Make it easier to add new config options to ApplicationContextRunners

Closes gh-27690

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/runner/AbstractApplicationContextRunner.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -105,31 +105,49 @@ import org.springframework.util.Assert;
  */
 public abstract class AbstractApplicationContextRunner<SELF extends AbstractApplicationContextRunner<SELF, C, A>, C extends ConfigurableApplicationContext, A extends ApplicationContextAssertProvider<C>> {
 
-	private final Supplier<C> contextFactory;
-
-	private final boolean allowBeanDefinitionOverriding;
-
-	private final List<ApplicationContextInitializer<? super C>> initializers;
-
-	private final TestPropertyValues environmentProperties;
-
-	private final TestPropertyValues systemProperties;
+	private final RunnerConfiguration<C> runnerConfiguration;
 
-	private final ClassLoader classLoader;
-
-	private final ApplicationContext parent;
-
-	private final List<BeanRegistration<?>> beanRegistrations;
-
-	private final List<Configurations> configurations;
+	private final Function<RunnerConfiguration<C>, SELF> instanceFactory;
 
 	/**
 	 * Create a new {@link AbstractApplicationContextRunner} instance.
 	 * @param contextFactory the factory used to create the actual context
+	 * @deprecated since 2.6.0 for removal in 2.8.0 in favor of
+	 * {@link #AbstractApplicationContextRunner(Supplier, Function)}
 	 */
+	@Deprecated
 	protected AbstractApplicationContextRunner(Supplier<C> contextFactory) {
-		this(contextFactory, false, Collections.emptyList(), TestPropertyValues.empty(), TestPropertyValues.empty(),
-				null, null, Collections.emptyList(), Collections.emptyList());
+		Assert.notNull(contextFactory, "ContextFactory must not be null");
+		this.runnerConfiguration = new RunnerConfiguration<>(contextFactory);
+		this.instanceFactory = this::legacyNewInstance;
+	}
+
+	/**
+	 * Create a new {@link AbstractApplicationContextRunner} instance.
+	 * @param contextFactory the factory used to create the actual context
+	 * @param instanceFactory the factory used to create new instance of the runner
+	 * @since 2.6.0
+	 */
+	protected AbstractApplicationContextRunner(Supplier<C> contextFactory,
+			Function<RunnerConfiguration<C>, SELF> instanceFactory) {
+		Assert.notNull(contextFactory, "ContextFactory must not be null");
+		Assert.notNull(contextFactory, "RunnerConfiguration must not be null");
+		this.runnerConfiguration = new RunnerConfiguration<>(contextFactory);
+		this.instanceFactory = instanceFactory;
+	}
+
+	/**
+	 * Create a new {@link AbstractApplicationContextRunner} instance.
+	 * @param configuration the configuration for the runner to use
+	 * @param instanceFactory the factory used to create new instance of the runner
+	 * @since 2.6.0
+	 */
+	protected AbstractApplicationContextRunner(RunnerConfiguration<C> configuration,
+			Function<RunnerConfiguration<C>, SELF> instanceFactory) {
+		Assert.notNull(configuration, "RunnerConfiguration must not be null");
+		Assert.notNull(instanceFactory, "instanceFactory must not be null");
+		this.runnerConfiguration = configuration;
+		this.instanceFactory = instanceFactory;
 	}
 
 	/**
@@ -143,7 +161,10 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	 * @param parent the parent
 	 * @param beanRegistrations the bean registrations
 	 * @param configurations the configuration
+	 * @deprecated since 2.6.0 for removal in 2.8.0 in favor of
+	 * {@link #AbstractApplicationContextRunner(Supplier, Function)}
 	 */
+	@Deprecated
 	protected AbstractApplicationContextRunner(Supplier<C> contextFactory, boolean allowBeanDefinitionOverriding,
 			List<ApplicationContextInitializer<? super C>> initializers, TestPropertyValues environmentProperties,
 			TestPropertyValues systemProperties, ClassLoader classLoader, ApplicationContext parent,
@@ -153,15 +174,17 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 		Assert.notNull(systemProperties, "SystemProperties must not be null");
 		Assert.notNull(configurations, "Configurations must not be null");
 		Assert.notNull(initializers, "Initializers must not be null");
-		this.contextFactory = contextFactory;
-		this.allowBeanDefinitionOverriding = allowBeanDefinitionOverriding;
-		this.initializers = Collections.unmodifiableList(initializers);
-		this.environmentProperties = environmentProperties;
-		this.systemProperties = systemProperties;
-		this.classLoader = classLoader;
-		this.parent = parent;
-		this.beanRegistrations = Collections.unmodifiableList(beanRegistrations);
-		this.configurations = Collections.unmodifiableList(configurations);
+		RunnerConfiguration<C> configuration = new RunnerConfiguration<>(contextFactory);
+		configuration.allowBeanDefinitionOverriding = allowBeanDefinitionOverriding;
+		configuration.initializers = Collections.unmodifiableList(initializers);
+		configuration.environmentProperties = environmentProperties;
+		configuration.systemProperties = systemProperties;
+		configuration.classLoader = classLoader;
+		configuration.parent = parent;
+		configuration.beanRegistrations = Collections.unmodifiableList(beanRegistrations);
+		configuration.configurations = Collections.unmodifiableList(configurations);
+		this.runnerConfiguration = configuration;
+		this.instanceFactory = this::legacyNewInstance;
 	}
 
