Implement deferToPreviousErrorHandler XML configuration option

[sebastianbergmann]

Since PHPUnit 13.2, PHPUnit takes full ownership of the error handler while your tests run. It installs its own handler, processes every deprecation, notice, warning, and error itself (classifying it, applying the baseline, deduplicating it, and reporting it) and only then forwards the issue to any error handler that was registered before PHPUnit (for example in a bootstrap file).

This was an intentional consequence of #5845, and it is the correct behavior: deciding whether an issue is ignored or reported belongs to PHPUnit, in one place, so that the baseline, --display-deprecations, failOnDeprecation, and the issue-trigger classification all agree.

A side effect is that a custom error handler registered before PHPUnit can no longer suppress issues before PHPUnit sees them. Some setups relied on exactly that, for example Drupal's BootstrapErrorHandler, which filters deprecations against an ignore list and only forwards the rest (see #6705).

This adds a new opt-in boolean attribute on the root <phpunit> element of PHPUnit's XML configuration file:

<phpunit deferToPreviousErrorHandler="true">

When enabled, PHPUnit gives the previously registered error handler the first chance to handle each issue. If that handler reports the issue as handled, PHPUnit does nothing further with it: it is not processed, baselined, or reported. Only issues the previous handler declines are processed by PHPUnit as usual. This restores the pre-13.2 precedence and lets bootstrap-based handlers (such as Drupal's) work as they did before.

The option is off by default; existing behavior is unchanged unless you explicitly turn it on. It can only be set in the XML configuration file (there is no CLI flag).

When the option is enabled, any issue your handler suppresses becomes invisible to PHPUnit: to the baseline, deduplication, trigger classification, --display-deprecations, failOnDeprecation, and to loggers and extensions. PHPUnit can no longer guarantee that its reporting reflects what actually happened during the run.

Because of this, PHPUnit emits a notice on every run while the option is active, stating clearly that issue handling has been delegated outside of PHPUnit's control and that reporting integrity cannot be guaranteed. The notice is always shown. By default, PHPUnit does not exit with a shell exit code indicating failure just because the test runner triggered a notice.

Treat this as a compatibility escape hatch, not a recommended configuration. Prefer PHPUnit's built-in mechanisms for handling deprecations which keep PHPUnit as the single authority over what is reported. Use deferToPreviousErrorHandler="true" only when you specifically need a pre-existing error handler to take precedence.

[github-actions]

API Surface Changes

If any of the additions below are not intended as public API, mark them with @internal in the docblock.

New API Surface

Methods

• PHPUnit\TextUI\Configuration\Configuration::deferToPreviousErrorHandler — public function deferToPreviousErrorHandler(): bool

