NAME

Test::Expander - Expansion of test functionalities that appear to be frequently used while testing.

SYNOPSIS

    # Tries to automatically determine, which class / module and method / subroutine are to be tested,
    # creates neither a temporary directory, nor a temporary file:
    use Test::Expander;

    # Tries to automatically determine, which class / module and method / subroutine are to be tested.
    # The determined (and hence exported) values are displayed in green,
    # the undetermined (and hence unexported) ones in red:
    use Test::Expander -color => { exported => 'green', unexported => 'red' };

    # Tries to automatically determine, which class / module and method / subroutine are to be tested.
    # Both determined and undetermined values are displayed uncolorized:
    use Test::Expander -color => { exported => undef, unexported => undef };

    # Tries to automatically determine, which class / module and method / subroutine are to be tested,
    # creates both a temporary directory and a temporary file preventing their removal after execution:
    use Test::Expander -tempdir => { CLEANUP => 0 }, -tempfile => { UNLINK => 0 };

    # Tries to automatically determine, which class / module and method / subroutine are to be tested,
    # creates neither a temporary directory, nor a temporary file,
    # passes the option '-srand' to Test2::V0 changing the random seed to the current time in seconds:
    use Test::Expander -srand => time;

    # Class is supplied explicitly, tries to automatically determine method / subroutine to be tested,
    # creates a temporary directory with name corresponing to the template supplied, does not create temporary file:
    use Test::Expander -target => 'My::Class', -tempdir => { TEMPLATE => 'my_dir.XXXXXXXX' };

    # Does not try to determine, which class / module and method / subroutine are to be tested,
    # creates neither a temporary directory, nor a temporary file:
    use Test::Expander -target => undef;

    # Tries to automatically determine, which class / module is to be tested,
    # does not determine method / subroutine to be tested,
    # creates neither a temporary directory, nor a temporary file:
    use Test::Expander -method => undef;

    # Tries to automatically determine, which class / module is to be tested,
    # does not create temporary file, creates a temporary directory and
    # adds directories 'dir0' and 'dir1' located therein on top of the directory list used by the Perl interpreter
    # for search of modules to be loaded. In other words, "unshifts" these directories to the @INC array:
    # PLEASE CONSIDER THE SINGLE QUOTES APPLIED BELOW!
    use Test::Expander
      -lib => [
        'path( $TEMP_DIR )->child( qw( dir0 ) )->stringify',
        'path( $TEMP_DIR )->child( qw( dir1 ) )->stringify',
      ],
      -tempdir => {};

    # Override the builtin 'close' in the name space of explicitly supplied class / module to be tested:
    my $close_success;
    use Test::Expander
      -builtins => { close => sub { $close_success ? CORE::close( shift ) : 0 } },
      -target   => 'My::Class';

    # Activates immediate stop of test execution if any assertion fails:
    use Test::Expander -bail => 1;

DESCRIPTION

The primary objective of Test::Expander is to provide additional convenience while testing based on Test2::V0 considering boilerplate aspects that seem to be important (to the author) in notable number of cases. These are among other things:

Repeated application of class / module and / or method / function to be tested. This, of course, can be stored in additional variables declared somewhere at the very beginning of test.

Doing so, any refactoring including renaming of this class and / or method leads to the necessity to find and then to update all test files containing these names.

If, however, both of these values can be determined from the path and base name of the current test file and saved in the exported read-only variables $CLASS and $METHOD, the only effort necessary in case of such renaming is a single change of path and / or base name of the corresponding test file.

An additional benefit of suggested approach is a better readability of tests, where chunks like
```
    Foo::Bar->baz( $arg0, $arg1 )
```
now look like
```
    $CLASS->$METHOD( $arg0, $arg1 )
```
and hence clearly manifest that this chunk is about the testee.
The frequent necessity of introduction of temporary directory and / or temporary file usually leads to the usage of modules File::Temp::tempdir or Path::Tiny providing the methods / funtions tempdir and tempfile.

