Test2::API(3perl) Perl Programmers Reference Guide Test2::API(3perl)
NAME
Test2::API - Primary interface for writing Test2 based testing tools.
***INTERNALS NOTE***
The internals of this package are subject to change at any time! The
public methods provided will not change in backwards-incompatible ways
(once there is a stable release), but the underlying implementation
details might. Do not break encapsulation here!
Currently the implementation is to create a single instance of the
Test2::API::Instance Object. All class methods defer to the single
instance. There is no public access to the singleton, and that is
intentional. The class methods provided by this package provide the
only functionality publicly exposed.
This is done primarily to avoid the problems Test::Builder had by
exposing its singleton. We do not want anyone to replace this singleton,
rebless it, or directly muck with its internals. If you need to do
something and cannot because of the restrictions placed here, then
please report it as an issue. If possible, we will create a way for you
to implement your functionality without exposing things that should not
be exposed.
DESCRIPTION
This package exports all the functions necessary to write and/or verify
testing tools. Using these building blocks you can begin writing test
tools very quickly. You are also provided with tools that help you to
test the tools you write.
SYNOPSIS
WRITING A TOOL
The context() method is your primary interface into the Test2 framework.
package My::Ok;
use Test2::API qw/context/;
our @EXPORT = qw/my_ok/;
use base 'Exporter';
# Just like ok() from Test::More
sub my_ok($;$) {
my ($bool, $name) = @_;
my $ctx = context(); # Get a context
$ctx->ok($bool, $name);
$ctx->release; # Release the context
return $bool;
}
See Test2::API::Context for a list of methods available on the context
object.
TESTING YOUR TOOLS
The "intercept { ... }" tool lets you temporarily intercept all events
generated by the test system:
use Test2::API qw/intercept/;
use My::Ok qw/my_ok/;
my $events = intercept {
# These events are not displayed
my_ok(1, "pass");
my_ok(0, "fail");
};
As of version 1.302178 this now returns an arrayref that is also an
instance of Test2::API::InterceptResult. See the
Test2::API::InterceptResult documentation for details on how to best use
it.
OTHER API FUNCTIONS
use Test2::API qw{
test2_init_done
test2_stack
test2_set_is_end
test2_get_is_end
test2_ipc
test2_formatter_set
test2_formatter
test2_is_testing_done
};
my $init = test2_init_done();
my $stack = test2_stack();
my $ipc = test2_ipc();
test2_formatter_set($FORMATTER)
my $formatter = test2_formatter();
... And others ...
MAIN API EXPORTS
All exports are optional. You must specify subs to import.
use Test2::API qw/context intercept run_subtest/;
This is the list of exports that are most commonly needed. If you are
simply writing a tool, then this is probably all you need. If you need
something and you cannot find it here, then you can also look at "OTHER
API EXPORTS".
These exports lack the 'test2_' prefix because of how important/common
they are. Exports in the "OTHER API EXPORTS" section have the 'test2_'
prefix to ensure they stand out.
context(...)
Usage:
$ctx = context()
$ctx = context(%params)
The context() function will always return the current context. If there
is already a context active, it will be returned. If there is not an
active context, one will be generated. When a context is generated it
will default to using the file and line number where the currently
running sub was called from.
Please see "CRITICAL DETAILS" in Test2::API::Context for important rules
about what you can and cannot do with a context once it is obtained.
Note This function will throw an exception if you ignore the context
object it returns.
Note On perls 5.14+ a depth check is used to ensure there are no context
leaks. This cannot be safely done on older perls due to
<https://rt.perl.org/Public/Bug/Display.html?id=127774> You can
forcefully enable it either by setting "$ENV{T2_CHECK_DEPTH} = 1" or
"$Test2::API::DO_DEPTH_CHECK = 1" BEFORE loading Test2::API.
OPTIONAL PARAMETERS
All parameters to "context" are optional.
level => $int
If you must obtain a context in a sub deeper than your entry point
you can use this to tell it how many EXTRA stack frames to look
back. If this option is not provided the default of 0 is used.
sub third_party_tool {
my $sub = shift;
... # Does not obtain a context
$sub->();
...
}
third_party_tool(sub {
my $ctx = context(level => 1);
...