 	/**
@@ -173,9 +196,7 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	 * @see DefaultListableBeanFactory#setAllowBeanDefinitionOverriding(boolean)
 	 */
 	public SELF withAllowBeanDefinitionOverriding(boolean allowBeanDefinitionOverriding) {
-		return newInstance(this.contextFactory, allowBeanDefinitionOverriding, this.initializers,
-				this.environmentProperties, this.systemProperties, this.classLoader, this.parent,
-				this.beanRegistrations, this.configurations);
+		return newInstance(this.runnerConfiguration.withAllowBeanDefinitionOverriding(allowBeanDefinitionOverriding));
 	}
 
 	/**
@@ -186,9 +207,7 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	 */
 	public SELF withInitializer(ApplicationContextInitializer<? super C> initializer) {
 		Assert.notNull(initializer, "Initializer must not be null");
-		return newInstance(this.contextFactory, this.allowBeanDefinitionOverriding, add(this.initializers, initializer),
-				this.environmentProperties, this.systemProperties, this.classLoader, this.parent,
-				this.beanRegistrations, this.configurations);
+		return newInstance(this.runnerConfiguration.withInitializer(initializer));
 	}
 
 	/**
@@ -202,9 +221,7 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	 * @see #withSystemProperties(String...)
 	 */
 	public SELF withPropertyValues(String... pairs) {
-		return newInstance(this.contextFactory, this.allowBeanDefinitionOverriding, this.initializers,
-				this.environmentProperties.and(pairs), this.systemProperties, this.classLoader, this.parent,
-				this.beanRegistrations, this.configurations);
+		return newInstance(this.runnerConfiguration.withPropertyValues(pairs));
 	}
 
 	/**
@@ -218,9 +235,7 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	 * @see #withSystemProperties(String...)
 	 */
 	public SELF withSystemProperties(String... pairs) {
-		return newInstance(this.contextFactory, this.allowBeanDefinitionOverriding, this.initializers,
-				this.environmentProperties, this.systemProperties.and(pairs), this.classLoader, this.parent,
-				this.beanRegistrations, this.configurations);
+		return newInstance(this.runnerConfiguration.withSystemProperties(pairs));
 	}
 
 	/**
@@ -231,9 +246,7 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	 * @see FilteredClassLoader
 	 */
 	public SELF withClassLoader(ClassLoader classLoader) {
-		return newInstance(this.contextFactory, this.allowBeanDefinitionOverriding, this.initializers,
-				this.environmentProperties, this.systemProperties, classLoader, this.parent, this.beanRegistrations,
-				this.configurations);
+		return newInstance(this.runnerConfiguration.withClassLoader(classLoader));
 	}
 
 	/**
@@ -243,9 +256,7 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	 * @return a new instance with the updated parent
 	 */
 	public SELF withParent(ApplicationContext parent) {
-		return newInstance(this.contextFactory, this.allowBeanDefinitionOverriding, this.initializers,
-				this.environmentProperties, this.systemProperties, this.classLoader, parent, this.beanRegistrations,
-				this.configurations);
+		return newInstance(this.runnerConfiguration.withParent(parent));
 	}
 
 	/**
@@ -280,9 +291,7 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	 * @return a new instance with the updated bean
 	 */
 	public <T> SELF withBean(String name, Class<T> type, Object... constructorArgs) {
-		return newInstance(this.contextFactory, this.allowBeanDefinitionOverriding, this.initializers,
-				this.environmentProperties, this.systemProperties, this.classLoader, this.parent,
-				add(this.beanRegistrations, new BeanRegistration<>(name, type, constructorArgs)), this.configurations);
+		return newInstance(this.runnerConfiguration.withBean(name, type, constructorArgs));
 	}
 
