NAME

       "IO::Async::Test" - utility functions for use in test scripts

SYNOPSIS

        use Test::More tests => 1;
        use IO::Async::Test;

        use IO::Async::Loop;
        my $loop = IO::Async::Loop->new;
        testing_loop( $loop );

        my $result;

        $loop->do_something(
           some => args,

           on_done => sub {
              $result = the_outcome;
           }
        );

        wait_for { defined $result };

        is( $result, what_we_expected, 'The event happened' );

        ...

        my $buffer = "";
        my $handle = IO::Handle-> ...

        wait_for_stream { length $buffer >= 10 } $handle => $buffer;

        is( substr( $buffer, 0, 10, "" ), "0123456789", 'Buffer was correct' );

        my $result = wait_for_future( $stream->read_until( "\n" ) )->get;

DESCRIPTION

       This module provides utility functions that may be useful when writing test scripts for
       code which uses IO::Async (as well as being used in the IO::Async test scripts
       themselves).

       Test scripts are often synchronous by nature; they are a linear sequence of actions to
       perform, interspersed with assertions which check for given conditions. This goes against
       the very nature of IO::Async which, being an asynchronisation framework, does not provide
       a linear stepped way of working.

       In order to write a test, the "wait_for" function provides a way of synchronising the
       code, so that a given condition is known to hold, which would typically signify that some
       event has occurred, the outcome of which can now be tested using the usual testing
       primitives.

       Because the primary purpose of IO::Async is to provide IO operations on filehandles, a
       great many tests will likely be based around connected pipes or socket handles. The
       "wait_for_stream" function provides a convenient way to wait for some content to be
       written through such a connected stream.

FUNCTIONS

   testing_loop
          testing_loop( $loop )

       Set the IO::Async::Loop object which the "wait_for" function will loop on.

   wait_for
          wait_for { COND }

       Repeatedly call the "loop_once" method on the underlying loop (given to the "testing_loop"
       function), until the given condition function callback returns true.

       To guard against stalled scripts, if the loop indicates a timeout for 10 consequentive
       seconds, then an error is thrown.

   wait_for_stream
          wait_for_stream { COND } $handle, $buffer

       As "wait_for", but will also watch the given IO handle for readability, and whenever it is
       readable will read bytes in from it into the given buffer. The buffer is NOT initialised
       when the function is entered, in case data remains from a previous call.

       $buffer can also be a CODE reference, in which case it will be invoked being passed data
       read from the handle, whenever it is readable.

   wait_for_future
          $future = wait_for_future $future

       Since version 0.68.

       A handy wrapper around using "wait_for" to wait for a Future to become ready. The future
       instance itself is returned, allowing neater code.

AUTHOR

       Paul Evans <leonerd@leonerd.org.uk>