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NAME
Test2::API::Context - Object to represent a testing context.
DESCRIPTION
The context object is the primary interface for authors of testing tools written with
Test2. The context object represents the context in which a test takes place (File and
Line Number), and provides a quick way to generate events from that context. The context
object also takes care of sending events to the correct Test2::Hub instance.
SYNOPSIS
In general you will not be creating contexts directly. To obtain a context you should
always use "context()" which is exported by the Test2::API module.
use Test2::API qw/context/;
sub my_ok {
my ($bool, $name) = @_;
my $ctx = context();
if ($bool) {
$ctx->pass($name);
}
else {
$ctx->fail($name);
}
$ctx->release; # You MUST do this!
return $bool;
}
Context objects make it easy to wrap other tools that also use context. Once you grab a
context, any tool you call before releasing your context will inherit it:
sub wrapper {
my ($bool, $name) = @_;
my $ctx = context();
$ctx->diag("wrapping my_ok");
my $out = my_ok($bool, $name);
$ctx->release; # You MUST do this!
return $out;
}
CRITICAL DETAILS
you MUST always use the context() sub from Test2::API
Creating your own context via "Test2::API::Context->new()" will almost never produce a
desirable result. Use "context()" which is exported by Test2::API.
There are a handful of cases where a tool author may want to create a new context by
hand, which is why the "new" method exists. Unless you really know what you are doing
you should avoid this.
You MUST always release the context when done with it
Releasing the context tells the system you are done with it. This gives it a chance to
run any necessary callbacks or cleanup tasks. If you forget to release the context it
will try to detect the problem and warn you about it.
You MUST NOT pass context objects around
When you obtain a context object it is made specifically for your tool and any tools
nested within. If you pass a context around you run the risk of polluting other tools
with incorrect context information.
If you are certain that you want a different tool to use the same context you may pass
it a snapshot. "$ctx->snapshot" will give you a shallow clone of the context that is
safe to pass around or store.
You MUST NOT store or cache a context for later
As long as a context exists for a given hub, all tools that try to get a context will
get the existing instance. If you try to store the context you will pollute other
tools with incorrect context information.
If you are certain that you want to save the context for later, you can use a
snapshot. "$ctx->snapshot" will give you a shallow clone of the context that is safe
to pass around or store.
"context()" has some mechanisms to protect you if you do cause a context to persist
beyond the scope in which it was obtained. In practice you should not rely on these
protections, and they are fairly noisy with warnings.
You SHOULD obtain your context as soon as possible in a given tool
You never know what tools you call from within your own tool will need a context.
Obtaining the context early ensures that nested tools can find the context you want
them to find.
METHODS
$ctx->done_testing;
Note that testing is finished. If no plan has been set this will generate a Plan
event.
$clone = $ctx->snapshot()
This will return a shallow clone of the context. The shallow clone is safe to store
for later.
$ctx->release()
This will release the context. This runs cleanup tasks, and several important hooks.
It will also restore $!, $?, and $@ to what they were when the context was created.
Note: If a context is acquired more than once an internal refcount is kept.
"release()" decrements the ref count, none of the other actions of "release()" will
occur unless the refcount hits 0. This means only the last call to "release()" will
reset $?, $!, $@,and run the cleanup tasks.
$ctx->throw($message)
This will throw an exception reporting to the file and line number of the context.
This will also release the context for you.
$ctx->alert($message)
This will issue a warning from the file and line number of the context.
$stack = $ctx->stack()
This will return the Test2::API::Stack instance the context used to find the current
hub.
$hub = $ctx->hub()
This will return the Test2::Hub instance the context recognizes as the current one to
which all events should be sent.
$dbg = $ctx->trace()
This will return the Test2::EventFacet::Trace instance used by the context.
$ctx->do_in_context(\&code, @args);
Sometimes you have a context that is not current, and you want things to use it as the
current one. In these cases you can call "$ctx->do_in_context(sub { ... })". The
codeblock will be run, and anything inside of it that looks for a context will find
the one on which the method was called.
This DOES NOT affect context on other hubs, only the hub used by the context will be
affected.
my $ctx = ...;
$ctx->do_in_context(sub {
my $ctx = context(); # returns the $ctx the sub is called on
});
Note: The context will actually be cloned, the clone will be used instead of the
original. This allows the thread id, process id, and error variables to be correct
without modifying the original context.
