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/*
* Copyright 2001-2013 Artima, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.scalatest
import time.Span
/**
* Provides methods that can be used in withFixture implementations to retry tests in various scenarios.
*
*
* Trait Retries is intended to help you deal with “flickers”—tests that usually pass, but
* occasionally fail. The best way to deal with such tests is to fix them so they always pass. Sometimes, however, this is
* not practical. In such cases, flickers can waste your time by forcing you to investigate test failures that turn
* out to be flickers. Or worse, like the boy who cried wolf, the flickers may train you an your colleagues to not pay attention
* to failures such that you don't notice real problems, at least not in a timely manner.
*
*
*
* Trait Retries offers methods that will retry a failed and/or canceled test once, on the same thread,
* with or without a delay. These methods take a block that results in Outcome,
* and are intended to be used in withFixture methods. You should be very selective about which tests you
* retry, retrying those for which you have good evidence to conclude they are flickers. Thus it is recommended you
* only retry tests that are tagged with Retryable, and only tag tests as such once they have flickered
* consistently for a while, and only after you invested a reasonable effort into fixing them properly.
*
*
*
* Here's an example showing how you might use Retries:
*
*
*
* package org.scalatest.examples.tagobjects.retryable
*
* import org.scalatest._
* import tagobjects.Retryable
*
* class SetSpec extends FlatSpec with Retries {
*
* override def withFixture(test: NoArgTest) = {
* if (isRetryable(test))
* withRetry { super.withFixture(test) }
* else
* super.withFixture(test)
* }
*
* "An empty Set" should "have size 0" taggedAs(Retryable) in {
* assert(Set.empty.size === 0)
* }
* }
*
*/
trait Retries {
/**
* Retries the given block immediately (with no delay) if the Outcome of executing
* the block is either Failed or Canceled.
*
*
* The behavior of this method is defined in the table below. The first two rows show the main "retry" behavior: if
* executing the block initially fails, and on retry it succeeds, the result is Canceled. The purpose of this is
* to deal with "flickering" tests by downgrading a failure that succeeds on retry to a cancelation.
* Or, if executing the block initially results in Canceled, and on retry it succeeds, the result
* is Succeeded. The purpose of this is to deal with tests that intermittently cancel by ignoring a cancelation that
* succeeds on retry.
*
*
*
* In the table below, if the “Retry Outcome” has just a dash, the block is not retried.
* Otherwise, the block is retried on the same thread, with no delay.
*
*
*
* First Outcome Retry Outcome Result
*
* Failed
*
*
* Succeeded
*
*
* Canceled (the Succeeded and Failed are
* discarded; the exception from the Failed is the cause of the exception in the Canceled)
*
*
*
*
* Canceled
*
*
* Succeeded
*
*
* Succeeded (the Canceled is discarded)
*
*
*
*
* Succeeded
*
*
* —
*
*
* Succeeded (no retry)
*
*
*
*
* Pending
*
*
* —
*
*
* Pending (no retry)
*
*
*
*
* Failed
*
*
* Failed
*
*
* the first Failed (the second Failed is discarded)
*
*
*
*
* Failed
*
*
* Pending
*
*
* the Failed (the Pending is discarded)
*
*
*
*
* Failed
*
*
* Canceled
*
*
* the Failed (the Canceled is discarded)
*
*
*
*
* Canceled
*
*
* Canceled
*
*
* the first Canceled (the second Canceled is discarded)
*
*
*
*
* Canceled
*
*
* Pending
*
*
* the Canceled (the Pending is discarded)
*
*
*
*
* Canceled
*
*
* Failed
*
*
* the Failed (the Canceled is discarded)
*
*
*
*
* @param blk the block to execute and potentially retry
*/
def withRetry(blk: => Outcome): Outcome = withRetry(Span.Zero)(blk)
/**
* Retries the given block with a given delay if the Outcome of executing
* the block is either Failed or Canceled.
*
*
* The behavior of this method is defined in the table below. The first two rows show the main "retry" behavior: if
* executing the block initially fails, and on retry it succeeds, the result is Canceled. The purpose of this is
* to deal with "flickering" tests by downgrading a failure that succeeds on retry
* to a cancelation.
* Or, if executing the block initially results in Canceled, and on retry it succeeds, the result
* is Succeeded. The purpose of this is to deal with tests that intermittently cancel by ignoring a cancelation that
* succeeds on retry.
*
*
*
* In the table below, if the “Retry Outcome” has just a dash, the block is not retried.
* Otherwise, the block is retried on the same thread, after sleeping the given delay.