 	/**
@@ -320,10 +329,7 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	 */
 	public <T> SELF withBean(String name, Class<T> type, Supplier<T> supplier,
 			BeanDefinitionCustomizer... customizers) {
-		return newInstance(this.contextFactory, this.allowBeanDefinitionOverriding, this.initializers,
-				this.environmentProperties, this.systemProperties, this.classLoader, this.parent,
-				add(this.beanRegistrations, new BeanRegistration<>(name, type, supplier, customizers)),
-				this.configurations);
+		return newInstance(this.runnerConfiguration.withBean(name, type, supplier, customizers));
 	}
 
 	/**
@@ -343,9 +349,7 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	 */
 	public SELF withConfiguration(Configurations configurations) {
 		Assert.notNull(configurations, "Configurations must not be null");
-		return newInstance(this.contextFactory, this.allowBeanDefinitionOverriding, this.initializers,
-				this.environmentProperties, this.systemProperties, this.classLoader, this.parent,
-				this.beanRegistrations, add(this.configurations, configurations));
+		return newInstance(this.runnerConfiguration.withConfiguration(configurations));
 	}
 
 	/**
@@ -358,17 +362,24 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 		return customizer.apply((SELF) this);
 	}
 
-	private <T> List<T> add(List<T> list, T element) {
-		List<T> result = new ArrayList<>(list);
-		result.add(element);
-		return result;
+	@Deprecated
+	private SELF legacyNewInstance(RunnerConfiguration<C> configuration) {
+		return newInstance(configuration.contextFactory, configuration.allowBeanDefinitionOverriding,
+				configuration.initializers, configuration.environmentProperties, configuration.systemProperties,
+				configuration.classLoader, configuration.parent, configuration.beanRegistrations,
+				configuration.configurations);
 	}
 
+	@Deprecated
 	protected abstract SELF newInstance(Supplier<C> contextFactory, boolean allowBeanDefinitionOverriding,
 			List<ApplicationContextInitializer<? super C>> initializers, TestPropertyValues environmentProperties,
 			TestPropertyValues systemProperties, ClassLoader classLoader, ApplicationContext parent,
 			List<BeanRegistration<?>> beanRegistrations, List<Configurations> configurations);
 
+	private SELF newInstance(RunnerConfiguration<C> runnerConfiguration) {
+		return this.instanceFactory.apply(runnerConfiguration);
+	}
+
 	/**
 	 * Create and refresh a new {@link ApplicationContext} based on the current state of
 	 * this loader. The context is consumed by the specified {@code consumer} and closed
@@ -378,7 +389,8 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	 */
 	@SuppressWarnings("unchecked")
 	public SELF run(ContextConsumer<? super A> consumer) {
-		withContextClassLoader(this.classLoader, () -> this.systemProperties.applyToSystemProperties(() -> {
+		withContextClassLoader(this.runnerConfiguration.classLoader,
+				() -> this.runnerConfiguration.systemProperties.applyToSystemProperties(() -> {
 					try (A context = createAssertableContext()) {
 						accept(consumer, context);
 					}
@@ -413,11 +425,11 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	}
 
 	private C createAndLoadContext() {
-		C context = this.contextFactory.get();
+		C context = this.runnerConfiguration.contextFactory.get();
 		ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
 		if (beanFactory instanceof DefaultListableBeanFactory) {
 			((DefaultListableBeanFactory) beanFactory)
-					.setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);
+					.setAllowBeanDefinitionOverriding(this.runnerConfiguration.allowBeanDefinitionOverriding);
 		}
 		try {
 			configureContext(context);
@@ -430,20 +442,20 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	}
 
 	private void configureContext(C context) {
-		if (this.parent != null) {
-			context.setParent(this.parent);
+		if (this.runnerConfiguration.parent != null) {
+			context.setParent(this.runnerConfiguration.parent);
 		}
-		if (this.classLoader != null) {
+		if (this.runnerConfiguration.classLoader != null) {
 			Assert.isInstanceOf(DefaultResourceLoader.class, context);
-			((DefaultResourceLoader) context).setClassLoader(this.classLoader);
+			((DefaultResourceLoader) context).setClassLoader(this.runnerConfiguration.classLoader);
 		}
-		this.environmentProperties.applyTo(context);
-		Class<?>[] classes = Configurations.getClasses(this.configurations);
+		this.runnerConfiguration.environmentProperties.applyTo(context);
+		Class<?>[] classes = Configurations.getClasses(this.runnerConfiguration.configurations);
 		if (classes.length > 0) {
 			((AnnotationConfigRegistry) context).register(classes);
 		}
-		this.beanRegistrations.forEach((registration) -> registration.apply(context));
-		this.initializers.forEach((initializer) -> initializer.initialize(context));
+		this.runnerConfiguration.beanRegistrations.forEach((registration) -> registration.apply(context));
+		this.runnerConfiguration.initializers.forEach((initializer) -> initializer.initialize(context));
 		context.refresh();
 	}
 
