Add filters to MockMvc with their init params and dispatcher types

Closes gh-37835

Author: wilkinsona

Diff for: spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/web/servlet/SpringBootMockMvcBuilderCustomizer.java

@@ -116,12 +116,8 @@ private void addFilters(ConfigurableMockMvcBuilder<?> builder) {
 	private void addFilter(ConfigurableMockMvcBuilder<?> builder, AbstractFilterRegistrationBean<?> registration) {
 		Filter filter = registration.getFilter();
 		Collection<String> urls = registration.getUrlPatterns();
-		if (urls.isEmpty()) {
-			builder.addFilters(filter);
-		}
-		else {
-			builder.addFilter(filter, StringUtils.toStringArray(urls));
-		}
+		builder.addFilter(filter, registration.getInitParameters(), registration.determineDispatcherTypes(),
+				StringUtils.toStringArray(urls));
 	}
 
 	public void setAddFilters(boolean addFilters) {

Diff for: spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/web/servlet/SpringBootMockMvcBuilderCustomizerTests.java

@@ -18,16 +18,21 @@
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
+import java.util.EnumSet;
 import java.util.List;
+import java.util.Map;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 
+import jakarta.servlet.DispatcherType;
 import jakarta.servlet.Filter;
 import jakarta.servlet.FilterChain;
 import jakarta.servlet.FilterConfig;
 import jakarta.servlet.ServletRequest;
 import jakarta.servlet.ServletResponse;
 import jakarta.servlet.http.HttpServlet;
+import org.assertj.core.api.InstanceOfAssertFactories;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.test.autoconfigure.web.servlet.SpringBootMockMvcBuilderCustomizer.DeferredLinesWriter;
@@ -37,11 +42,12 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.mock.web.MockServletContext;
-import org.springframework.test.util.ReflectionTestUtils;
 import org.springframework.test.web.servlet.setup.DefaultMockMvcBuilder;
 import org.springframework.test.web.servlet.setup.MockMvcBuilders;
 
+import static org.assertj.core.api.Assertions.as;
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.tuple;
 
 /**
  * Tests for {@link SpringBootMockMvcBuilderCustomizer}.
@@ -51,7 +57,6 @@
 class SpringBootMockMvcBuilderCustomizerTests {
 
 	@Test
-	@SuppressWarnings("unchecked")
 	void customizeShouldAddFilters() {
 		AnnotationConfigServletWebApplicationContext context = new AnnotationConfigServletWebApplicationContext();
 		MockServletContext servletContext = new MockServletContext();
@@ -65,8 +70,11 @@ void customizeShouldAddFilters() {
 			.getBean("filterRegistrationBean");
 		Filter testFilter = (Filter) context.getBean("testFilter");
 		Filter otherTestFilter = registrationBean.getFilter();
-		List<Filter> filters = (List<Filter>) ReflectionTestUtils.getField(builder, "filters");
-		assertThat(filters).containsExactlyInAnyOrder(testFilter, otherTestFilter);
+		assertThat(builder).extracting("filters", as(InstanceOfAssertFactories.LIST))
+			.extracting("delegate", "initParams", "dispatcherTypes")
+			.containsExactlyInAnyOrder(tuple(testFilter, Collections.emptyMap(), EnumSet.of(DispatcherType.REQUEST)),
+					tuple(otherTestFilter, Map.of("a", "alpha", "b", "bravo"),
+							EnumSet.of(DispatcherType.REQUEST, DispatcherType.ERROR)));
 	}
 
 	@Test
@@ -130,7 +138,11 @@ static class FilterConfiguration {
 
 		@Bean
 		FilterRegistrationBean<OtherTestFilter> filterRegistrationBean() {
-			return new FilterRegistrationBean<>(new OtherTestFilter());
+			FilterRegistrationBean<OtherTestFilter> filterRegistrationBean = new FilterRegistrationBean<>(
+					new OtherTestFilter());
+			filterRegistrationBean.setInitParameters(Map.of("a", "alpha", "b", "bravo"));
+			filterRegistrationBean.setDispatcherTypes(EnumSet.of(DispatcherType.REQUEST, DispatcherType.ERROR));
+			return filterRegistrationBean;
 		}
 
 		@Bean
@@ -182,4 +194,9 @@ public void destroy() {
 
 	}
 
+	static record RegisteredFilter(Filter filter, Map<String, String> initParameters,
+			EnumSet<DispatcherType> dispatcherTypes) {
+
+	}
+
 }

Diff for: spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/AbstractFilterRegistrationBean.java

@@ -158,6 +158,28 @@ public void addUrlPatterns(String... urlPatterns) {
 		Collections.addAll(this.urlPatterns, urlPatterns);
 	}
 
+	/**
+	 * Determines the {@link DispatcherType dispatcher types} for which the filter should
+	 * be registered. Applies defaults based on the type of filter being registered if
+	 * none have been configured. Modifications to the returned {@link EnumSet} will have
+	 * no effect on the registration.
+	 * @return the dispatcher types, never {@code null}
+	 * @since 3.2.0
+	 */
+	public EnumSet<DispatcherType> determineDispatcherTypes() {
+		if (this.dispatcherTypes == null) {
+			T filter = getFilter();
+			if (ClassUtils.isPresent("org.springframework.web.filter.OncePerRequestFilter",
+					filter.getClass().getClassLoader()) && filter instanceof OncePerRequestFilter) {
+				return EnumSet.allOf(DispatcherType.class);
+			}
+			else {
+				return EnumSet.of(DispatcherType.REQUEST);
+			}
+		}
+		return EnumSet.copyOf(this.dispatcherTypes);
+	}
+
 	/**
 	 * Convenience method to {@link #setDispatcherTypes(EnumSet) set dispatcher types}
 	 * using the specified elements.
@@ -216,17 +238,7 @@ protected Dynamic addRegistration(String description, ServletContext servletCont
 	@Override
 	protected void configure(FilterRegistration.Dynamic registration) {
 		super.configure(registration);
-		EnumSet<DispatcherType> dispatcherTypes = this.dispatcherTypes;
-		if (dispatcherTypes == null) {
-			T filter = getFilter();
-			if (ClassUtils.isPresent("org.springframework.web.filter.OncePerRequestFilter",
-					filter.getClass().getClassLoader()) && filter instanceof OncePerRequestFilter) {
-				dispatcherTypes = EnumSet.allOf(DispatcherType.class);
-			}
-			else {
-				dispatcherTypes = EnumSet.of(DispatcherType.REQUEST);
-			}
-		}
+		EnumSet<DispatcherType> dispatcherTypes = determineDispatcherTypes();
 		Set<String> servletNames = new LinkedHashSet<>();
 		for (ServletRegistrationBean<?> servletRegistrationBean : this.servletRegistrationBeans) {
 			servletNames.add(servletRegistrationBean.getServletName());