Polish and add MockMvcExtensionsTests.queryParameter

Closes gh-32371

spring-test/src/main/kotlin/org/springframework/test/web/servlet/MockHttpServletRequestDsl.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -116,6 +116,7 @@ open class MockHttpServletRequestDsl internal constructor (private val builder:
 	var params: MultiValueMap<String, String>? = null
 
 	/**
+	 * @since 6.1.5
 	 * @see [MockHttpServletRequestBuilder.queryParam]
 	 */
 	fun queryParam(name: String, vararg values: String) {

spring-test/src/test/kotlin/org/springframework/test/web/servlet/MockMvcExtensionsTests.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -219,6 +219,16 @@ class MockMvcExtensionsTests {
 						"Content type expected:<text/plain> but was:<application/json>")
 	}
 
+	@Test
+	fun queryParameter() {
+		val result = mockMvc.get("/") {
+			queryParam("foo", "bar")
+			queryParam("foo", "baz")
+		}.andReturn()
+		assertThat(result.request.parameterMap["foo"]).containsExactly("bar", "baz")
+		assertThat(result.request.queryString).isEqualTo("foo=bar&foo=baz")
+	}
+
 
 	@RestController
 	private class PersonController {