Add Kotlin DSL support for MockMVC andExpectAll (#29727)

As the DSL internally calls `ResultActions.andExpect`, this is done with
a trick where a synthetic `ResultActions` is provided at top level which
stores each `ResultMatcher` in a mutable list.

Once the DSL usage is done, the top level DSL `andExpectAll` turns that
list into a `vararg` passed down to the actual `actions.andExpectAll`.

Closes gh-27317

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

@@ -145,4 +145,12 @@ class MockMvcResultMatchersDsl internal constructor (private val actions: Result
 	fun match(matcher: ResultMatcher) {
 		actions.andExpect(matcher)
 	}
+
+	/**
+	 * @since 6.0.4
+	 * @see ResultActions.andExpectAll
+	 */
+	fun matchAll(vararg matchers: ResultMatcher) {
+		actions.andExpectAll(*matchers)
+	}
 }

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

@@ -19,6 +19,35 @@ class ResultActionsDsl internal constructor (private val actions: ResultActions,
 		return this
 	}
 
+
+	/**
+	 * Provide access to [MockMvcResultMatchersDsl] Kotlin DSL.
+	 * @since 6.0.4
+	 * @see MockMvcResultMatchersDsl.matchAll
+	 */
+	fun andExpectAll(dsl: MockMvcResultMatchersDsl.() -> Unit): ResultActionsDsl {
+		val softMatchers = mutableListOf<ResultMatcher>()
+		val softActions = object : ResultActions {
+			override fun andExpect(matcher: ResultMatcher): ResultActions {
+				softMatchers.add(matcher)
+				return this
+			}
+
+			override fun andDo(handler: ResultHandler): ResultActions {
+				throw UnsupportedOperationException("andDo should not be part of andExpectAll DSL calls")
+			}
+
+			override fun andReturn(): MvcResult {
+				throw UnsupportedOperationException("andReturn should not be part of andExpectAll DSL calls")
+			}
+
+		}
+		// the use of softActions as the matchers DSL actions parameter will store ResultMatchers in list
+		MockMvcResultMatchersDsl(softActions).dsl()
+		actions.andExpectAll(*softMatchers.toTypedArray())
+		return this;
+	}
+
 	/**
 	 * Provide access to [MockMvcResultHandlersDsl] Kotlin DSL.
 	 * @see MockMvcResultHandlersDsl.handle