*
*
*
* First Outcome Retry Outcome Result
*
* Failed
*
*
* Succeeded
*
*
* Canceled (the Succeeded and Failed are
* discarded; the exception from the Failed is the cause of the exception in the Canceled)
*
*
*
*
* Canceled
*
*
* Succeeded
*
*
* Succeeded (the Canceled is discarded)
*
*
*
*
* Succeeded
*
*
* —
*
*
* Succeeded (no retry)
*
*
*
*
* Pending
*
*
* —
*
*
* Pending (no retry)
*
*
*
*
* Failed
*
*
* Failed
*
*
* the first Failed (the second Failed is discarded)
*
*
*
*
* Failed
*
*
* Pending
*
*
* the Failed (the Pending is discarded)
*
*
*
*
* Failed
*
*
* Canceled
*
*
* the Failed (the Canceled is discarded)
*
*
*
*
* Canceled
*
*
* Canceled
*
*
* the first Canceled (the second Canceled is discarded)
*
*
*
*
* Canceled
*
*
* Pending
*
*
* the Canceled (the Pending is discarded)
*
*
*
*
* Canceled
*
*
* Failed
*
*
* the Failed (the Canceled is discarded)
*
*
*
*
* @param delay the amount of time to sleep before retrying
* @param blk the block to execute and potentially retry
*/
def withRetry(delay: Span)(blk: => Outcome): Outcome = {
val firstOutcome = blk
firstOutcome match {
case Failed(ex) =>
blk match {
case Succeeded => Canceled(Resources("testFlickered"), ex)
case other => firstOutcome
}
case Canceled(ex) =>
blk match {
case Succeeded => Succeeded
case failed: Failed => failed // Never hide a failure.
case other => firstOutcome
}
case other => other
}
}
/**
* Retries the given block immediately (with no delay) if the Outcome of executing
* the block is Failed.
*
*
* The behavior of this method is defined in the table below. The first row shows the main "retry" behavior: if
* executing the block initially fails, and on retry it succeeds, the result is Canceled. The purpose of this is
* to deal with "flickering" tests by downgrading a failure that succeeds on retry
* to a cancelation.
*
*
*
* In the table below, if the “Retry Outcome” has just a dash, the block is not retried.
* Otherwise, the block is retried on the same thread, with no delay.
*
*
*
* First Outcome Retry Outcome Result
*
* Failed
*
*
* Succeeded
*
*
* Canceled (the Succeeded and Failed are
* discarded; the exception from the Failed is the cause of the exception in the Canceled)
*
*
*
*
* Succeeded
*
*
* —
*
*
* Succeeded (no retry)
*
*
*
*
* Pending
*
*
* —
*
*
* Pending (no retry)
*
*
*
*
* Canceled
*
*
* —
*
*
* the Canceled (no retry)
*
*
*
*
* Failed
*
*
* Failed
*
*
* the first Failed (the second Failed is discarded)
*
*
*
*
* Failed
*
*
* Pending
*
*
* the Failed (the Pending is discarded)
*
*
*
*
* Failed
*
*
* Canceled
*
*
* the Failed (the Canceled is discarded)
*
*
*
*
* @param blk the block to execute and potentially retry
*/
def withRetryOnFailure(blk: => Outcome): Outcome = withRetryOnFailure(Span.Zero)(blk)
/**
* Retries the given block immediately with the given delay if the Outcome of executing
* the block is Failed.
*
*
* The behavior of this method is defined in the table below. The first row shows the main "retry" behavior: if
* executing the block initially fails, and on retry it succeeds, the result is Canceled. The purpose of this is
* to deal with "flickering" tests by downgrading a failure that succeeds on retry
* to a cancelation.
*
*
*
* In the table below, if the “Retry Outcome” has just a dash, the block is not retried.
* Otherwise, the block is retried on the same thread, after the given delay.
*
*
*
* First Outcome Retry Outcome Result
*
* Failed
*
*
* Succeeded
*
*
* Canceled (the Succeeded and Failed are
* discarded; the exception from the Failed is the cause of the exception in the Canceled)
*
*
*
*
* Succeeded
*
*
* —
*
*
* Succeeded (no retry)
*
*
*
*
* Pending
*
*
* —
*
*
* Pending (no retry)
*
*
*
*
* Canceled
*
*
* —
*
*
* the Canceled (no retry)
*
*
*
*
* Failed
*
*
* Failed
*
*
* the first Failed (the second Failed is discarded)
*
*
*
*
* Failed
*
*
* Pending
*
*
* the Failed (the Pending is discarded)
*
*
*
*
* Failed
*
*
* Canceled
*
*
* the Failed (the Canceled is discarded)
*
*
*
*
* @param delay the amount of time to sleep before retrying
* @param blk the block to execute and potentially retry
*/
def withRetryOnFailure(delay: Span)(blk: => Outcome): Outcome = {
val firstOutcome = blk
firstOutcome match {
case Failed(ex) =>
if (delay != Span.Zero)
Thread.sleep(delay.millisPart)
blk match {
case Succeeded => Canceled(Resources("testFlickered"), ex)
case other => firstOutcome
}
case other => other
}
}
/**
* Retries the given block immediately (with no delay) if the Outcome of executing
* the block is Canceled.
