tutorial.pod

SinFP是一种新的识别对方计算机操作系统类型的工具

First, we can calculate the plan dynamically using the C<plan()>
function.

    use Test::More;
    use Date::ICal;

    my %ICal_Dates = (
        ...same as before...
    );

    # For each key in the hash we're running 8 tests.
    plan tests => keys %ICal_Dates * 8;

Or to be even more flexible, we use C<no_plan>.  This means we're just
running some tests, don't know how many. [6]

    use Test::More 'no_plan';   # instead of tests => 32

now we can just add tests and not have to do all sorts of math to
figure out how many we're running.


=head2 Informative names

Take a look at this line here

    ok( defined $ical,            "new(ical => '$ical_str')" );

we've added more detail about what we're testing and the ICal string
itself we're trying out to the name.  So you get results like:

    ok 25 - new(ical => '19971024T120000')
    ok 26 -   and it's the right class
    ok 27 -   year()
    ok 28 -   month()
    ok 29 -   day()
    ok 30 -   hour()
    ok 31 -   min()
    ok 32 -   sec()

if something in there fails, you'll know which one it was and that
will make tracking down the problem easier.  So try to put a bit of
debugging information into the test names.

Describe what the tests test, to make debugging a failed test easier
for you or for the next person who runs your test.


=head2 Skipping tests

Poking around in the existing Date::ICal tests, I found this in
F<t/01sanity.t> [7]

    #!/usr/bin/perl -w

    use Test::More tests => 7;
    use Date::ICal;

    # Make sure epoch time is being handled sanely.
    my $t1 = Date::ICal->new( epoch => 0 );
    is( $t1->epoch, 0,          "Epoch time of 0" );

    # XXX This will only work on unix systems.
    is( $t1->ical, '19700101Z', "  epoch to ical" );

    is( $t1->year,  1970,       "  year()"  );
    is( $t1->month, 1,          "  month()" );
    is( $t1->day,   1,          "  day()"   );

    # like the tests above, but starting with ical instead of epoch
    my $t2 = Date::ICal->new( ical => '19700101Z' );
    is( $t2->ical, '19700101Z', "Start of epoch in ICal notation" );

    is( $t2->epoch, 0,          "  and back to ICal" );

The beginning of the epoch is different on most non-Unix operating
systems [8].  Even though Perl smooths out the differences for the most
part, certain ports do it differently.  MacPerl is one off the top of
my head. [9] We I<know> this will never work on MacOS.  So rather than
just putting a comment in the test, we can explicitly say it's never
going to work and skip the test.

    use Test::More tests => 7;
    use Date::ICal;

    # Make sure epoch time is being handled sanely.
    my $t1 = Date::ICal->new( epoch => 0 );
    is( $t1->epoch, 0,          "Epoch time of 0" );

    SKIP: {
        skip('epoch to ICal not working on MacOS', 6) 
            if $^O eq 'MacOS';

        is( $t1->ical, '19700101Z', "  epoch to ical" );

        is( $t1->year,  1970,       "  year()"  );
        is( $t1->month, 1,          "  month()" );
        is( $t1->day,   1,          "  day()"   );

        # like the tests above, but starting with ical instead of epoch
        my $t2 = Date::ICal->new( ical => '19700101Z' );
        is( $t2->ical, '19700101Z', "Start of epoch in ICal notation" );

        is( $t2->epoch, 0,          "  and back to ICal" );
    }

A little bit of magic happens here.  When running on anything but
MacOS, all the tests run normally.  But when on MacOS, C<skip()> causes
the entire contents of the SKIP block to be jumped over.  It's never
run.  Instead, it prints special output that tells Test::Harness that
the tests have been skipped.

    1..7
    ok 1 - Epoch time of 0
    ok 2 # skip epoch to ICal not working on MacOS
    ok 3 # skip epoch to ICal not working on MacOS
    ok 4 # skip epoch to ICal not working on MacOS
    ok 5 # skip epoch to ICal not working on MacOS
    ok 6 # skip epoch to ICal not working on MacOS
    ok 7 # skip epoch to ICal not working on MacOS

This means your tests won't fail on MacOS.  This means less emails
from MacPerl users telling you about failing tests that you know will
never work.  You've got to be careful with skip tests.  These are for
tests which don't work and I<never will>.  It is not for skipping
genuine bugs (we'll get to that in a moment).

The tests are wholly and completely skipped. [10]  This will work.