$ctx->release;
});
wrapped => $int
Use this if you need to write your own tool that wraps a call to
context() with the intent that it should return a context object.
sub my_context {
my %params = ( wrapped => 0, @_ );
$params{wrapped}++;
my $ctx = context(%params);
...
return $ctx;
}
sub my_tool {
my $ctx = my_context();
...
$ctx->release;
}
If you do not do this, then tools you call that also check for a
context will notice that the context they grabbed was created at the
same stack depth, which will trigger protective measures that warn
you and destroy the existing context.
stack => $stack
Normally context() looks at the global hub stack. If you are
maintaining your own Test2::API::Stack instance you may pass it in
to be used instead of the global one.
hub => $hub
Use this parameter if you want to obtain the context for a specific
hub instead of whatever one happens to be at the top of the stack.
on_init => sub { ... }
This lets you provide a callback sub that will be called ONLY if
your call to context() generated a new context. The callback WILL
NOT be called if context() is returning an existing context. The
only argument passed into the callback will be the context object
itself.
sub foo {
my $ctx = context(on_init => sub { 'will run' });
my $inner = sub {
# This callback is not run since we are getting the existing
# context from our parent sub.
my $ctx = context(on_init => sub { 'will NOT run' });
$ctx->release;
}
$inner->();
$ctx->release;
}
on_release => sub { ... }
This lets you provide a callback sub that will be called when the
context instance is released. This callback will be added to the
returned context even if an existing context is returned. If
multiple calls to context add callbacks, then all will be called in
reverse order when the context is finally released.
sub foo {
my $ctx = context(on_release => sub { 'will run second' });
my $inner = sub {
my $ctx = context(on_release => sub { 'will run first' });
# Neither callback runs on this release
$ctx->release;
}
$inner->();
# Both callbacks run here.
$ctx->release;
}
release($;$)
Usage:
release $ctx;
release $ctx, ...;
This is intended as a shortcut that lets you release your context and
return a value in one statement. This function will get your context,
and an optional return value. It will release your context, then return
your value. Scalar context is always assumed.
sub tool {
my $ctx = context();
...
return release $ctx, 1;
}
This tool is most useful when you want to return the value you get from
calling a function that needs to see the current context:
my $ctx = context();
my $out = some_tool(...);
$ctx->release;
return $out;
We can combine the last 3 lines of the above like so:
my $ctx = context();
release $ctx, some_tool(...);
context_do(&;@)
Usage:
sub my_tool {
context_do {
my $ctx = shift;
my (@args) = @_;
$ctx->ok(1, "pass");
...
# No need to call $ctx->release, done for you on scope exit.
} @_;
}
Using this inside your test tool takes care of a lot of boilerplate for
you. It will ensure a context is acquired. It will capture and rethrow
any exception. It will ensure the context is released when you are done.
It preserves the subroutine call context (list, scalar, void).
This is the safest way to write a test tool. The only two downsides to
this are a slight performance decrease, and some extra indentation in
your source. If the indentation is a problem for you then you can take a
peek at the next section.
no_context(&;$)
Usage:
no_context { ... };
no_context { ... } $hid;
sub my_tool(&) {
my $code = shift;
my $ctx = context();
...
no_context {
# Things in here will not see our current context, they get a new
# one.
$code->();
};
...
$ctx->release;
};
This tool will hide a context for the provided block of code. This means
any tools run inside the block will get a completely new context if they
acquire one. The new context will be inherited by tools nested below the
one that acquired it.
This will normally hide the current context for the top hub. If you need
to hide the context for a different hub you can pass in the optional
$hid parameter.
intercept(&)
Usage:
my $events = intercept {
ok(1, "pass");
ok(0, "fail");
...
};
This function takes a codeblock as its only argument, and it has a
prototype. It will execute the codeblock, intercepting any generated
events in the process. It will return an array reference with all the
generated event objects. All events should be subclasses of
Test2::Event.
As of version 1.302178 the events array that is returned is blssed as an
Test2::API::InterceptResult instance. Test2::API::InterceptResult
Provides a helpful interface for filtering and/or inspecting the events
list overall, or individual events within the list.
This is intended to help you test your test code. This is not intended
for people simply writing tests.
run_subtest(...)
Usage:
run_subtest($NAME, \&CODE, $BUFFERED, @ARGS)
# or
run_subtest($NAME, \&CODE, \%PARAMS, @ARGS)
This will run the provided codeblock with the args in @args. This
codeblock will be run as a subtest. A subtest is an isolated test state
that is condensed into a single Test2::Event::Subtest event, which
contains all events generated inside the subtest.