Modified API Surface

Methods

• PHPUnit\TextUI\Configuration\Configuration::__construct

  - public function __construct(array $cliArguments, ?string $testFilesFile, ?string $configurationFile, ?string $bootstrap, array $bootstrapForTestSuite, bool $cacheResult, ?string $cacheDirectory, ?string $coverageCacheDirectory, Source $source, string $testResultCacheFile, ?string $coverageClover, ?string $coverageCobertura, ?string $coverageCrap4j, int $coverageCrap4jThreshold, ?string $coverageHtml, int $coverageHtmlLowUpperBound, int $coverageHtmlHighLowerBound, string $coverageHtmlColorSuccessLow, string $coverageHtmlColorSuccessLowDark, string $coverageHtmlColorSuccessMedium, string $coverageHtmlColorSuccessMediumDark, string $coverageHtmlColorSuccessHigh, string $coverageHtmlColorSuccessHighDark, string $coverageHtmlColorSuccessBar, string $coverageHtmlColorSuccessBarDark, string $coverageHtmlColorWarning, string $coverageHtmlColorWarningDark, string $coverageHtmlColorWarningBar, string $coverageHtmlColorWarningBarDark, string $coverageHtmlColorDanger, string $coverageHtmlColorDangerDark, string $coverageHtmlColorDangerBar, string $coverageHtmlColorDangerBarDark, string $coverageHtmlColorBreadcrumbs, string $coverageHtmlColorBreadcrumbsDark, ?string $coverageHtmlCustomCssFile, ?string $coverageOpenClover, ?string $coveragePhp, ?string $coverageText, bool $coverageTextShowUncoveredFiles, bool $coverageTextShowOnlySummary, ?string $coverageXml, bool $coverageXmlIncludeSource, bool $pathCoverage, bool $branchCoverage, bool $ignoreDeprecatedCodeUnitsFromCodeCoverage, bool $disableCodeCoverageIgnore, bool $disableCoverageTargeting, bool $failOnAllIssues, bool $failOnDeprecation, bool $failOnPhpunitDeprecation, bool $failOnPhpunitNotice, bool $failOnPhpunitWarning, bool $failOnEmptyTestSuite, bool $failOnIncomplete, bool $failOnNotice, bool $failOnRisky, bool $failOnSkipped, bool $failOnWarning, bool $doNotFailOnDeprecation, bool $doNotFailOnPhpunitDeprecation, bool $doNotFailOnPhpunitNotice, bool $doNotFailOnPhpunitWarning, bool $doNotFailOnEmptyTestSuite, bool $doNotFailOnIncomplete, bool $doNotFailOnNotice, bool $doNotFailOnRisky, bool $doNotFailOnSkipped, bool $doNotFailOnWarning, int $stopOnDefect, int $stopOnDeprecation, ?string $specificDeprecationToStopOn, int $stopOnError, int $stopOnFailure, int $stopOnIncomplete, int $stopOnNotice, int $stopOnRisky, int $stopOnSkipped, int $stopOnWarning, bool $outputToStandardErrorStream, int $columns, bool $noExtensions, ?string $pharExtensionDirectory, array $extensionBootstrappers, bool $backupGlobals, bool $backupStaticProperties, bool $beStrictAboutChangesToGlobalState, bool $colors, bool $processIsolation, bool $enforceTimeLimit, int $defaultTimeLimit, int $diffContext, int $timeoutForSmallTests, int $timeoutForMediumTests, int $timeoutForLargeTests, bool $reportUselessTests, bool $strictCoverage, bool $requireCoverageContribution, bool $disallowTestOutput, bool $displayDetailsOnAllIssues, bool $displayDetailsOnIncompleteTests, bool $displayDetailsOnSkippedTests, bool $displayDetailsOnTestsThatTriggerDeprecations, bool $displayDetailsOnPhpunitDeprecations, bool $displayDetailsOnPhpunitNotices, bool $displayDetailsOnTestsThatTriggerErrors, bool $displayDetailsOnTestsThatTriggerNotices, bool $displayDetailsOnTestsThatTriggerWarnings, bool $reverseDefectList, bool $requireCoverageMetadata, bool $requireSealedMockObjects, bool $noProgress, bool $noResults, bool $noOutput, int $executionOrder, int $executionOrderDefects, bool $resolveDependencies, ?string $logfileTeamcity, ?string $logfileJunit, ?string $logfileOtr, bool $includeGitInformation, bool $includeGitInformationInOtrLogfile, ?string $logfileTestdoxHtml, ?string $logfileTestdoxText, ?string $logEventsText, ?string $logEventsVerboseText, bool $compactOutput, bool $teamCityOutput, bool $testDoxOutput, bool $testDoxOutputSummary, ?array $testsCovering, ?array $testsUsing, ?array $testsRequiringPhpExtension, ?string $filter, ?string $excludeFilter, ?string $testIdFilterFile, ?string $testIdFilter, array $groups, array $excludeGroups, int $randomOrderSeed, bool $includeUncoveredFiles, TestSuiteCollection $testSuite, string $includeTestSuite, string $excludeTestSuite, ?string $defaultTestSuite, bool $ignoreTestSelectionInXmlConfiguration, array $testSuffixes, Php $php, bool $controlGarbageCollector, int $numberOfTestsBeforeGarbageCollection, ?string $generateBaseline, bool $debug, bool $withTelemetry, int $shortenArraysForExportThreshold)
