Introduce method in MockHttpServletRequestBuilder to set remote address

Co-authored-by: Sam Brannen <sam@sambrannen.com>
Closes spring-projectsgh-30497

spring-test/src/main/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilder.java

@@ -103,6 +103,9 @@ public class MockHttpServletRequestBuilder
 	@Nullable
 	private MockHttpSession session;
 
+	@Nullable
+	private String remoteAddress;
+
 	@Nullable
 	private String characterEncoding;
 
@@ -525,6 +528,17 @@ public MockHttpServletRequestBuilder principal(Principal principal) {
 		return this;
 	}
 
+	/**
+	 * Set the remote address of the request.
+	 * @param remoteAddress the remote address (IP)
+	 * @since 6.1
+	 */
+	public MockHttpServletRequestBuilder remoteAddress(String remoteAddress) {
+		Assert.hasText(remoteAddress, "'remoteAddress' must not be null or blank");
+		this.remoteAddress = remoteAddress;
+		return this;
+	}
+
 	/**
 	 * An extension point for further initialization of {@link MockHttpServletRequest}
 	 * in ways not built directly into the {@code MockHttpServletRequestBuilder}.
@@ -582,6 +596,9 @@ public Object merge(@Nullable Object parent) {
 		if (this.session == null) {
 			this.session = parentBuilder.session;
 		}
+		if (this.remoteAddress == null) {
+			this.remoteAddress = parentBuilder.remoteAddress;
+		}
 
 		if (this.characterEncoding == null) {
 			this.characterEncoding = parentBuilder.characterEncoding;
@@ -686,6 +703,9 @@ public final MockHttpServletRequest buildRequest(ServletContext servletContext)
 		if (this.principal != null) {
 			request.setUserPrincipal(this.principal);
 		}
+		if (this.remoteAddress != null) {
+			request.setRemoteAddr(this.remoteAddress);
+		}
 		if (this.session != null) {
 			request.setSession(this.session);
 		}

spring-test/src/test/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilderTests.java

@@ -559,6 +559,15 @@ void principal() {
 		assertThat(request.getUserPrincipal()).isEqualTo(user);
 	}
 
+	@Test
+	void remoteAddress() {
+		String ip = "10.0.0.1";
+		this.builder.remoteAddress(ip);
+		MockHttpServletRequest request = this.builder.buildRequest(this.servletContext);
+
+		assertThat(request.getRemoteAddr()).isEqualTo(ip);
+	}
+
 	@Test  // SPR-12945
 	void mergeInvokesDefaultRequestPostProcessorFirst() {
 		final String ATTR = "ATTR";