ARGUMENTS:
$NAME
The name of the subtest.
\&CODE
The code to run inside the subtest.
$BUFFERED or \%PARAMS
If this is a simple scalar then it will be treated as a boolean for
the 'buffered' setting. If this is a hash reference then it will be
used as a parameters hash. The param hash will be used for hub
construction (with the specified keys removed).
Keys that are removed and used by run_subtest:
'buffered' => $bool
Toggle buffered status.
'inherit_trace' => $bool
Normally the subtest hub is pushed and the sub is allowed to
generate its own root context for the hub. When this setting is
turned on a root context will be created for the hub that shares
the same trace as the current context.
Set this to true if your tool is producing subtests without
user-specified subs.
'no_fork' => $bool
Defaults to off. Normally forking inside a subtest will actually
fork the subtest, resulting in 2 final subtest events. This
parameter will turn off that behavior, only the original
process/thread will return a final subtest event.
@ARGS
Any extra arguments you want passed into the subtest code.
BUFFERED VS UNBUFFERED (OR STREAMED)
Normally all events inside and outside a subtest are sent to the
formatter immediately by the hub. Sometimes it is desirable to hold off
sending events within a subtest until the subtest is complete. This
usually depends on the formatter being used.
Things not affected by this flag
In both cases events are generated and stored in an array. This
array is eventually used to populate the "subevents" attribute on
the Test2::Event::Subtest event that is generated at the end of the
subtest. This flag has no effect on this part, it always happens.
At the end of the subtest, the final Test2::Event::Subtest event is
sent to the formatter.
Things that are affected by this flag
The "buffered" attribute of the Test2::Event::Subtest event will be
set to the value of this flag. This means any formatter, listener,
etc which looks at the event will know if it was buffered.
Things that are formatter dependent
Events within a buffered subtest may or may not be sent to the
formatter as they happen. If a formatter fails to specify then the
default is to NOT SEND the events as they are generated, instead the
formatter can pull them from the "subevents" attribute.
A formatter can specify by implementing the hide_buffered() method.
If this method returns true then events generated inside a buffered
subtest will not be sent independently of the final subtest event.
An example of how this is used is the Test2::Formatter::TAP formatter.
For unbuffered subtests the events are rendered as they are generated.
At the end of the subtest, the final subtest event is rendered, but the
"subevents" attribute is ignored. For buffered subtests the opposite
occurs, the events are NOT rendered as they are generated, instead the
"subevents" attribute is used to render them all at once. This is useful
when running subtests tests in parallel, since without it the output
from subtests would be interleaved together.
OTHER API EXPORTS
Exports in this section are not commonly needed. These all have the
'test2_' prefix to help ensure they stand out. You should look at the
"MAIN API EXPORTS" section before looking here. This section is one
where "Great power comes with great responsibility". It is possible to
break things badly if you are not careful with these.
All exports are optional. You need to list which ones you want at import
time:
use Test2::API qw/test2_init_done .../;
STATUS AND INITIALIZATION STATE
These provide access to internal state and object instances.
$bool = test2_init_done()
This will return true if the stack and IPC instances have already
been initialized. It will return false if they have not. Init
happens as late as possible. It happens as soon as a tool requests
the IPC instance, the formatter, or the stack.
$bool = test2_load_done()
This will simply return the boolean value of the loaded flag. If
Test2 has finished loading this will be true, otherwise false.
Loading is considered complete the first time a tool requests a
context.
test2_set_is_end()
test2_set_is_end($bool)
This is used to toggle Test2's belief that the END phase has already
started. With no arguments this will set it to true. With arguments
it will set it to the first argument's value.
This is used to prevent the use of caller() in END blocks which can
cause segfaults. This is only necessary in some persistent
environments that may have multiple END phases.
$bool = test2_get_is_end()
Check if Test2 believes it is the END phase.
$stack = test2_stack()
This will return the global Test2::API::Stack instance. If this has
not yet been initialized it will be initialized now.
$bool = test2_is_testing_done()
This will return true if testing is complete and no other events
should be sent. This is useful in things like warning handlers where
you might want to turn warnings into events, but need them to start
acting like normal warnings when testing is done.
$SIG{__WARN__} = sub {
my ($warning) = @_;
if (test2_is_testing_done()) {
warn @_;
}
else {
my $ctx = context();
...