  + public function __construct(array $cliArguments, ?string $testFilesFile, ?string $configurationFile, ?string $bootstrap, array $bootstrapForTestSuite, bool $cacheResult, ?string $cacheDirectory, ?string $coverageCacheDirectory, Source $source, string $testResultCacheFile, ?string $coverageClover, ?string $coverageCobertura, ?string $coverageCrap4j, int $coverageCrap4jThreshold, ?string $coverageHtml, int $coverageHtmlLowUpperBound, int $coverageHtmlHighLowerBound, string $coverageHtmlColorSuccessLow, string $coverageHtmlColorSuccessLowDark, string $coverageHtmlColorSuccessMedium, string $coverageHtmlColorSuccessMediumDark, string $coverageHtmlColorSuccessHigh, string $coverageHtmlColorSuccessHighDark, string $coverageHtmlColorSuccessBar, string $coverageHtmlColorSuccessBarDark, string $coverageHtmlColorWarning, string $coverageHtmlColorWarningDark, string $coverageHtmlColorWarningBar, string $coverageHtmlColorWarningBarDark, string $coverageHtmlColorDanger, string $coverageHtmlColorDangerDark, string $coverageHtmlColorDangerBar, string $coverageHtmlColorDangerBarDark, string $coverageHtmlColorBreadcrumbs, string $coverageHtmlColorBreadcrumbsDark, ?string $coverageHtmlCustomCssFile, ?string $coverageOpenClover, ?string $coveragePhp, ?string $coverageText, bool $coverageTextShowUncoveredFiles, bool $coverageTextShowOnlySummary, ?string $coverageXml, bool $coverageXmlIncludeSource, bool $pathCoverage, bool $branchCoverage, bool $ignoreDeprecatedCodeUnitsFromCodeCoverage, bool $disableCodeCoverageIgnore, bool $disableCoverageTargeting, bool $failOnAllIssues, bool $failOnDeprecation, bool $failOnPhpunitDeprecation, bool $failOnPhpunitNotice, bool $failOnPhpunitWarning, bool $failOnEmptyTestSuite, bool $failOnIncomplete, bool $failOnNotice, bool $failOnRisky, bool $failOnSkipped, bool $failOnWarning, bool $doNotFailOnDeprecation, bool $doNotFailOnPhpunitDeprecation, bool $doNotFailOnPhpunitNotice, bool $doNotFailOnPhpunitWarning, bool $doNotFailOnEmptyTestSuite, bool $doNotFailOnIncomplete, bool $doNotFailOnNotice, bool $doNotFailOnRisky, bool $doNotFailOnSkipped, bool $doNotFailOnWarning, int $stopOnDefect, int $stopOnDeprecation, ?string $specificDeprecationToStopOn, int $stopOnError, int $stopOnFailure, int $stopOnIncomplete, int $stopOnNotice, int $stopOnRisky, int $stopOnSkipped, int $stopOnWarning, bool $outputToStandardErrorStream, int $columns, bool $noExtensions, ?string $pharExtensionDirectory, array $extensionBootstrappers, bool $backupGlobals, bool $backupStaticProperties, bool $beStrictAboutChangesToGlobalState, bool $colors, bool $processIsolation, bool $enforceTimeLimit, int $defaultTimeLimit, int $diffContext, int $timeoutForSmallTests, int $timeoutForMediumTests, int $timeoutForLargeTests, bool $reportUselessTests, bool $strictCoverage, bool $requireCoverageContribution, bool $disallowTestOutput, bool $displayDetailsOnAllIssues, bool $displayDetailsOnIncompleteTests, bool $displayDetailsOnSkippedTests, bool $displayDetailsOnTestsThatTriggerDeprecations, bool $displayDetailsOnPhpunitDeprecations, bool $displayDetailsOnPhpunitNotices, bool $displayDetailsOnTestsThatTriggerErrors, bool $displayDetailsOnTestsThatTriggerNotices, bool $displayDetailsOnTestsThatTriggerWarnings, bool $reverseDefectList, bool $requireCoverageMetadata, bool $requireSealedMockObjects, bool $deferToPreviousErrorHandler, bool $noProgress, bool $noResults, bool $noOutput, int $executionOrder, int $executionOrderDefects, bool $resolveDependencies, ?string $logfileTeamcity, ?string $logfileJunit, ?string $logfileOtr, bool $includeGitInformation, bool $includeGitInformationInOtrLogfile, ?string $logfileTestdoxHtml, ?string $logfileTestdoxText, ?string $logEventsText, ?string $logEventsVerboseText, bool $compactOutput, bool $teamCityOutput, bool $testDoxOutput, bool $testDoxOutputSummary, ?array $testsCovering, ?array $testsUsing, ?array $testsRequiringPhpExtension, ?string $filter, ?string $excludeFilter, ?string $testIdFilterFile, ?string $testIdFilter, array $groups, array $excludeGroups, int $randomOrderSeed, bool $includeUncoveredFiles, TestSuiteCollection $testSuite, string $includeTestSuite, string $excludeTestSuite, ?string $defaultTestSuite, bool $ignoreTestSelectionInXmlConfiguration, array $testSuffixes, Php $php, bool $controlGarbageCollector, int $numberOfTestsBeforeGarbageCollection, ?string $generateBaseline, bool $debug, bool $withTelemetry, int $shortenArraysForExportThreshold)

[codecov]

Codecov Report

❌ Patch coverage is 96.66667% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.56%. Comparing base (d105040) to head (de32a59).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/Runner/ErrorHandler.php	96.80%	3 Missing ⚠️
.../Framework/TestRunner/ErrorHandlerBootstrapper.php	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               13.2    #6708      +/-   ##
============================================
- Coverage     97.56%   97.56%   -0.01%     
- Complexity     8694     8715      +21     
============================================
  Files           868      868              
  Lines         26540    26592      +52     
============================================
+ Hits          25894    25944      +50     
- Misses          646      648       +2     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

[sebastianbergmann]

Superseded by #6710.