$ctx->restore_error_vars()
This will set $!, $?, and $@ to what they were when the context was created. There is
no localization or anything done here, calling this method will actually set these
vars.
$! = $ctx->errno()
The (numeric) value of $! when the context was created.
$? = $ctx->child_error()
The value of $? when the context was created.
$@ = $ctx->eval_error()
The value of $@ when the context was created.
EVENT PRODUCTION METHODS
Which one do I use?
The "pass*" and "fail*" are optimal if they meet your situation, using one of them will
always be the most optimal. That said they are optimal by eliminating many features.
Method such as "ok", and "note" are shortcuts for generating common 1-task events based on
the old API, however they are forward compatible, and easy to use. If these meet your
needs then go ahead and use them, but please check back often for alternatives that may be
added.
If you want to generate new style events, events that do many things at once, then you
want the "*ev2*" methods. These let you directly specify which facets you wish to use.
$event = $ctx->pass()
$event = $ctx->pass($name)
This will send and return an Test2::Event::Pass event. You may optionally provide a
$name for the assertion.
The Test2::Event::Pass is a specially crafted and optimized event, using this will
help the performance of passing tests.
$true = $ctx->pass_and_release()
$true = $ctx->pass_and_release($name)
This is a combination of "pass()" and "release()". You can use this if you do not plan
to do anything with the context after sending the event. This helps write more clear
and compact code.
sub shorthand {
my ($bool, $name) = @_;
my $ctx = context();
return $ctx->pass_and_release($name) if $bool;
... Handle a failure ...
}
sub longform {
my ($bool, $name) = @_;
my $ctx = context();
if ($bool) {
$ctx->pass($name);
$ctx->release;
return 1;
}
... Handle a failure ...
}
my $event = $ctx->fail()
my $event = $ctx->fail($name)
my $event = $ctx->fail($name, @diagnostics)
This lets you send an Test2::Event::Fail event. You may optionally provide a $name and
@diagnostics messages.
Diagnostics messages can be simple strings, data structures, or instances of
Test2::EventFacet::Info::Table (which are converted inline into the
Test2::EventFacet::Info structure).
my $false = $ctx->fail_and_release()
my $false = $ctx->fail_and_release($name)
my $false = $ctx->fail_and_release($name, @diagnostics)
This is a combination of "fail()" and "release()". This can be used to write clearer
and shorter code.
sub shorthand {
my ($bool, $name) = @_;
my $ctx = context();
return $ctx->fail_and_release($name) unless $bool;
... Handle a success ...
}
sub longform {
my ($bool, $name) = @_;
my $ctx = context();
unless ($bool) {
$ctx->pass($name);
$ctx->release;
return 1;
}
... Handle a success ...
}
$event = $ctx->ok($bool, $name)
$event = $ctx->ok($bool, $name, \@on_fail)
NOTE: Use of this method is discouraged in favor of "pass()" and "fail()" which
produce Test2::Event::Pass and Test2::Event::Fail events. These newer event types are
faster and less crufty.
This will create an Test2::Event::Ok object for you. If $bool is false then an
Test2::Event::Diag event will be sent as well with details about the failure. If you
do not want automatic diagnostics you should use the "send_event()" method directly.
The third argument "\@on_fail") is an optional set of diagnostics to be sent in the
event of a test failure. Unlike with "fail()" these diagnostics must be plain strings,
data structures are not supported.
$event = $ctx->note($message)
Send an Test2::Event::Note. This event prints a message to STDOUT.
$event = $ctx->diag($message)
Send an Test2::Event::Diag. This event prints a message to STDERR.
$event = $ctx->plan($max)
$event = $ctx->plan(0, 'SKIP', $reason)
This can be used to send an Test2::Event::Plan event. This event usually takes either
a number of tests you expect to run. Optionally you can set the expected count to 0
and give the 'SKIP' directive with a reason to cause all tests to be skipped.
$event = $ctx->skip($name, $reason);
Send an Test2::Event::Skip event.
$event = $ctx->bail($reason)
This sends an Test2::Event::Bail event. This event will completely terminate all
testing.