*
*
* The behavior of this method is defined in the table below. The first row shows the main "retry" behavior: if
* executing the block initially results in Canceled, and on retry it succeeds, the result is Succeeded.
* The purpose of this is to deal with tests that intermittently cancel by ignoring a cancelation that
* succeeds on retry.
*
*
*
* In the table below, if the “Retry Outcome” has just a dash, the block is not retried.
* Otherwise, the block is retried on the same thread, with no delay.
*
*
*
* First Outcome Retry Outcome Result
*
* Canceled
*
*
* Succeeded
*
*
* the Succeeded (the Canceled is discarded)
*
*
*
*
* Succeeded
*
*
* —
*
*
* Succeeded (no retry)
*
*
*
*
* Pending
*
*
* —
*
*
* Pending (no retry)
*
*
*
*
* Failed
*
*
* —
*
*
* Failed (no retry)
*
*
*
*
* Canceled
*
*
* Canceled
*
*
* the first Canceled (the second Canceled is discarded)
*
*
*
*
* Canceled
*
*
* Pending
*
*
* the Canceled (the Pending is discarded)
*
*
*
*
* Canceled
*
*
* Failed
*
*
* the Failed (the Canceled is discarded)
*
*
*
*
* @param blk the block to execute and potentially retry
*/
def withRetryOnCancel(blk: => Outcome): Outcome = withRetryOnCancel(Span.Zero)(blk)
/**
* Retries the given block after the given delay if the Outcome of executing
* the block is Canceled.
*
*
* The behavior of this method is defined in the table below. The first row shows the main "retry" behavior: if
* executing the block initially results in Canceled, and on retry it succeeds, the result is Succeeded.
* The purpose of this is to deal with tests that intermittently cancel by ignoring a cancelation that
* succeeds on retry.
*
*
*
* In the table below, if the “Retry Outcome” has just a dash, the block is not retried.
* Otherwise, the block is retried on the same thread, after the given delay.
*
*
*
* First Outcome Retry Outcome Result
*
* Canceled
*
*
* Succeeded
*
*
* the Succeeded (the Canceled is discarded)
*
*
*
*
* Succeeded
*
*
* —
*
*
* Succeeded (no retry)
*
*
*
*
* Pending
*
*
* —
*
*
* Pending (no retry)
*
*
*
*
* Failed
*
*
* —
*
*
* Failed (no retry)
*
*
*
*
* Canceled
*
*
* Canceled
*
*
* the first Canceled (the second Canceled is discarded)
*
*
*
*
* Canceled
*
*
* Pending
*
*
* the Canceled (the Pending is discarded)
*
*
*
*
* Canceled
*
*
* Failed
*
*
* the Failed (the Canceled is discarded)
*
*
*
*
* @param delay the amount of time to sleep before retrying
* @param blk the block to execute and potentially retry
*/
def withRetryOnCancel(delay: Span)(blk: => Outcome): Outcome = {
val firstOutcome = blk
firstOutcome match {
case Canceled(ex) =>
if (delay != Span.Zero)
Thread.sleep(delay.millisPart)
Thread.sleep(delay.millisPart)
blk match {
case Succeeded => Succeeded
case failed: Failed => failed // Never hide a failure.
case other => firstOutcome
}
case other => other
}
}
/**
* Indicates whether the test described by the given TestData includes the
* tag org.scalatest.tags.Retryable.
*
*
* This method provides an easy way to selectively retry just tests that are flickering. You can
* annotated such problematic tests with Retryable, and just retry those. Here's
* what it might look like:
*
*
*
* override def withFixture(test: NoArgTest) = {
* if (isRetryable(test))
* withRetry { super.withFixture(test) }
* else
* super.withFixture(test)
* }
*
*
*/
def isRetryable(testData: TestData): Boolean = testData.tags.exists(_ == "org.scalatest.tags.Retryable")
}
/**
* Companion object to trait Retries that enables its members to be imported as an
* alternative to mixing them in.
*/
object Retries extends Retries