@@ -466,7 +478,7 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 	 *
 	 * @param <T> the bean type
 	 */
-	protected final class BeanRegistration<T> {
+	protected static final class BeanRegistration<T> {
 
 		Consumer<GenericApplicationContext> registrar;
 
@@ -486,4 +498,107 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 
 	}
 
+	protected static final class RunnerConfiguration<C extends ConfigurableApplicationContext> {
+
+		private final Supplier<C> contextFactory;
+
+		private boolean allowBeanDefinitionOverriding = false;
+
+		private List<ApplicationContextInitializer<? super C>> initializers = Collections.emptyList();
+
+		private TestPropertyValues environmentProperties = TestPropertyValues.empty();
+
+		private TestPropertyValues systemProperties = TestPropertyValues.empty();
+
+		private ClassLoader classLoader;
+
+		private ApplicationContext parent;
+
+		private List<BeanRegistration<?>> beanRegistrations = Collections.emptyList();
+
+		private List<Configurations> configurations = Collections.emptyList();
+
+		private RunnerConfiguration(Supplier<C> contextFactory) {
+			this.contextFactory = contextFactory;
+		}
+
+		private RunnerConfiguration(RunnerConfiguration<C> source) {
+			this.contextFactory = source.contextFactory;
+			this.allowBeanDefinitionOverriding = source.allowBeanDefinitionOverriding;
+			this.initializers = source.initializers;
+			this.environmentProperties = source.environmentProperties;
+			this.systemProperties = source.systemProperties;
+			this.classLoader = source.classLoader;
+			this.parent = source.parent;
+			this.beanRegistrations = source.beanRegistrations;
+			this.configurations = source.configurations;
+		}
+
+		private RunnerConfiguration<C> withAllowBeanDefinitionOverriding(boolean allowBeanDefinitionOverriding) {
+			RunnerConfiguration<C> config = new RunnerConfiguration<>(this);
+			config.allowBeanDefinitionOverriding = allowBeanDefinitionOverriding;
+			return config;
+		}
+
+		private RunnerConfiguration<C> withInitializer(ApplicationContextInitializer<? super C> initializer) {
+			Assert.notNull(initializer, "Initializer must not be null");
+			RunnerConfiguration<C> config = new RunnerConfiguration<>(this);
+			config.initializers = add(config.initializers, initializer);
+			return config;
+		}
+
+		private RunnerConfiguration<C> withPropertyValues(String... pairs) {
+			RunnerConfiguration<C> config = new RunnerConfiguration<>(this);
+			config.environmentProperties = config.environmentProperties.and(pairs);
+			return config;
+		}
+
+		private RunnerConfiguration<C> withSystemProperties(String... pairs) {
+			RunnerConfiguration<C> config = new RunnerConfiguration<>(this);
+			config.systemProperties = config.systemProperties.and(pairs);
+			return config;
+		}
+
+		private RunnerConfiguration<C> withClassLoader(ClassLoader classLoader) {
+			RunnerConfiguration<C> config = new RunnerConfiguration<>(this);
+			config.classLoader = classLoader;
+			return config;
+		}
+
+		private RunnerConfiguration<C> withParent(ApplicationContext parent) {
+			RunnerConfiguration<C> config = new RunnerConfiguration<>(this);
+			config.parent = parent;
+			return config;
+		}
+
+		private <T> RunnerConfiguration<C> withBean(String name, Class<T> type, Object... constructorArgs) {
+			RunnerConfiguration<C> config = new RunnerConfiguration<>(this);
+			config.beanRegistrations = add(config.beanRegistrations,
+					new BeanRegistration<>(name, type, constructorArgs));
+			return config;
+		}
+
+		private <T> RunnerConfiguration<C> withBean(String name, Class<T> type, Supplier<T> supplier,
+				BeanDefinitionCustomizer... customizers) {
+			RunnerConfiguration<C> config = new RunnerConfiguration<>(this);
+			config.beanRegistrations = add(config.beanRegistrations,
+					new BeanRegistration<>(name, type, supplier, customizers));
+			return config;
+		}
+
+		private RunnerConfiguration<C> withConfiguration(Configurations configurations) {
+			Assert.notNull(configurations, "Configurations must not be null");
+			RunnerConfiguration<C> config = new RunnerConfiguration<>(this);
+			config.configurations = add(config.configurations, configurations);
+			return config;
+		}
+
+		private static <T> List<T> add(List<T> list, T element) {
+			List<T> result = new ArrayList<>(list);
+			result.add(element);
+			return result;
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/runner/ApplicationContextRunner.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -55,9 +55,14 @@ public class ApplicationContextRunner extends
 	 * @param contextFactory a supplier that returns a new instance on each call
 	 */
 	public ApplicationContextRunner(Supplier<ConfigurableApplicationContext> contextFactory) {
-		super(contextFactory);
+		super(contextFactory, ApplicationContextRunner::new);
 	}
 