This, however, can significantly be simplified (and the size of test file can be reduced) requesting such introduction via the options supported by Test::Expander:
```
    use Test::Expander -tempdir => {}, -tempfile => {};
```
Another fuctionality frequently used in tests relates to the work with files and directories: reading, writing, creation, etc. Because almost all features required in such cases are provided by Path::Tiny, some functions of this module are also exported from Test::Expander.
To provide a really environment-independent testing, we might need a possibility to run our tests in a clean environment, where only explicitly mentioned environment variables are set and environment variables from the "outside world" cannot affect the execution of tests. This can also be achieved manually by manipulation of %ENV hash at the very beginning of tests. However, even ignoring the test code inflation, this might be (in fact - is) necessary in many tests belonging to one and the same module, so that a possibility to outsource the definition of test environment provided by Test::Expander makes tests smaller, more maintainable, and much more reliable.
I stole the idea of subtest selection from Test::Builder::SubtestSelection. That's why the subtest selection supported by Test::Expander is partially compatible with the implementation provided by Test::Builder::SubtestSelection. The term "partially" means that the option --subtest can only be applied to selection by name not by number.

In general the subtest selection allows the execution of required subtests identified by their names and / or by their numbers before test running. At the command-line prove runs your test script and the subtest selection is based on the values given to the options --subtest_name (alias --subtest - in the Test::Builder::SubtestSelection style) and --subtest_number. Both options can be applied repeatedly and mixed together so that some tests can be selected by names and other ones by numbers.

In both cases the options have to be supplied as arguments to the test script. To do so separate the arguments from prove's own arguments with the arisdottle (::).
Another idea inspired by other module namely by Test::Most is the idea of immediate stop of test file execution if one of the tests fails.

This feature can be applied both for the whole test file using the -bail option
```
    use Test::Expander -bail => 1;
```
and for a part of it using the functions bail_on_failure and restore_failure_handler to activate and deactivate this reaction, correspondingly.
- Selection by name
  
  The selection by name means that the value supplied along with --subtest_name option is compared with all subtest names in your test and only those, which names match this value in terms of regular expression, will be executed. If this value cannot be treated as a valid regular expression, meta characters therein are properly quoted so that the RegEx match is in any case possible.
  
  Assuming the test script t/my_test.t contains
```
    use strict;
    use warnings;

    use Test::Expander;

    plan( 3 );

    subtest 'my higher level subtest without RegEx meta characters in name' => sub {
      # some test function calls
    };

    subtest 'my next higher level subtest' => sub {
      subtest 'my embedded subtest' => sub {
        subtest 'my deepest subtest' => sub {
          # some test function calls
        };
        # some test function calls
      };
      # some test function calls
    };

    # some test function calls

    subtest 'my subtest with [' => sub {
      # some test function calls
    };
```
  Then, if the subtest my next higher level subtest with all embedded subtests and the subtest my subtest with [ should be executed, the corresponding prove call can look like one of the following variants:
```
    prove -v -b t/basic.t :: --subtest_name 'next|embedded|deepest' --subtest_name '['
    prove -v -b t/basic.t :: --subtest_name 'next' --subtest_name 'embedded' --subtest_name 'deepest' --subtest_name '['
```
  This kind of subtest selection is pretty convenient but has a significant restriction: you cannot select an embedded subtest without its higher-level subtests. I.e. if you would try to run the following command
```
    prove -v -b t/basic.t :: --subtest_name 'deepest' --subtest_name '['
```
  the subtest my next higher level subtest including all embedded subtests will be skipped, so that even the subtest my deepest subtest will not be executed although this was your goal.
  
  This restriction, however, can be avoided using the subtest selection by number.
- Selection by number
  
  The selection by number means that the value supplied along with --subtest_number option is the sequence of numbers representing required subtest in the test file. Let's add to the source code of t/my_test.t some comments illustrating the numbers of each subtest:
```
    use strict;
    use warnings;

    use Test::Expander;

    plan( 3 );

    subtest 'my higher level subtest without RegEx meta characters in name' => sub { # subtest No. 0
      # some test function calls
    };

    subtest 'my next higher level subtest' => sub { # subtest No. 1
      subtest 'my embedded subtest' => sub {        # subtest No. 0 in subtest No. 1
        subtest 'my deepest subtest' => sub {       # subtest No. 0 in subtest No. 0 in subtest No. 1
          # some test function calls
        };
        # some test function calls
      };
      # some test function calls
    };

    # some test function calls

    subtest 'my subtest with [' => sub { # subtest No. 2
      # some test function calls
    };
```
  Taking this into consideration we can combine subtest numbers starting from the highest level and separate single levels by the slash sign to get the unique number of any subtest we intend to execute. Doing so, if we only want to execute the subtests my deepest subtest (its number is 1/0/0) and my subtest with [ (its number is 2), this can easily be done with the following command:
```
    prove -v -b t/basic.t :: --subtest_number '1/0/0' --subtest_number '2'
```

Test::Expander combines all advanced possibilities provided by Test2::V0 with some specific functions only available in the older module Test::More (which allows a smooth migration from Test::More-based tests to Test2::V0-based ones) and handy functions from some other modules often used in test suites.

