Support link extraction with official HAL and HAL-FORMS media types

Register the HalLinkExtractor for both the official HAL media type
(application/vnd.hal+json) and the HAL-FORMS media type
(application/prs.hal-forms+json)

See gh-965

Author: odrotbohm

spring-restdocs-core/src/main/java/org/springframework/restdocs/hypermedia/ContentTypeLinkExtractor.java

@@ -30,14 +30,19 @@
  * content type.
  *
  * @author Andy Wilkinson
+ * @author Oliver Drotbohm
  */
 class ContentTypeLinkExtractor implements LinkExtractor {
 
 	private Map<MediaType, LinkExtractor> linkExtractors = new HashMap<>();
 
 	ContentTypeLinkExtractor() {
 		this.linkExtractors.put(MediaType.APPLICATION_JSON, new AtomLinkExtractor());
-		this.linkExtractors.put(HalLinkExtractor.HAL_MEDIA_TYPE, new HalLinkExtractor());
+
+		LinkExtractor halLinkExtractor = new HalLinkExtractor();
+		this.linkExtractors.put(HalLinkExtractor.HAL_MEDIA_TYPE, halLinkExtractor);
+		this.linkExtractors.put(HalLinkExtractor.VND_HAL_MEDIA_TYPE, halLinkExtractor);
+		this.linkExtractors.put(HalLinkExtractor.HAL_FORMS_MEDIA_TYPE, halLinkExtractor);
 	}
 
 	ContentTypeLinkExtractor(Map<MediaType, LinkExtractor> linkExtractors) {

spring-restdocs-core/src/main/java/org/springframework/restdocs/hypermedia/HalLinkExtractor.java

@@ -34,6 +34,8 @@
 class HalLinkExtractor extends AbstractJsonLinkExtractor {
 
 	static final MediaType HAL_MEDIA_TYPE = new MediaType("application", "hal+json");
+	static final MediaType VND_HAL_MEDIA_TYPE = new MediaType("application", "vnd.hal+json");
+	static final MediaType HAL_FORMS_MEDIA_TYPE = new MediaType("application", "prs.hal-forms+json");
 
 	@Override
 	public Map<String, List<Link>> extractLinks(Map<String, Object> json) {

spring-restdocs-core/src/test/java/org/springframework/restdocs/hypermedia/ContentTypeLinkExtractorTests.java

@@ -18,6 +18,7 @@
 
 import java.io.IOException;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import org.junit.jupiter.api.Test;
@@ -28,6 +29,7 @@
 import org.springframework.restdocs.operation.OperationResponse;
 import org.springframework.restdocs.operation.OperationResponseFactory;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
@@ -41,6 +43,8 @@ class ContentTypeLinkExtractorTests {
 
 	private final OperationResponseFactory responseFactory = new OperationResponseFactory();
 
+	private final String halBody = "{ \"_links\" : { \"someRel\" : { \"href\" : \"someHref\" }} }";
+
 	@Test
 	void extractionFailsWithNullContentType() {
 		assertThatIllegalStateException().isThrownBy(() -> new ContentTypeLinkExtractor()
@@ -71,4 +75,22 @@ void extractorCalledWithCompatibleContextType() throws IOException {
 		verify(extractor).extractLinks(response);
 	}
 
+	@Test
+	public void extractsLinksFromVndHalMediaType() throws IOException {
+		HttpHeaders httpHeaders = new HttpHeaders();
+		httpHeaders.setContentType(MediaType.parseMediaType("application/vnd.hal+json"));
+		OperationResponse response = this.responseFactory.create(HttpStatus.OK, httpHeaders, this.halBody.getBytes());
+		Map<String, List<Link>> links = new ContentTypeLinkExtractor().extractLinks(response);
+		assertThat(links).containsKey("someRel");
+	}
+
+	@Test
+	public void extractsLinksFromHalFormsMediaType() throws IOException {
+		HttpHeaders httpHeaders = new HttpHeaders();
+		httpHeaders.setContentType(MediaType.parseMediaType("application/prs.hal-forms+json"));
+		OperationResponse response = this.responseFactory.create(HttpStatus.OK, httpHeaders, this.halBody.getBytes());
+		Map<String, List<Link>> links = new ContentTypeLinkExtractor().extractLinks(response);
+		assertThat(links).containsKey("someRel");
+	}
+
 }