    SKIP: {
        skip("I don't wanna die!");

        die, die, die, die, die;
    }


=head2 Todo tests

Thumbing through the Date::ICal man page, I came across this:

   ical

       $ical_string = $ical->ical;

   Retrieves, or sets, the date on the object, using any
   valid ICal date/time string.

"Retrieves or sets".  Hmmm, didn't see a test for using C<ical()> to set
the date in the Date::ICal test suite.  So I'll write one.

    use Test::More tests => 1;
    use Date::ICal;

    my $ical = Date::ICal->new;
    $ical->ical('20201231Z');
    is( $ical->ical, '20201231Z',   'Setting via ical()' );

run that and I get

    1..1
    not ok 1 - Setting via ical()
    #     Failed test (- at line 6)
    #          got: '20010814T233649Z'
    #     expected: '20201231Z'
    # Looks like you failed 1 tests of 1.

Whoops!  Looks like it's unimplemented.  Let's assume we don't have
the time to fix this. [11] Normally, you'd just comment out the test
and put a note in a todo list somewhere.  Instead, we're going to
explicitly state "this test will fail" by wrapping it in a C<TODO> block.

    use Test::More tests => 1;

    TODO: {
        local $TODO = 'ical($ical) not yet implemented';

        my $ical = Date::ICal->new;
        $ical->ical('20201231Z');

        is( $ical->ical, '20201231Z',   'Setting via ical()' );
    }

Now when you run, it's a little different:

    1..1
    not ok 1 - Setting via ical() # TODO ical($ical) not yet implemented
    #          got: '20010822T201551Z'
    #     expected: '20201231Z'

Test::More doesn't say "Looks like you failed 1 tests of 1".  That '#
TODO' tells Test::Harness "this is supposed to fail" and it treats a
failure as a successful test.  So you can write tests even before
you've fixed the underlying code.

If a TODO test passes, Test::Harness will report it "UNEXPECTEDLY
SUCCEEDED".  When that happens, you simply remove the TODO block with
C<local $TODO> and turn it into a real test.


=head2 Testing with taint mode.

Taint mode is a funny thing.  It's the globalest of all global
features.  Once you turn it on, it affects I<all> code in your program
and I<all> modules used (and all the modules they use).  If a single
piece of code isn't taint clean, the whole thing explodes.  With that
in mind, it's very important to ensure your module works under taint
mode.

It's very simple to have your tests run under taint mode.  Just throw
a C<-T> into the C<#!> line.  Test::Harness will read the switches
in C<#!> and use them to run your tests.

    #!/usr/bin/perl -Tw

    ...test normally here...

So when you say C<make test> it will be run with taint mode and
warnings on.


=head1 FOOTNOTES

=over 4

=item 1

The first number doesn't really mean anything, but it has to be 1.
It's the second number that's important.

=item 2

For those following along at home, I'm using version 1.31.  It has
some bugs, which is good -- we'll uncover them with our tests.

=item 3

You can actually take this one step further and test the manual
itself.  Have a look at B<Test::Inline> (formerly B<Pod::Tests>).

=item 4

Yes, there's a mistake in the test suite.  What!  Me, contrived?

=item 5

We'll get to testing the contents of lists later.

=item 6

But what happens if your test program dies halfway through?!  Since we
didn't say how many tests we're going to run, how can we know it
failed?  No problem, Test::More employs some magic to catch that death
and turn the test into a failure, even if every test passed up to that
point.

=item 7

I cleaned it up a little.

=item 8

Most Operating Systems record time as the number of seconds since a
certain date.  This date is the beginning of the epoch.  Unix's starts
at midnight January 1st, 1970 GMT.

=item 9

MacOS's epoch is midnight January 1st, 1904.  VMS's is midnight,
November 17th, 1858, but vmsperl emulates the Unix epoch so it's not a
problem.

=item 10

As long as the code inside the SKIP block at least compiles.  Please
don't ask how.  No, it's not a filter.

=item 11

Do NOT be tempted to use TODO tests as a way to avoid fixing simple
bugs!

=back

=head1 AUTHORS

Michael G Schwern E<lt>[e-mail]<gt> and the perl-qa dancers!

=head1 COPYRIGHT

Copyright 2001 by Michael G Schwern E<lt>[e-mail]<gt>.

This documentation is free; you can redistribute it and/or modify it
under the same terms as Perl itself.

Irrespective of its distribution, all code examples in these files
are hereby placed into the public domain.  You are permitted and
encouraged to use this code in your own programs for fun
or for profit as you see fit.  A simple comment in the code giving
credit would be courteous but is not required.

=cut