Furthermore, this module allows to automatically recognize the class / module to be tested (see variable $CLASS below) so that in contrast to Test2::V0 you do not need to specify this explicitly if the path to the test file is in accordance with the name of class / module to be tested i.e. file t/Foo/Bar/baz.t corresponds to class / module Foo::Bar.

If such automated recognition is not intended, this can be deactivated by explicitly supplied undefined class / module name along with the option -target.

A similar recognition is provided in regard to the method / subroutine to be tested (see variables $METHOD and $METHOD_REF below) if the base name (without extension) of test file is identical with the name of this method / subroutine i.e. file t/Foo/Bar/baz.t corresponds to method / subroutine Foo::Bar::bar.

Finally, a configurable setting of specific environment variables is provided so that there is no need to hard-code this in the test itself.

The following options are accepted:

Options specific for this module only are always expected to have values and their meaning is:
- -bail - activates immediate stop of test file execution if any test case in this file fails. The expected value is boolean. Defaults to false i.e. the execution continues even if tests fail.
  
  Even if activated, this behaviour can be deactivated at any point in the test file using the function restore_failure_handler.
- -builtins - overrides builtins in the name space of class / module to be tested. The expected value is a hash reference, where keys are the names of builtins and the values are code references overriding default behavior.
- -color - controls colorization of read-only variables $CLASS, $METHOD, and $METHOD_REF in the test notification header. The expected value is a hash reference, the only supported keys are exported and unexported:
  - exported
    
    Contains either a string describing the foreground color, in which these variables are displayed if they are being exported, or undef in no colorization is required in such case.
    
    Defaults to 'cyan'.
  - unexported
    
    The same as above, but for the case if these variables remains undefined and unexported.
    
    Defaults to 'magenta'.
- -lib - prepends directory list used by the Perl interpreter for search of modules to be loaded (i.e. the @INC array) with values supplied in form of array reference. Each element of this array is evaluated using string eval so that any valid expression evaluated to string is supported if it is based on modules used by Test::Expander or any module loaded before.
  
  Among other things this provides a possibility to temporary expand the module search path by directories located in the temporary directory if the latter is defined with the option -tempdir (see below).
  
  -lib is interpreted as the very last option, that's why the variables defined by Test::Expander for export e.g. $TEMP_DIR can be used in the expressions determining such directories (see SYNOPSYS above).
- -method - prevents any attempt to automatically determine method / subroutine to be tested. If the value supplied along with this option is defined and found in the class / module to be test (see -target below), this will be considered such method / subroutine so that the variables $METHOD and $METHOD_REF (see description of exported variables below) will be imported and accessible in test. If this value is undef, these variables are not imported.
- -target - identical to the same-named option of Test2::V0 and, if contains a defined value, has the same purpose namely the explicit definition of the class / module to be tested as the value. However, if its value is undef, this is not passed through to Test2::V0 so that no class / module will be loaded and the variable $CLASS will not be imported at all.
- -tempdir - activates creation of a temporary directory. The value has to be a hash reference with content as explained in File::Temp::tempdir. This means, you can control the creation of temporary directory by passing of necessary parameters in form of a hash reference or, if the default behavior is required, simply pass the empty hash reference as the option value.
- -tempfile - activates creation of a temporary file. The value has to be a hash reference with content as explained in File::Temp::tempfile. This means, you can control the creation of temporary file by passing of necessary parameters in form of a hash reference or, if the default behavior is required, simply pass the empty hash reference as the option value.
All other valid options (i.e. arguments starting with the dash sign -) are forwarded to Test2::V0 along with their values.

Options without values are not supported; in case of their passing an exception is raised.
If an argument cannot be recognized as an option, an exception is raised.

