Add MockMvc Kotlin DSL

This commit introduces a `MockMvc` Kotlin DSL via a set of
extensions like `MockMvc.get` or `MockMvc.request`
that provide a Kotlin idiomatic and easily discoverable
API while staying close to the original Java API design.

Closes gh-1951

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

@@ -0,0 +1,172 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.test.web.servlet
+
+import org.hamcrest.CoreMatchers
+import org.junit.Assert
+import org.junit.Test
+import org.junit.jupiter.api.assertThrows
+import org.springframework.http.HttpMethod
+import org.springframework.http.HttpStatus
+import org.springframework.http.MediaType
+import org.springframework.test.web.Person
+import org.springframework.test.web.servlet.setup.MockMvcBuilders
+import org.springframework.web.bind.annotation.*
+import java.security.Principal
+import java.util.*
+
+/**
+ * [MockMvc] DSL tests that verifies builder, actions and expect blocks.
+ *
+ * @author Clint Checketts
+ * @author Petr Balat
+ * @author Sebastien Deleuze
+ */
+class MockMvcExtensionsTests {
+
+	private val mockMvc = MockMvcBuilders.standaloneSetup(PersonController()).build()
+
+	@Test
+	fun request() {
+		mockMvc.request(HttpMethod.GET, "/person/{name}", "Lee") {
+			secure = true
+			accept = MediaType.APPLICATION_JSON
+			headers {
+				contentLanguage = Locale.FRANCE
+			}
+			principal = Principal { "foo" }
+		} andExpect {
+			status { isOk }
+			content { contentType("application/json;charset=UTF-8") }
+			jsonPath("$.name") { value("Lee") }
+			content { json("""{"someBoolean": false}""", false) }
+		} andDo {
+			print()
+		}
+	}
+
+	@Test
+	fun `request without MockHttpServletRequestDsl`() {
+		mockMvc.request(HttpMethod.GET, "/person/{name}", "Lee") andExpect {
+			status { isOk }
+		} andDo {
+			print()
+		}
+	}
+
+	@Test
+	fun `request with custom matcher and handler`() {
+		var matcherInvoked = false
+		var handlerInvoked = false
+		val matcher = ResultMatcher { matcherInvoked = true }
+		val handler = ResultHandler { handlerInvoked = true }
+		mockMvc.request(HttpMethod.GET, "/person/{name}", "Lee")  andExpect {
+			status { isOk }
+		} andExpect {
+			match(matcher)
+		} andDo {
+			handle(handler)
+		}
+		Assert.assertTrue(matcherInvoked)
+		Assert.assertTrue(handlerInvoked)
+	}
+
+	@Test
+	fun get() {
+		mockMvc.get("/person/{name}", "Lee") {
+				secure = true
+				accept = MediaType.APPLICATION_JSON
+				headers {
+					contentLanguage = Locale.FRANCE
+				}
+				principal = Principal { "foo" }
+		} andExpect {
+			status { isOk }
+			content { contentType("application/json;charset=UTF-8") }
+			jsonPath("$.name") { value("Lee") }
+			content { json("""{"someBoolean": false}""", false) }
+		} andDo {
+			print()
+		}
+	}
+
+	@Test
+	fun post() {
+		mockMvc.post("/person") {
+			content = """{ "name": "foo" }"""
+			headers {
+				accept = listOf(MediaType.APPLICATION_JSON)
+				contentType = MediaType.APPLICATION_JSON
+			}
+		} andExpect {
+			status {
+				isCreated
+			}
+		}
+	}
+
+	@Test
+	fun `negative assertion tests to verify the matchers throw errors when expected`() {
+		val name = "Petr"
+		mockMvc.get("/person/$name") {
+			accept = MediaType.APPLICATION_JSON
+		} andExpect {
+			assertThrows<AssertionError> { content { contentType(MediaType.APPLICATION_ATOM_XML) } }
+			assertThrows<AssertionError> { content { string("Wrong") } }
+			assertThrows<AssertionError> { jsonPath("name", CoreMatchers.`is`("Wrong")) }
+			assertThrows<AssertionError> { content { json("""{"name":"wrong"}""") } }
+			assertThrows<AssertionError> { jsonPath("name") { value("wrong") } }
+			assertThrows<AssertionError> { cookie { value("name", "wrong") } }
+			assertThrows<AssertionError> { flash { attribute<String>("name", "wrong") } }
+			assertThrows<AssertionError> { header { stringValues("name", "wrong") } }
+			assertThrows<AssertionError> { model { attributeExists("name", "wrong") } }
+			assertThrows<AssertionError> { redirectedUrl("wrong/Url") }
+			assertThrows<AssertionError> { redirectedUrlPattern("wrong/Url") }
+			assertThrows<AssertionError> { redirectedUrlPattern("wrong/Url") }
+			assertThrows<AssertionError> { status { isAccepted } }
+			assertThrows<AssertionError> { view { name("wrongName") } }
+			assertThrows<AssertionError> { jsonPath("name") { value("wrong") } }
+		}
+	}
+
+	@Test
+	fun `negative assertion tests for xpath`() {
+		mockMvc.get("/person/Clint") {
+			accept = MediaType.APPLICATION_XML
+		} andExpect {
+			status { isOk }
+			assertThrows<AssertionError> { xpath("//wrong") { nodeCount(1) } }
+		} andDo {
+			print()
+		}
+	}
+
+
+	@RestController
+	private class PersonController {
+
+		@GetMapping("/person/{name}")
+		fun get(@PathVariable name: String): Person {
+			return Person(name)
+		}
+
+		@Suppress("UNUSED_PARAMETER")
+		@PostMapping("/person")
+		@ResponseStatus(HttpStatus.CREATED)
+		fun post(@RequestBody person: Person) {}
+	}
+}