$event = $ctx->send_ev2(%facets)
This lets you build and send a V2 event directly from facets. The event is returned
after it is sent.
This example sends a single assertion, a note (comment for stdout in Test::Builder
talk) and sets the plan to 1.
my $event = $ctx->send_event(
plan => {count => 1},
assert => {pass => 1, details => "A passing assert"},
info => [{tag => 'NOTE', details => "This is a note"}],
);
$event = $ctx->build_e2(%facets)
This is the same as "send_ev2()", except it builds and returns the event without
sending it.
$event = $ctx->send_ev2_and_release($Type, %parameters)
This is a combination of "send_ev2()" and "release()".
sub shorthand {
my $ctx = context();
return $ctx->send_ev2_and_release(assert => {pass => 1, details => 'foo'});
}
sub longform {
my $ctx = context();
my $event = $ctx->send_ev2(assert => {pass => 1, details => 'foo'});
$ctx->release;
return $event;
}
$event = $ctx->send_event($Type, %parameters)
It is better to use send_ev2() in new code.
This lets you build and send an event of any type. The $Type argument should be the
event package name with "Test2::Event::" left off, or a fully qualified package name
prefixed with a '+'. The event is returned after it is sent.
my $event = $ctx->send_event('Ok', ...);
or
my $event = $ctx->send_event('+Test2::Event::Ok', ...);
$event = $ctx->build_event($Type, %parameters)
It is better to use build_ev2() in new code.
This is the same as "send_event()", except it builds and returns the event without
sending it.
$event = $ctx->send_event_and_release($Type, %parameters)
It is better to use send_ev2_and_release() in new code.
This is a combination of "send_event()" and "release()".
sub shorthand {
my $ctx = context();
return $ctx->send_event_and_release(Pass => { name => 'foo' });
}
sub longform {
my $ctx = context();
my $event = $ctx->send_event(Pass => { name => 'foo' });
$ctx->release;
return $event;
}
HOOKS
There are 2 types of hooks, init hooks, and release hooks. As the names suggest, these
hooks are triggered when contexts are created or released.
INIT HOOKS
These are called whenever a context is initialized. That means when a new instance is
created. These hooks are NOT called every time something requests a context, just when a
new one is created.
GLOBAL
This is how you add a global init callback. Global callbacks happen for every context for
any hub or stack.
Test2::API::test2_add_callback_context_init(sub {
my $ctx = shift;
...
});
PER HUB
This is how you add an init callback for all contexts created for a given hub. These
callbacks will not run for other hubs.
$hub->add_context_init(sub {
my $ctx = shift;
...
});
PER CONTEXT
This is how you specify an init hook that will only run if your call to "context()"
generates a new context. The callback will be ignored if "context()" is returning an
existing context.
my $ctx = context(on_init => sub {
my $ctx = shift;
...
});
RELEASE HOOKS
These are called whenever a context is released. That means when the last reference to the
instance is about to be destroyed. These hooks are NOT called every time "$ctx->release"
is called.
GLOBAL
This is how you add a global release callback. Global callbacks happen for every context
for any hub or stack.
Test2::API::test2_add_callback_context_release(sub {
my $ctx = shift;
...
});
PER HUB
This is how you add a release callback for all contexts created for a given hub. These
callbacks will not run for other hubs.
$hub->add_context_release(sub {
my $ctx = shift;
...
});
PER CONTEXT
This is how you add release callbacks directly to a context. The callback will ALWAYS be
added to the context that gets returned, it does not matter if a new one is generated, or
if an existing one is returned.
my $ctx = context(on_release => sub {
my $ctx = shift;
...
});
THIRD PARTY META-DATA
This object consumes Test2::Util::ExternalMeta which provides a consistent way for you to
attach meta-data to instances of this class. This is useful for tools, plugins, and other
extensions.
SOURCE
The source code repository for Test2 can be found at
http://github.com/Test-More/test-more/.
MAINTAINERS
Chad Granum <exodist@cpan.org>
AUTHORS
Chad Granum <exodist@cpan.org>
Kent Fredric <kentnl@cpan.org>
COPYRIGHT
Copyright 2020 Chad Granum <exodist@cpan.org>.
This program is free software; you can redistribute it and/or modify it under the same
terms as Perl itself.
See http://dev.perl.org/licenses/