Fix test .standaloneSetup

Previously, Spring Security's test support did not work well with the
standalone setup. This was because the springSecurityFilterChain was not
found by the WebTestUtils.

This commit ensures that the springSecurityFilterChain is added as a
servlet attribute if it is explicitly defined. WebTestUtils can then
find the springSecurityFilterChain in the ServletContext.

Fixes gh-3881

test/src/main/java/org/springframework/security/test/web/servlet/setup/SecurityMockMvcConfigurer.java

@@ -68,6 +68,8 @@ final class SecurityMockMvcConfigurer extends MockMvcConfigurerAdapter {
 		}
 
 		builder.addFilters(this.springSecurityFilterChain);
+		context.getServletContext().setAttribute(BeanIds.SPRING_SECURITY_FILTER_CHAIN,
+				this.springSecurityFilterChain);
 
 		return testSecurityContext();
 	}

test/src/main/java/org/springframework/security/test/web/support/WebTestUtils.java

@@ -18,9 +18,11 @@ package org.springframework.security.test.web.support;
 import java.util.List;
 
 import javax.servlet.Filter;
+import javax.servlet.ServletContext;
 import javax.servlet.http.HttpServletRequest;
 
 import org.springframework.beans.factory.NoSuchBeanDefinitionException;
+import org.springframework.security.config.BeanIds;
 import org.springframework.security.web.context.AbstractSecurityWebApplicationInitializer;
 import org.springframework.security.web.context.HttpSessionSecurityContextRepository;
 import org.springframework.security.web.context.SecurityContextPersistenceFilter;
@@ -115,18 +117,9 @@ public abstract class WebTestUtils {
 	@SuppressWarnings("unchecked")
 	static <T extends Filter> T findFilter(HttpServletRequest request,
 			Class<T> filterClass) {
-		WebApplicationContext webApplicationContext = WebApplicationContextUtils
-				.getWebApplicationContext(request.getServletContext());
-		if (webApplicationContext == null) {
-			return null;
-		}
-		Filter springSecurityFilterChain = null;
-		try {
-			springSecurityFilterChain = webApplicationContext.getBean(
-					AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME,
-					Filter.class);
-		}
-		catch (NoSuchBeanDefinitionException notFound) {
+		ServletContext servletContext = request.getServletContext();
+		Filter springSecurityFilterChain = getSpringSecurityFilterChain(servletContext);
+		if (springSecurityFilterChain == null) {
 			return null;
 		}
 		List<Filter> filters = (List<Filter>) ReflectionTestUtils
@@ -142,6 +135,26 @@ public abstract class WebTestUtils {
 		return null;
 	}
 
+	private static Filter getSpringSecurityFilterChain(ServletContext servletContext) {
+		Filter result = (Filter) servletContext
+				.getAttribute(BeanIds.SPRING_SECURITY_FILTER_CHAIN);
+		if (result != null) {
+			return result;
+		}
+		WebApplicationContext webApplicationContext = WebApplicationContextUtils
+				.getWebApplicationContext(servletContext);
+		if (webApplicationContext != null) {
+			try {
+				return webApplicationContext.getBean(
+						AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME,
+						Filter.class);
+			}
+			catch (NoSuchBeanDefinitionException notFound) {
+			}
+		}
+		return null;
+	}
+
 	private WebTestUtils() {
 	}
 }