Ensure one time logging for request details

Closes gh-26969

spring-test/src/main/java/org/springframework/test/web/reactive/server/ExchangeResult.java

@@ -79,6 +79,9 @@ public class ExchangeResult {
 	@Nullable
 	private final Object mockServerResult;
 
+	/** Ensure single logging, e.g. for expectAll. */
+	private boolean diagnosticsLogged;
+
 
 	/**
 	 * Create an instance with an HTTP request and response along with promises
@@ -121,6 +124,7 @@ public class ExchangeResult {
 		this.timeout = other.timeout;
 		this.uriTemplate = other.uriTemplate;
 		this.mockServerResult = other.mockServerResult;
+		this.diagnosticsLogged = other.diagnosticsLogged;
 	}
 
 
@@ -227,7 +231,8 @@ public class ExchangeResult {
 			assertion.run();
 		}
 		catch (AssertionError ex) {
-			if (logger.isErrorEnabled()) {
+			if (!this.diagnosticsLogged && logger.isErrorEnabled()) {
+				this.diagnosticsLogged = true;
 				logger.error("Request details for assertion failure:\n" + this);
 			}
 			throw ex;

spring-test/src/test/java/org/springframework/test/web/reactive/server/samples/SoftAssertionTests.java

@@ -46,15 +46,19 @@ class SoftAssertionTests {
 	}
 
 	@Test
-	void expectAllWithMultipleFailures() throws Exception {
-		assertThatExceptionOfType(AssertionError.class).isThrownBy(() ->
-			this.webTestClient.get().uri("/test").exchange()
-				.expectAll(
-					responseSpec -> responseSpec.expectStatus().isBadRequest(),
-					responseSpec -> responseSpec.expectStatus().isOk(),
-					responseSpec -> responseSpec.expectBody(String.class).isEqualTo("bogus")
+	void expectAllWithMultipleFailures() {
+		assertThatExceptionOfType(AssertionError.class)
+				.isThrownBy(() ->
+						this.webTestClient.get().uri("/test").exchange()
+								.expectAll(
+										responseSpec -> responseSpec.expectStatus().isBadRequest(),
+										responseSpec -> responseSpec.expectStatus().isOk(),
+										responseSpec -> responseSpec.expectBody(String.class).isEqualTo("bogus")
+								)
 				)
-		).withMessage("Multiple Exceptions (2):\nStatus expected:<400 BAD_REQUEST> but was:<200 OK>\nResponse body expected:<bogus> but was:<hello>");
+				.withMessage("Multiple Exceptions (2):\n" +
+						"Status expected:<400 BAD_REQUEST> but was:<200 OK>\n" +
+						"Response body expected:<bogus> but was:<hello>");
 	}