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Test::Cmd
Perl module for portable testing of commands and scripts

Test::Cmd - Perl module for portable testing of commands and scripts


NAME

Test::Cmd - Perl module for portable testing of commands and scripts


SYNOPSIS


  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', rwflag);

  $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, funcref);

  $test->fail(condition);

  $test->fail(condition, funcref);

  $test->fail(condition, funcref, caller);

  $test->no_result(condition);

  $test->no_result(condition, funcref);

  $test->no_result(condition, funcref, caller);

  $test->stdout;

  $test->stdout(run_number);

  $test->stderr;

  $test->stderr(run_number);

  $test->diff();

  $test->match($lines, $matches);

  $test->match_exact(\@lines, \@matches);

  $test->match_exact($lines, $matches);

  $test->match_regex(\@lines, \@regexes);

  $test->match_regex($lines, $regexes);

  sub func {

        my ($self, $lines, $matches) = @_;

        # code to match $line and $matches

  }

  $test->match_sub(\&func);

  $test->match_sub(sub { code to match $_[1] and $[2] });

  $test->here;


DESCRIPTION

The Test::Cmd module provides a framework for portable automated testing of executable commands and scripts (in any language, not just Perl), especially commands and scripts that require file system interaction.

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.

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.

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 should be handled by the test itself or a subclass specific to the program under test.

The Test::Cmd module may be used in conjunction with the Test module to report test results in a format suitable for the Test::Harness module. A typical use would be to call the Test::Cmd methods to prepare and execute the test, and call the ok() method exported by the Test module to test the conditions:


    use Test;

    use Test::Cmd;

    BEGIN { $| = 1; plan => 3 }

    $test = Test::Cmd->new(prog => 'test_program', workdir => '');

    ok($test);

    $wrote_file = $test->write('input_file', <<'EOF');

    This is input to test_program,

    which we expect to process this

    and exit successfully (status 0).

    EOF

    ok($wrote_file);

    $test->run(args => 'input_file');

    ok($? == 0);

Alternatively, the Test::Cmd module provides pass(), fail(), and no_result() methods that report test results for use with the Aegis change management system. These methods terminate the test immediately, reporting PASSED, FAILED, or NO RESULT respectively, and exiting with status 0 (success), 1 or 2 respectively. This allows 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):


    use Test::Cmd;

    $test = Test::Cmd->new(prog => 'test_program', workdir => '');

    Test::Cmd->no_result(! $test);

    $wrote_file = $test->write('input_file', <<'EOF');

    This is input to test_program,

    which we expect to process this

    and exit successfully (status 0).

    EOF

    $test->no_result(! $wrote_file);

    $test->run(args => 'input_file');

    $test->fail($? != 0);

    $test->pass;

It is not a good idea to intermix the two reporting models. If you use the Test module and its ok method, do not use the Test::Cmd pass, fail or no_result methods, and vice versa.


METHODS

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 the specified directory tree writable (rwflag == TRUE) or not writable (rwflag == FALSE).

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
Specifies the program to be used to interpret prog as a script, for this run only. This does not change the $test-&interpreter> value of the test environment.

prog
Specifies the executable program or script to be run, for this run only. This does not change the $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.

diff
Not Yet Implemented.

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.

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 or match_regex methods supplied by the Test::Cmd module:

        $test->match_sub(\&Test::Cmd::match_exact);

        $test->match_sub(\&Test::Cmd::match_regex);

The match_exact and match_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);

        $test_exact = Test::Cmd->new(match_sub => \&match_exact);

        $test_regex = Test::Cmd->new(match_sub => \&match_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.)


ENVIRONMENT

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
If set to a true value, all temporary working directories will be preserved on exit, regardless of success or failure of the test. The full path names of all temporary working directories will be reported on error output.

PRESERVE_FAIL
If set to a true value, all temporary working directories will be preserved on exit from a failed test. The full path names of all temporary working directories will be reported on error output.

PRESERVE_NO_RESULT
If set to a true value, all temporary working directories will be preserved on exit from a test for which there is no result. The full path names of all temporary working directories will be reported on error output.

PRESERVE_PASS
If set to a true value, all temporary working directories will be preserved on exit from a successful test. The full path names of all temporary working directories will be reported on error output.

VERBOSE
When set to a true value, enables verbose reporting of various internal things (path names, exact command line being executed, etc.).


PORTABLE TESTS

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.

Use the 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.

Use 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.

Use 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.)

Avoid generating executable programs or scripts.
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.


SEE ALSO

perl(1), File::Find(3), File::Spec(3), Test(3), Test::Harness(3).

A rudimentary page for the Test::Cmd module is available at:


        http://www.baldmt.com/Test-Cmd/


AUTHORS

Steven Knight, knight@baldmt.com


COPYRIGHT

Copyright 1999-2000 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.


ACKNOWLEDGEMENTS

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
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