Adds dynamic client registration how-to guide

Closes gh-647

docs/src/test/java/sample/dcr/DynamicClientRegistrationTests.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2020-2023 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
+ *
+ *      https://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 sample.dcr;
+
+import com.jayway.jsonpath.JsonPath;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.web.server.LocalServerPort;
+import org.springframework.context.annotation.Import;
+import org.springframework.http.MediaType;
+import org.springframework.mock.web.MockHttpServletResponse;
+import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.web.reactive.function.client.WebClient;
+
+import static org.springframework.security.test.web.servlet.request.SecurityMockMvcRequestPostProcessors.httpBasic;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+
+/**
+ * Tests for Dynamic Client Registration how-to guide
+ *
+ * @author Dmitriy Dubson
+ */
+@SpringBootTest(
+		webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+		classes = {DynamicClientRegistrationTests.AuthorizationServerConfig.class}
+)
+@AutoConfigureMockMvc
+public class DynamicClientRegistrationTests {
+
+	@Autowired
+	private MockMvc mvc;
+
+	@LocalServerPort
+	private String port;
+
+	@Test
+	public void dynamicallyRegisterAClient() throws Exception {
+		String tokenRequestBody = "scope=client.create&grant_type=client_credentials" ;
+		MockHttpServletResponse tokenResponse = this.mvc.perform(post("/oauth2/token")
+						.with(httpBasic("dcr-client", "secret"))
+						.contentType(MediaType.APPLICATION_FORM_URLENCODED_VALUE)
+						.content(tokenRequestBody))
+				.andExpect(status().isOk())
+				.andExpect(jsonPath("$.access_token").isNotEmpty())
+				.andReturn()
+				.getResponse();
+
+		String initialAccessToken = JsonPath.parse(tokenResponse.getContentAsString()).read("$.access_token");
+
+		WebClient webClient = WebClient.builder().baseUrl("http://127.0.0.1:%s".formatted(port)).build();
+		DcrClient dcrClient = new DcrClient(webClient);
+
+		dcrClient.exampleRegistration(initialAccessToken);
+	}
+
+	@EnableAutoConfiguration
+	@EnableWebSecurity
+	@Import({DcrConfiguration.class, RegisteredClientConfiguration.class})
+	static class AuthorizationServerConfig {
+	}
+}