Cmd::here
method returns the absolute path name of
the current working directory, like Cwd::cwd
, but does not manipulate
the returned path in any way.
File::Spec
methods for manipulating path names.
The File::Spec
module provides a system-independent interface for
manipulating path names. Because the Test::Cmd
class is a sub-class
of the File::Spec
class, you can use these methods directly as follows:
if (! Test::Cmd->file_name_is_absolute($prog)) { my $prog = Test::Cmd->catfile(Test::Cmd->here, $prog); }
For details about the available methods and their use, see the
documentation for the File::Spec
module and its sub-modules, especially
the File::Spec::Unix
modules.
Config
for file-name suffixes, where possible.
The standard Config
module provides values that reflect the file-name
suffixes on the system for which the Perl executable was built.
This provides convenient portability for situations where a file name
may have different extensions on different systems:
$foo_exe = "foo$Config{_exe}"; ok(-f $foo_exe);
(Unfortunately, there is no existing $Config
value that specifies
the suffix for a directly-executable Perl script.)
How to make a file or script executable varies widely from system to system, some systems using file name extensions to indicate executability, others using a file permission bit. The differences are complicated to accomodate in a portable test script. The easiest way to deal with this complexity is to avoid it if you can.
If your test somehow requires executing a script that you generate
from the test itself, the best way is to generate the script in Perl
and then explicitly feed it to the Perl executable on the local system.
To be maximally portable, use the $^X
variable instead of hard-coding
"perl" into the string you execute:
$line = "This is output from the generated perl script."; $test->write('script', <<EOF); print STDOUT "$line\\n"; EOF $output = `$^X script`; ok($output eq "$line\n");
This completely avoids having to make the script
file itself
executable. (Since you're writing your test in Perl, it's safe to assume
that Perl itself is executable.)
If you must generate a directly-executable script, then use the
$Config{'startperl'}
variable at the start of the script to generate
the appropriate magic that will execute it as a Perl script:
use Config; $line = "This is output from the generated perl script."; $test->write('script', <<EOF); $Config{'startperl'}; print STDOUT "$line\\n"; EOF chdir($test->workdir); chmod(0755, 'script'); # POSIX-SPECIFIC $output = `script`; ok($output eq "$line\n");
Addtional hints on writing portable tests are welcome.
perl(1), Algorithm::DiffOld(3), File::Find(3), File::Spec(3), Test(3), Test::Cmd::Common(3), Test::Harness(3), Test::More(3), Test::Simple(3), Test::Unit(3).
A rudimentary page for the Test::Cmd
module is available at:
http://www.baldmt.com/Test-Cmd/
The most involved example of using the Test::Cmd
package to test
a real-world application is the cons-test
testing suite for the
Cons software construction utility. The suite uses a sub-class of
Test::Cmd::Common
(which in turn is a sub-class of Test::Cmd
)
to provide common, application-specific infrastructure across a
large number of end-to-end application tests. The suite, and other
information about Cons, is available at:
http://www.dsmit.com/cons
Steven Knight, knight@baldmt.com
Copyright 1999-2001 Steven Knight. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
Thanks to Greg Spencer for the inspiration to create this package and the initial draft of its implementation as a specific testing package for the Cons software construction utility. Information about Cons is available at:
http://www.dsmit.com/cons/
The general idea of managing temporary working directories in this way,
as well as the test reporting of the pass
, fail
and no_result
methods, come from the testing framework invented by Peter Miller for
his Aegis project change supervisor. Aegis is an excellent bit of work
which integrates creation and execution of regression tests into the
software development process. Information about Aegis is available at:
http://www.tip.net.au/~millerp/aegis.html
Thanks to Michael Schwern for all of the thoughtful work he's put into
Perl's standard testing methodology, including the Test::Simple
and
Test::More
modules, and enhancement and maintenance of the Test
and Test::Harness
modules. Thanks also to Christian Lemburg for
the impressively complete Test::Unit
framework of modules. Ideas
from both have helped keep Test::Cmd
flexible enough to be useful in
multiple testing frameworks.