The automated recognition of name of class / module to be tested can only work if the test file is located in the corresponding subdirectory. For instance, if the class / module to be tested is Foo::Bar::Baz, then the folder with test files related to this class / module should be t/Foo/Bar/Baz or xt/Foo/Bar/Baz (the name of the top-level directory in this relative name - t, or xt, or my_test is not important) - otherwise the module name cannot be put into the exported variable $CLASS and, if you want to use this variable, should be supplied as the value of -target:

    use Test::Expander -target => 'Foo::Bar::Baz';

This recognition can explicitly be deactivated if the value of -target is undef, so that no class / module will be loaded and, correspondingly, the variables $CLASS, $METHOD, and $METHOD_REF will not be exported.

Furthermore, the automated recognition of the name of the method / subroutine to be tested only works if the file containing the class / module mentioned above exists and if this class / module has the method / subroutine with the same name as the test file base name without the extension. If this is the case, the exported variables $METHOD and $METHOD_REF contain the name of method / subroutine to be tested and its reference, correspondingly, otherwise both variables are neither evaluated nor exported.

Also in this case evaluation and export of the variables $METHOD and $METHOD_REF can be prevented by passing of undef as value of the option -method:

    use Test::Expander -target => undef;

Finally, Test::Expander supports testing inside of a clean environment containing only some clearly specified environment variables required for the particular test. Names and values of these environment variables should be configured in files, which names are identical with paths to single class / module levels or the method / subroutine to be tested, and the extension is always .env. For instance, if the test file name is t/Foo/Bar/Baz/myMethod.t, the following approach is applied:

if the file t/Foo.env exists, its content is used for the initialization of the test environment,
if the file t/Foo/Bar.env exists, its content is used either to extend the test environment initialized in the previous step or for its initialization if t/Foo.env does not exist,
if the file t/Foo/Bar/Baz.env exists, its content is used either to extend the test environment initialized in one of the previous steps or for its initialization if neither t/Foo.env nor t/Foo/Bar.env exist,
if the file t/Foo/Bar/Baz/myMethod.env exists, its content is used either to extend the test environment initialized in one of the previous steps or for its initialization if none of .env files mentioned above exist.

If the .env files existing on different levels have identical names of environment variables, the priority is the higher the later they have been detected. I.e. VAR = 'VALUE0' in t/Foo/Bar/Baz/myMethod.env overwrites VAR = 'VALUE1' in t/Foo/Bar/Baz.env.

If none of these .env files exist, the environment isn't changed by Test::Expander during the execution of t/Foo/Bar/Baz/myMethod.t.

An environment configuration file (.env file) is a line-based text file. Its content is interpreted as follows:

if such files don't exist, the %ENV hash remains unchanged;
otherwise, if at least one of such files exists, those elements of the %ENV hash are kept, which names are equal to names found in lines of .env file without values. All remaining elements of the %ENV hash gets emptied (without localization) and
- lines not matching the RegEx /^\w+\s*(?:=\s*\S|$)?/ (some alphanumeric characters representing a name of environment variable, optional blanks, optionally followed by the equal sign, again optional blanks, and at least one non-blank character representing the first character of environment variable value) are skipped;
- in all other lines the value of the environment variable is everything from the first non-blank character after the equal sign until end of the line; if this value is omitted, the corresponding environment variable remains unchanged as it originally was in the %ENV hash (if it existed there, of course);
- the cascading definition of environment variables can be used, which means that
  - during the evaluation of current line environment variables defined in the same file above can be applied. For example if such .env file contains
```
    VAR1 = 'ABC'
    VAR2 = lc( $ENV{ VAR1 } )
```
    and neither VAR1 nor VAR2 will be overwritten during the evaluation of subsequent lines in the same or other .env files, the %ENV hash will contain at least the following entries:
```
    VAR1 => 'ABC'
    VAR2 => 'abc'
```
  - during the evaluation of current line also environment variables defined in a higher-level .env file can be used. For example if t/Foo/Bar/Baz.env contains
```
    VAR0 = 'XYZ '
```
    and t/Foo/Bar/Baz/myMethod.env contains
```
    VAR1 = 'ABC'
    VAR2 = lc( $ENV{ VAR0 } . $ENV{ VAR1 } )
```
    and neither VAR0, nor VAR1, nor VAR2 will be overwritten during the evaluation of subsequent lines in the same or other .env files, the %ENV hash will contain at least the following entries:
```
    VAR0 => 'XYZ '
    VAR1 => 'ABC'
    VAR2 => 'xyz abc'
```
- the value of the environment variable (if provided) is evaluated by the string eval so that
  - constant values must be quoted;
  - variables and subroutines must not be quoted:
```
    NAME_CONST = 'VALUE'
    NAME_VAR   = $KNIB::App::MyApp::Constants::ABC
    NAME_FUNC  = join(' ', $KNIB::App::MyApp::Constants::DEF)
```

