NAME

       Test::Fatal - incredibly simple helpers for testing code with exceptions

VERSION

       version 0.016

SYNOPSIS

         use Test::More;
         use Test::Fatal;

         use System::Under::Test qw(might_die);

         is(
           exception { might_die; },
           undef,
           "the code lived",
         );

         like(
           exception { might_die; },
           qr/turns out it died/,
           "the code died as expected",
         );

         isa_ok(
           exception { might_die; },
           'Exception::Whatever',
           'the thrown exception',
         );

DESCRIPTION

       Test::Fatal is an alternative to the popular Test::Exception.  It does much less, but
       should allow greater flexibility in testing exception-throwing code with about the same
       amount of typing.

       It exports one routine by default: "exception".

       Achtung!  "exception" intentionally does not manipulate the call stack.  User-written test
       functions that use "exception" must be careful to avoid false positives if exceptions use
       stack traces that show arguments.  For a more magical approach involving globally
       overriding "caller", see Test::Exception.

FUNCTIONS

   exception
         my $exception = exception { ... };

       "exception" takes a bare block of code and returns the exception thrown by that block.  If
       no exception was thrown, it returns undef.

       Achtung!  If the block results in a false exception, such as 0 or the empty string,
       Test::Fatal itself will die.  Since either of these cases indicates a serious problem with
       the system under testing, this behavior is considered a feature.  If you must test for
       these conditions, you should use Try::Tiny's try/catch mechanism.  (Try::Tiny is the
       underlying exception handling system of Test::Fatal.)

       Note that there is no TAP assert being performed.  In other words, no "ok" or "not ok"
       line is emitted.  It's up to you to use the rest of "exception" in an existing test like
       "ok", "isa_ok", "is", et cetera.  Or you may wish to use the "dies_ok" and "lives_ok"
       wrappers, which do provide TAP output.

       "exception" does not alter the stack presented to the called block, meaning that if the
       exception returned has a stack trace, it will include some frames between the code calling
       "exception" and the thing throwing the exception.  This is considered a feature because it
       avoids the occasionally twitchy "Sub::Uplevel" mechanism.

       Achtung!  This is not a great idea:

         sub exception_like(&$;$) {
             my ($code, $pattern, $name) = @_;
             like( &exception($code), $pattern, $name );
         }

         exception_like(sub { }, qr/foo/, 'foo appears in the exception');

       If the code in the "..." is going to throw a stack trace with the arguments to each
       subroutine in its call stack (for example via "Carp::confess", the test name, "foo appears
       in the exception" will itself be matched by the regex.  Instead, write this:

         like( exception { ... }, qr/foo/, 'foo appears in the exception' );

       If you really want a test function that passes the test name, wrap the arguments in an
       array reference to hide the literal text from a stack trace:

         sub exception_like(&$) {
             my ($code, $args) = @_;
             my ($pattern, $name) = @$args;
             like( &exception($code), $pattern, $name );
         }

         exception_like(sub { }, [ qr/foo/, 'foo appears in the exception' ] );

       To aid in avoiding the problem where the pattern is seen in the exception because of the
       call stack, $Carp::MAxArgNums is locally set to -1 when the code block is called.  If you
       really don't want that, set it back to whatever value you like at the beginning of the
       code block.  Obviously, this solution doens't affect all possible ways that args of
       subroutines in the call stack might taint the test.  The intention here is to prevent some
       false passes from people who didn't read the documentation.  Your punishment for reading
       it is that you must consider whether to do anything about this.

       Achtung: One final bad idea:

         isnt( exception { ... }, undef, "my code died!");

       It's true that this tests that your code died, but you should really test that it died for
       the right reason.  For example, if you make an unrelated mistake in the block, like using
       the wrong dereference, your test will pass even though the code to be tested isn't really
       run at all.  If you're expecting an inspectable exception with an identifier or class,
       test that.  If you're expecting a string exception, consider using "like".

   success
         try {
           should_live;
         } catch {
           fail("boo, we died");
         } success {
           pass("hooray, we lived");
         };

       "success", exported only by request, is a Try::Tiny helper with semantics identical to
       "finally", but the body of the block will only be run if the "try" block ran without
       error.

       Although almost any needed exception tests can be performed with "exception", success
       blocks may sometimes help organize complex testing.

   dies_ok
   lives_ok
       Exported only by request, these two functions run a given block of code, and provide TAP
       output indicating if it did, or did not throw an exception.  These provide an easy upgrade
       path for replacing existing unit tests based on "Test::Exception".

       RJBS does not suggest using this except as a convenience while porting tests to use
       Test::Fatal's "exception" routine.

         use Test::More tests => 2;
         use Test::Fatal qw(dies_ok lives_ok);

         dies_ok { die "I failed" } 'code that fails';

         lives_ok { return "I'm still alive" } 'code that does not fail';

AUTHOR

       Ricardo Signes <rjbs@cpan.org>

CONTRIBUTORS

       •   David Golden <dagolden@cpan.org>

       •   Graham Knop <haarg@haarg.org>

       •   Jesse Luehrs <doy@tozt.net>

       •   Joel Bernstein <joel@fysh.org>

       •   Karen Etheridge <ether@cpan.org>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2010 by Ricardo Signes.

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