Empty path mapping behaves consistently

An empty path mapping in an @RequestMapping now consistently matches to
empty paths regardless of whether there are both type and method level,
annotations, or method-level only.

Closes gh-22543

spring-test/src/test/java/org/springframework/test/web/servlet/htmlunit/ForwardController.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -28,7 +28,7 @@ public class ForwardController {
 
 	@RequestMapping("/forward")
 	public String forward() {
-		return "forward:/";
+		return "forward:/a";
 	}
 
 }

spring-test/src/test/java/org/springframework/test/web/servlet/htmlunit/HelloController.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -28,7 +28,7 @@ import org.springframework.web.bind.annotation.RestController;
 @RestController
 public class HelloController {
 
-	@RequestMapping
+	@RequestMapping("/a")
 	public String header(HttpServletRequest request) {
 		return "hello";
 	}

spring-test/src/test/java/org/springframework/test/web/servlet/htmlunit/MockMvcConnectionBuilderSupportTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -151,7 +151,7 @@ public class MockMvcConnectionBuilderSupportTests {
 		@RestController
 		static class ContextPathController {
 
-			@RequestMapping
+			@RequestMapping("/def")
 			public String contextPath(HttpServletRequest request) {
 				return request.getContextPath();
 			}

spring-test/src/test/java/org/springframework/test/web/servlet/htmlunit/MockMvcWebClientBuilderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -157,7 +157,7 @@ public class MockMvcWebClientBuilderTests {
 		@RestController
 		static class ContextPathController {
 
-			@RequestMapping
+			@RequestMapping("/test")
 			public String contextPath(HttpServletRequest request) {
 				return "mvc";
 			}

spring-test/src/test/java/org/springframework/test/web/servlet/htmlunit/MockMvcWebConnectionTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -18,6 +18,7 @@ package org.springframework.test.web.servlet.htmlunit;
 
 import java.io.IOException;
 
+import com.gargoylesoftware.htmlunit.FailingHttpStatusCodeException;
 import com.gargoylesoftware.htmlunit.Page;
 import com.gargoylesoftware.htmlunit.WebClient;
 import org.junit.Test;
@@ -44,7 +45,7 @@ public class MockMvcWebConnectionTests {
 
 	@Test
 	public void contextPathNull() throws IOException {
-		this.webClient.setWebConnection(new MockMvcWebConnection(this.mockMvc, this.webClient));
+		this.webClient.setWebConnection(new MockMvcWebConnection(this.mockMvc, this.webClient, null));
 		Page page = this.webClient.getPage("http://localhost/context/a");
 		assertThat(page.getWebResponse().getStatusCode(), equalTo(200));
 	}
@@ -59,8 +60,21 @@ public class MockMvcWebConnectionTests {
 	@Test
 	public void contextPathEmpty() throws IOException {
 		this.webClient.setWebConnection(new MockMvcWebConnection(this.mockMvc, this.webClient, ""));
-		Page page = this.webClient.getPage("http://localhost/context/a");
-		assertThat(page.getWebResponse().getStatusCode(), equalTo(200));
+		try {
+			this.webClient.getPage("http://localhost/context/a");
+			fail("Empty context path (root context) should not match to a URL with a context path");
+		}
+		catch (FailingHttpStatusCodeException ex) {
+			assertEquals(404, ex.getStatusCode());
+		}
+		this.webClient.setWebConnection(new MockMvcWebConnection(this.mockMvc, this.webClient));
+		try {
+			this.webClient.getPage("http://localhost/context/a");
+			fail("No context is the same providing an empty context path");
+		}
+		catch (FailingHttpStatusCodeException ex) {
+			assertEquals(404, ex.getStatusCode());
+		}
 	}
 
 	@Test

spring-test/src/test/java/org/springframework/test/web/servlet/htmlunit/webdriver/MockMvcHtmlUnitDriverBuilderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -145,7 +145,7 @@ public class MockMvcHtmlUnitDriverBuilderTests {
 		@RestController
 		static class ContextPathController {
 
-			@RequestMapping
+			@RequestMapping("/test")
 			public String contextPath(HttpServletRequest request) {
 				return EXPECTED_BODY;
 			}

spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/RedirectTests.java

@@ -115,7 +115,7 @@ public class RedirectTests {
 			return "persons/index";
 		}
 
-		@PostMapping
+		@PostMapping("/persons")
 		public String save(@Valid Person person, Errors errors, RedirectAttributes redirectAttrs) {
 			if (errors.hasErrors()) {
 				return "persons/add";