$ctx->release
}
}
test2_ipc_disable
Disable IPC.
$bool = test2_ipc_disabled
Check if IPC is disabled.
test2_ipc_wait_enable()
test2_ipc_wait_disable()
$bool = test2_ipc_wait_enabled()
These can be used to turn IPC waiting on and off, or check the
current value of the flag.
Waiting is turned on by default. Waiting will cause the parent
process/thread to wait until all child processes and threads are
finished before exiting. You will almost never want to turn this
off.
$bool = test2_no_wait()
test2_no_wait($bool)
DISCOURAGED: This is a confusing interface, it is better to use
test2_ipc_wait_enable(), test2_ipc_wait_disable() and
test2_ipc_wait_enabled().
This can be used to get/set the no_wait status. Waiting is turned on
by default. Waiting will cause the parent process/thread to wait
until all child processes and threads are finished before exiting.
You will almost never want to turn this off.
$fh = test2_stdout()
$fh = test2_stderr()
These functions return the filehandles that test output should be
written to. They are primarily useful when writing a custom
formatter and code that turns events into actual output (TAP, etc.).
They will return a dupe of the original filehandles that formatted
output can be sent to regardless of whatever state the currently
running test may have left STDOUT and STDERR in.
test2_reset_io()
Re-dupe the internal filehandles returned by test2_stdout() and
test2_stderr() from the current STDOUT and STDERR. You shouldn't
need to do this except in very peculiar situations (for example,
you're testing a new formatter and you need control over where the
formatter is sending its output.)
BEHAVIOR HOOKS
These are hooks that allow you to add custom behavior to actions taken
by Test2 and tools built on top of it.
test2_add_callback_exit(sub { ... })
This can be used to add a callback that is called after all testing
is done. This is too late to add additional results, the main use of
this callback is to set the exit code.
test2_add_callback_exit(
sub {
my ($context, $exit, \$new_exit) = @_;
...
}
);
The $context passed in will be an instance of Test2::API::Context.
The $exit argument will be the original exit code before anything
modified it. $$new_exit is a reference to the new exit code. You
may modify this to change the exit code. Please note that $$new_exit
may already be different from $exit
test2_add_callback_post_load(sub { ... })
Add a callback that will be called when Test2 is finished loading.
This means the callback will be run once, the first time a context
is obtained. If Test2 has already finished loading then the
callback will be run immediately.
test2_add_callback_testing_done(sub { ... })
This adds your coderef as a follow-up to the root hub after Test2 is
finished loading.
This is essentially a helper to do the following:
test2_add_callback_post_load(sub {
my $stack = test2_stack();
$stack->top; # Ensure we have a hub
my ($hub) = Test2::API::test2_stack->all;
$hub->set_active(1);
$hub->follow_up(sub { ... }); # <-- Your coderef here
});
test2_add_callback_context_acquire(sub { ... })
Add a callback that will be called every time someone tries to
acquire a context. This will be called on EVERY call to context().
It gets a single argument, a reference to the hash of parameters
being used the construct the context. This is your chance to change
the parameters by directly altering the hash.
test2_add_callback_context_acquire(sub {
my $params = shift;
$params->{level}++;
});
This is a very scary API function. Please do not use this unless you
need to. This is here for Test::Builder and backwards
compatibility. This has you directly manipulate the hash instead of
returning a new one for performance reasons.
test2_add_callback_context_init(sub { ... })
Add a callback that will be called every time a new context is
created. The callback will receive the newly created context as its
only argument.
test2_add_callback_context_release(sub { ... })
Add a callback that will be called every time a context is released.
The callback will receive the released context as its only argument.
test2_add_callback_pre_subtest(sub { ... })
Add a callback that will be called every time a subtest is going to
be run. The callback will receive the subtest name, coderef, and any
arguments.
@list = test2_list_context_acquire_callbacks()
Return all the context acquire callback references.
@list = test2_list_context_init_callbacks()
Returns all the context init callback references.
@list = test2_list_context_release_callbacks()
Returns all the context release callback references.
@list = test2_list_exit_callbacks()
Returns all the exit callback references.
@list = test2_list_post_load_callbacks()
Returns all the post load callback references.
