45 lines
1.5 KiB
Markdown
45 lines
1.5 KiB
Markdown
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<a id="top"></a>
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# Event Listeners
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An event listener is a bit like a reporter, in that it responds to various
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reporter events in Catch2, but it is not expected to write any output.
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Instead, an event listener performs actions within the test process, such
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as performing global initialization (e.g. of a C library), or cleaning out
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in-memory logs if they are not needed (the test case passed).
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Unlike reporters, each registered event listener is always active. Event
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listeners are always notified before reporter(s).
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To write your own event listener, you should derive from `Catch::TestEventListenerBase`,
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as it provides empty stubs for all reporter events, allowing you to
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only override events you care for. Afterwards you have to register it
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with Catch2 using `CATCH_REGISTER_LISTENER` macro, so that Catch2 knows
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about it and instantiates it before running tests.
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Example event listener:
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```cpp
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#include <catch2/reporters/catch_reporter_event_listener.hpp>
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#include <catch2/reporters/catch_reporter_registrars.hpp>
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class testRunListener : public Catch::EventListenerBase {
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public:
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using Catch::EventListenerBase::EventListenerBase;
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void testRunStarting(Catch::TestRunInfo const&) override {
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lib_foo_init();
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}
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};
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CATCH_REGISTER_LISTENER(testRunListener)
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```
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_Note that you should not use any assertion macros within a Listener!_
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[You can find the list of events that the listeners can react to on its
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own page](reporter-events.md#top).
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---
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[Home](Readme.md#top)
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