Propagate TestSecurityContextHolder to SecurityContextHolder

Create SecurityMockMvcResultHandlers to define security related MockMvc ResultHandlers
Create a method to allow copying the SecurityContext from the TestSecurityContextHolder to SecurityContextHolder

Closes gh-9565

test/src/main/java/org/springframework/security/test/web/servlet/response/SecurityMockMvcResultHandlers.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2002-2021 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.security.test.web.servlet.response;
+
+import org.springframework.security.core.context.SecurityContext;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.security.test.context.TestSecurityContextHolder;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.MvcResult;
+import org.springframework.test.web.servlet.ResultHandler;
+
+/**
+ * Security related {@link MockMvc} {@link ResultHandler}s
+ *
+ * @author Marcus da Coregio
+ * @since 5.6
+ */
+public final class SecurityMockMvcResultHandlers {
+
+	private SecurityMockMvcResultHandlers() {
+	}
+
+	/**
+	 * Exports the {@link SecurityContext} from {@link TestSecurityContextHolder} to
+	 * {@link SecurityContextHolder}
+	 */
+	public static ResultHandler exportTestSecurityContext() {
+		return new ExportTestSecurityContextHandler();
+	}
+
+	/**
+	 * A {@link ResultHandler} that copies the {@link SecurityContext} from
+	 * {@link TestSecurityContextHolder} to {@link SecurityContextHolder}
+	 *
+	 * @author Marcus da Coregio
+	 * @since 5.6
+	 */
+	private static class ExportTestSecurityContextHandler implements ResultHandler {
+
+		@Override
+		public void handle(MvcResult result) {
+			SecurityContextHolder.setContext(TestSecurityContextHolder.getContext());
+		}
+
+	}
+
+}