[TestNG] Fix concurrent modification of events #1919
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When a TestNG suite with `parallel="methods"` is executed TestNG will invoke all `@DataProvider` annotated methods. Because these data providers also emit the `TestRunStarted` event this event is emitted twice concurrently. These events collide in the `CanonicalOrderEventPublisher` resulting in a concurrent modification that inserts a null element rather then either of the events. By moving the start of the test execution to the constructor we ensure that test execution is always started serially. Additionally this ensures that it is impossible to emit a `TestRunFinished` event without also emitting a `TestRunStarted` event. This comes at the cost of starting the execution as soon as the `@BeforeClass` method is invoked. This will result in some apparent overhead as `TestNG` is still preparing for execution. Fixes: #1917
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When a TestNG suite with
parallel="methods"is executed TestNG will invokeall
@DataProviderannotated methods. Because these data providers also emitthe
TestRunStartedevent this event is emitted twice concurrently. Theseevents collide in the
CanonicalOrderEventPublisherresulting in a concurrentmodification that inserts a null element rather then either of the events.
By moving the start of the test execution to the constructor we ensure that
test execution is always started serially. Additionally this ensures that it is
impossible to emit a
TestRunFinishedevent without also emitting aTestRunStartedevent.This comes at the cost of starting the execution as soon as the
@BeforeClassmethod is invoked. This will result in some apparent overhead as TestNG is
still preparing for execution.
Fixes: #1917
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