All environment variables set up in this manner are logged to STDOUT using note.

Another common feature within test suites is the creation of a temporary directory / file used as an isolated container for some testing actions. The module options -tempdir and -tempfile are fully syntactically compatible with File::Temp::tempdir / File::Temp::tempfile. They make sure that such temporary directory / file are created after use Test::Expander and that their names are stored in the variables $TEMP_DIR / $TEMP_FILE, correspondingly. Both temporary directory and file are removed by default after execution.

The following functions provided by this module are exported by default:

all functions exported by default from Test2::V0,
all functions exported by default from Test2::Tools::Explain,
some functions exported by default from Test::More and often used in older tests but not supported by Test2::V0:
- BAIL_OUT,
- is_deeply,
- new_ok,
- require_ok,
- use_ok.
some functions exported by default from Test::Exception and often used in older tests but not supported by Test2::V0:
- dies_ok,
- lives_ok,
- throws_ok.
some functions exported by default from Test2::Tools::Explain and often used in older tests but not supported by Test2::Tools::Explain:
- explain.
function exported by default from Const::Fast:
- const.
some functions exported by request from File::Temp:
- tempdir,
- tempfile,
some functions exported by request from Path::Tiny:
- cwd,
- path,

The following variables can be set and exported:

variable $CLASS containing the name of the class / module to be tested if the class / module recognition is not disable and possible,
variable $METHOD containing the name of the method / subroutine to be tested if the method / subroutine recognition is not disable and possible,
variable $METHOD_REF containing the reference to the subroutine to be tested if the method / subroutine recognition is not disable and possible,
variable $TEMP_DIR containing the name of a temporary directory created at compile time if the option -tempdir is supplied,
variable $TEMP_FILE containing the name of a temporary file created at compile time if the option -tempfile is supplied.
variable $TEST_FILE containing the absolute name of the current test file (if any). In fact its content is identical with the content of special token __FILE__, but only in the test file itself! If, however, you need the test file name in a test submodule or in a .env file belonging to this test, __FILE__ can no longer be applied - whereas $TEST_FILE is there.

All variables mentioned above are read-only after their export. In this case they are logged to STDOUT using note.

If any of the variables $CLASS, $METHOD, and $METHOD_REF is undefined and hence not exported, this is reported at the very begin of test execution.

CAVEATS

Test::Expander is recommended to be the very first module in your test file.

The only known exception is when some actions performed on the module level (e.g. determination of constants) rely upon results of other actions (e.g. mocking of built-ins).

To explain this let us assume that your test file should globally mock the built-in close (if this is only required in the name space of class / module to be tested, the option -builtin should be used instead!) to verify if the testee properly reacts both on its success and failure. For this purpose a reasonable implementation might look as follows:
```
    my $close_success;
    BEGIN {
      *CORE::GLOBAL::close = sub (*) { $close_success ? CORE::close( shift ) : 0 }
    }

    use Test::Expander;
```
Array elements of the value supplied along with the option -lib are evaluated using string eval so that constant strings would need duplicated quotes e.g.
```
    use Test::Expander -lib => [ q('my_test_lib') ];
```
If the value to be assigned to an environment variable after evaluation of an .env file is undefined, such assignment is skipped.
If Test::Expander is used in one-line mode (with the -e option), the variable $TEST_FILE is unset and not exported.

AUTHOR

Jurij Fajnberg, <fajnbergj at gmail.com>

BUGS

Please report any bugs or feature requests through the web interface at https://github.com/jsf116/Test-Expander/issues.

COPYRIGHT AND LICENSE

This program is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

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