[LUCENE-3492] Extract a generic framework for running randomized tests.

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Component/s: general/test
• Lucene Fields: New
• Assignee: Dawid Weiss
• Reporter: Dawid Weiss
• Created: 06/Oct/11 10:54
• Updated: 28/Aug/22 12:59
• Resolved: 14/Feb/12 15:32

Description

The work on this issue is temporarily at github (lots of experiments and tweaking):
https://github.com/carrotsearch/randomizedtesting
Or directly: git clone git://github.com/carrotsearch/randomizedtesting.git

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RandomizedRunner is a JUnit runner, so it is capable of running @Test-annotated test cases. It
respects regular lifecycle hooks such as @Before, @After, @BeforeClass or @AfterClass, but it
also adds the following:

Randomized, but repeatable execution and infrastructure for dealing with randomness:

• uses pseudo-randomness (so that a given run can be repeated if given the same starting seed)
  for many things called "random" below,
• randomly shuffles test methods to ensure they don't depend on each other,
• randomly shuffles hooks (within a given class) to ensure they don't depend on each other,
• base class RandomizedTest provides a number of methods for generating random numbers, strings
  and picking random objects from collections (again, this is fully repeatable given the
  initial seed if there are no race conditions),
• the runner provides infrastructure to augment stack traces with information about the initial
  seeds used for running the test, so that it can be repeated (or it can be determined that
  the test is not repeatable – this indicates a problem with the test case itself).

Thread control:

• any threads created as part of a test case are assigned the same initial random seed
  (repeatability),
• tracks and attempts to terminate any Threads that are created and not terminated inside
  a test case (not cleaning up causes a test failure),
• tracks and attempts to terminate test cases that run for too long (default timeout: 60 seconds,
  adjustable using global property or annotations),

Improved validation and lifecycle support:

• RandomizedRunner uses relaxed contracts of hook methods' accessibility (hook methods can be
  private). This helps in avoiding problems with method shadowing (static hooks) or overrides
  that require tedious super.() chaining). Private hooks are always executed and don't affect
  subclasses in any way, period.
• @Listeners annotation on a test class allows it to hook into the execution progress and listen
  to events.
• @Validators annotation allows a test class to provide custom validation strategies
  (project-specific). For example a base class can request specific test case naming strategy
  (or reject JUnit3-like methods, for instance).
• RandomizedRunner does not "chain" or "suppress" exceptions happening during execution of
  a test case (including hooks). All exceptions are reported as soon as they happened and multiple
  failure reports can occur. Most environments we know of then display these failures sequentially
  allowing a clearer understanding of what actually happened first.

Issue Links

• relates to: LUCENE-3784 Switching tests infrastructure to randomizedtesting.*
• relates to: LUCENE-3489 Refactor test classes that use assumeFalse(codec != SimpleText, Memory) to use new annotation and move the expensive methods to separate classes