@list = test2_list_pre_subtest_callbacks()
Returns all the pre-subtest callback references.
test2_add_uuid_via(sub { ... })
$sub = test2_add_uuid_via()
This allows you to provide a UUID generator. If provided UUIDs will
be attached to all events, hubs, and contexts. This is useful for
storing, tracking, and linking these objects.
The sub you provide should always return a unique identifier. Most
things will expect a proper UUID string, however nothing in
Test2::API enforces this.
The sub will receive exactly 1 argument, the type of thing being
tagged 'context', 'hub', or 'event'. In the future additional things
may be tagged, in which case new strings will be passed in. These
are purely informative, you can (and usually should) ignore them.
IPC AND CONCURRENCY
These let you access, or specify, the IPC system internals.
$bool = test2_has_ipc()
Check if IPC is enabled.
$ipc = test2_ipc()
This will return the global Test2::IPC::Driver instance. If this has
not yet been initialized it will be initialized now.
test2_ipc_add_driver($DRIVER)
Add an IPC driver to the list. This will add the driver to the start
of the list.
@drivers = test2_ipc_drivers()
Get the list of IPC drivers.
$bool = test2_ipc_polling()
Check if polling is enabled.
test2_ipc_enable_polling()
Turn on polling. This will cull events from other processes and
threads every time a context is created.
test2_ipc_disable_polling()
Turn off IPC polling.
test2_ipc_enable_shm()
Legacy, this is currently a no-op that returns 0;
test2_ipc_set_pending($uniq_val)
Tell other processes and events that an event is pending. $uniq_val
should be a unique value no other thread/process will generate.
Note: After calling this test2_ipc_get_pending() will return 1. This
is intentional, and not avoidable.
$pending = test2_ipc_get_pending()
This returns -1 if there is no way to check (assume yes)
This returns 0 if there are (most likely) no pending events.
This returns 1 if there are (likely) pending events. Upon return it
will reset, nothing else will be able to see that there were pending
events.
$timeout = test2_ipc_get_timeout()
test2_ipc_set_timeout($timeout)
Get/Set the timeout value for the IPC system. This timeout is how
long the IPC system will wait for child processes and threads to
finish before aborting.
The default value is 30 seconds.
MANAGING FORMATTERS
These let you access, or specify, the formatters that can/should be
used.
$formatter = test2_formatter
This will return the global formatter class. This is not an
instance. By default the formatter is set to Test2::Formatter::TAP.
You can override this default using the "T2_FORMATTER" environment
variable.
Normally 'Test2::Formatter::' is prefixed to the value in the
environment variable:
$ T2_FORMATTER='TAP' perl test.t # Use the Test2::Formatter::TAP formatter
$ T2_FORMATTER='Foo' perl test.t # Use the Test2::Formatter::Foo formatter
If you want to specify a full module name you use the '+' prefix:
$ T2_FORMATTER='+Foo::Bar' perl test.t # Use the Foo::Bar formatter
test2_formatter_set($class_or_instance)
Set the global formatter class. This can only be set once. Note:
This will override anything specified in the 'T2_FORMATTER'
environment variable.
@formatters = test2_formatters()
Get a list of all loaded formatters.
test2_formatter_add($class_or_instance)
Add a formatter to the list. Last formatter added is used at
initialization. If this is called after initialization a warning
will be issued.
TIME STAMPS
You can enable or disable timestamps in trace facets. They are disabled
by default for compatibility and performance reasons.
test2_enable_trace_stamps()
Enable stamps in traces.
test2_disable_trace_stamps()
Disable stamps in traces.
$bool = test2_trace_stamps_enabled()
Check status of trace stamps.
OTHER EXAMPLES
See the "/Examples/" directory included in this distribution.
SEE ALSO
Test2::API::Context - Detailed documentation of the context object.
Test2::IPC - The IPC system used for threading/fork support.
Test2::Formatter - Formatters such as TAP live here.
Test2::Event - Events live in this namespace.
Test2::Hub - All events eventually funnel through a hub. Custom hubs are
how intercept() and run_subtest() are implemented.
MAGIC
This package has an END block. This END block is responsible for setting
the exit code based on the test results. This end block also calls the
callbacks that can be added to this package.
SOURCE
The source code repository for Test2 can be found at
<https://github.com/Test-More/test-more/>.
MAINTAINERS
Chad Granum <exodist@cpan.org>
AUTHORS
Chad Granum <exodist@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 <https://dev.perl.org/licenses/>
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