FailureAnalyzer class - spring_boot_starter_test library

Explains a startup error that spring_boot_dart does not know, as an APPLICATION FAILED TO START report instead of a stack trace.

A library that fails the start in a predictable way (a port already in use, a database that cannot be reached, a missing licence key) can tell the developer what happened and how to fix it. Declare the analyzer as a bean (a starter puts it in its auto-configuration), or pass it to SpringApplication(failureAnalyzers: ...). When the start fails, the analyzers passed to the constructor are asked first, then the beans sorted by @Order, then the built-in analysis; the first non-null answer is reported. Analyzer beans are only found when the context got far enough to create them.

analyze receives the error as it was thrown. An error raised while a bean is created is often wrapped in a BeanCreationException, so walk the cause chain when needed.

// The web server could not bind its port.
class PortInUseFailureAnalyzer implements FailureAnalyzer {
  @override
  FailureAnalysis? analyze(Object failure) => failure is PortInUseException
      ? FailureAnalysis(
          'Port ${failure.port} is already in use.',
          'Stop the other process or set server.port.',
          failure,
        )
      : null;
}

Spring (Java):

class PortInUseFailureAnalyzer
    extends AbstractFailureAnalyzer<PortInUseException> {
  @Override
  protected FailureAnalysis analyze(Throwable root, PortInUseException ex) {
    return new FailureAnalysis("Port " + ex.getPort() + " is in use.",
        "Stop the other process or set server.port.", ex);
  }
}

FailureAnalyzer class abstract interface

Properties

Methods

Operators

spring_boot_starter_test library