Test2::Manual::Anatomy::Hubs(3) User Contributed Perl Documentation
NAME
Test2::Manual::Anatomy::Hubs - Internals documentation for the hub
stack, and hubs.
DESCRIPTION
This document describes the hub stack, and the hubs it contains. It
explains why we have a stack, and when to add/remove hubs from it.
WHAT IS A HUB?
Test2 is an event system, tools generate events, those events are then
processed to modify the testing state (number of tests, number of
failures, etc). The hub is responsible for receiving and processing
events to record the change in state. All events should eventually
reach a destination hub.
The base hub is Test2::Hub. All hub classes should inherit from the
base hub class. The base hub class provides several hooks that allow
you to monitor or modify events. Hubs are also responsible for
forwarding events to the output formatter.
WHY DO WE HAVE A HUB STACK?
There are cases where it makes sense to have more than one hub:
subtests
In Test2 subtests are implemented using the hub stack. When you
start a subtest a new Test2::Hub::Subtest instance is created and
pushed to the stack. Once this is done all calls to
"Test2::API::context" will find the new hub and send all events to
it. When the subtest tool is complete it will remove the new hub,
and send a final subtest event to the parent hub.
testing your test tools
Test2::API::intercept() is implemented using the hub stack. The
Test2::API::intercept() function will add an
Test2::Hub::Interceptor instance to the stack, any calls to
Test2::API::context() will find the new hub, and send it all
events. The intercept hub is special in that is has no connection
to the parent hub, and usually does not have a formatter.
WHEN SHOULD I ADD A HUB TO THE STACK?
Any time you want to intercept or block events from affecting the test
state. Adding a new hub is essentially a way to create a sandbox where
you have absolute control over what events do. Adding a new hub insures
that the main test state will not be affected.
WHERE IS THE STACK?
The stack is an instance of Test2::API::Stack. You can access the
global hub stack using "Test2::API::test2_stack".
WHAT ABOUT THE ROOT HUB?
The root hub is created automatically as needed. A call to
"Test2::API::test2_stack->top()" will create the root hub if it does
not already exist.
HOW DO HUBS HANDLE IPC?
If the IPC system (Test2::IPC) was not loaded, then IPC is not handled
at all. Forking or creating new threads without the IPC system can
cause unexpected problems.
All hubs track the PID and Thread ID that was current when they were
created. If an event is sent to a hub in a new process/thread the hub
will detect this and try to forward the event along to the correct
process/thread. This is accomplished using the IPC system.
SEE ALSO
Test2::Manual(3) - Primary index of the manual.
SOURCE
The source code repository for Test2-Manual 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 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/
perl v5.34.3 2025-03-30 Test2::Manual::Anatomy::Hubs(3)
test-simple 1.302.210 - Generated Tue Apr 1 18:37:48 CDT 2025