+	private ApplicationContextRunner(RunnerConfiguration<ConfigurableApplicationContext> runnerConfiguration) {
+		super(runnerConfiguration, ApplicationContextRunner::new);
+	}
+
+	@Deprecated
 	private ApplicationContextRunner(Supplier<ConfigurableApplicationContext> contextFactory,
 			boolean allowBeanDefinitionOverriding,
 			List<ApplicationContextInitializer<? super ConfigurableApplicationContext>> initializers,
@@ -69,6 +74,7 @@ public class ApplicationContextRunner extends
 	}
 
 	@Override
+	@Deprecated
 	protected ApplicationContextRunner newInstance(Supplier<ConfigurableApplicationContext> contextFactory,
 			boolean allowBeanDefinitionOverriding,
 			List<ApplicationContextInitializer<? super ConfigurableApplicationContext>> initializers,

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/runner/ReactiveWebApplicationContextRunner.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -55,9 +55,15 @@ public final class ReactiveWebApplicationContextRunner extends
 	 * @param contextFactory a supplier that returns a new instance on each call
 	 */
 	public ReactiveWebApplicationContextRunner(Supplier<ConfigurableReactiveWebApplicationContext> contextFactory) {
-		super(contextFactory);
+		super(contextFactory, ReactiveWebApplicationContextRunner::new);
 	}
 
+	private ReactiveWebApplicationContextRunner(
+			RunnerConfiguration<ConfigurableReactiveWebApplicationContext> configuration) {
+		super(configuration, ReactiveWebApplicationContextRunner::new);
+	}
+
+	@Deprecated
 	private ReactiveWebApplicationContextRunner(Supplier<ConfigurableReactiveWebApplicationContext> contextFactory,
 			boolean allowBeanDefinitionOverriding,
 			List<ApplicationContextInitializer<? super ConfigurableReactiveWebApplicationContext>> initializers,
@@ -69,6 +75,7 @@ public final class ReactiveWebApplicationContextRunner extends
 	}
 
 	@Override
+	@Deprecated
 	protected ReactiveWebApplicationContextRunner newInstance(
 			Supplier<ConfigurableReactiveWebApplicationContext> contextFactory, boolean allowBeanDefinitionOverriding,
 			List<ApplicationContextInitializer<? super ConfigurableReactiveWebApplicationContext>> initializers,

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/runner/WebApplicationContextRunner.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -59,9 +59,14 @@ public final class WebApplicationContextRunner extends
 	 * @param contextFactory a supplier that returns a new instance on each call
 	 */
 	public WebApplicationContextRunner(Supplier<ConfigurableWebApplicationContext> contextFactory) {
-		super(contextFactory);
+		super(contextFactory, WebApplicationContextRunner::new);
 	}
 
+	private WebApplicationContextRunner(RunnerConfiguration<ConfigurableWebApplicationContext> configuration) {
+		super(configuration, WebApplicationContextRunner::new);
+	}
+
+	@Deprecated
 	private WebApplicationContextRunner(Supplier<ConfigurableWebApplicationContext> contextFactory,
 			boolean allowBeanDefinitionOverriding,
 			List<ApplicationContextInitializer<? super ConfigurableWebApplicationContext>> initializers,
@@ -73,6 +78,7 @@ public final class WebApplicationContextRunner extends
 	}
 
 	@Override
+	@Deprecated
 	protected WebApplicationContextRunner newInstance(Supplier<ConfigurableWebApplicationContext> contextFactory,
 			boolean allowBeanDefinitionOverriding,
 			List<ApplicationContextInitializer<? super ConfigurableWebApplicationContext>> initializers,