Introduced adding of custom WireMock extensions (#429)

without this change we set only a single extension "response-transformer" without an option to provide any other ones
with this change we introduce the "spring.factories" based extension model. It's enough to provide your own implementation of `org.springframework.cloud.contract.verifier.dsl.wiremock.WireMockExtensions` and register it in `spring.factories`. That way you can control all extensions (request / response).

fixes #425

spring-cloud-contract-stub-runner/src/main/java/org/springframework/cloud/contract/stubrunner/provider/wiremock/WireMockHttpServerStub.java

@@ -8,27 +8,28 @@ import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import com.github.tomakehurst.wiremock.WireMockServer;
 import com.github.tomakehurst.wiremock.client.WireMock;
 import com.github.tomakehurst.wiremock.common.Slf4jNotifier;
 import com.github.tomakehurst.wiremock.core.WireMockConfiguration;
-import com.github.tomakehurst.wiremock.extension.responsetemplating.ResponseTemplateTransformer;
+import com.github.tomakehurst.wiremock.extension.Extension;
 import com.github.tomakehurst.wiremock.stubbing.StubMapping;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-
 import org.springframework.cloud.contract.stubrunner.HttpServerStub;
 import org.springframework.cloud.contract.verifier.builder.handlebars.HandlebarsEscapeHelper;
 import org.springframework.cloud.contract.verifier.builder.handlebars.HandlebarsJsonPathHelper;
+import org.springframework.cloud.contract.verifier.dsl.wiremock.DefaultResponseTransformer;
+import org.springframework.cloud.contract.verifier.dsl.wiremock.WireMockExtensions;
 import org.springframework.cloud.contract.wiremock.WireMockSpring;
+import org.springframework.core.io.support.SpringFactoriesLoader;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.SocketUtils;
 import org.springframework.util.StreamUtils;
 import org.springframework.util.StringUtils;
-
 import wiremock.com.github.jknack.handlebars.Helper;
 
 /**
@@ -47,18 +48,32 @@ public class WireMockHttpServerStub implements HttpServerStub {
 	private WireMockConfiguration config() {
 		if (ClassUtils.isPresent("org.springframework.cloud.contract.wiremock.WireMockSpring", null)) {
 			return WireMockSpring.options()
-					.extensions(responseTemplateTransformer());
+					.extensions(responseTransformers());
 		}
-		return new WireMockConfiguration().extensions(responseTemplateTransformer());
+		return new WireMockConfiguration().extensions(responseTransformers());
 	}
 
-	private ResponseTemplateTransformer responseTemplateTransformer() {
-		return new ResponseTemplateTransformer(false, helpers());
+	private Extension[] responseTransformers() {
+		List<WireMockExtensions> wireMockExtensions = SpringFactoriesLoader
+				.loadFactories(WireMockExtensions.class, null);
+		List<Extension> extensions = new ArrayList<>();
+		if (!wireMockExtensions.isEmpty()) {
+			for (WireMockExtensions wireMockExtension : wireMockExtensions) {
+				extensions.addAll(wireMockExtension.extensions());
+			}
+		} else {
+			extensions.add(new DefaultResponseTransformer(false, helpers()));
+		}
+		return extensions.toArray(new Extension[extensions.size()]);
 	}
 
 	/**
 	 * Override this if you want to register your own helpers
+	 *
+	 * @deprecated - please use the {@link WireMockExtensions} mechanism and pass
+	 * the helpers in your implementation
 	 */
+	@Deprecated
 	protected Map<String, Helper> helpers() {
 		Map<String, Helper> helpers = new HashMap<>();
 		helpers.put(HandlebarsJsonPathHelper.NAME, new HandlebarsJsonPathHelper());

spring-cloud-contract-stub-runner/src/test/groovy/org/springframework/cloud/contract/stubrunner/provider/wiremock/TestWireMockExtensions.groovy

@@ -0,0 +1,56 @@
+package org.springframework.cloud.contract.stubrunner.provider.wiremock
+
+import com.github.tomakehurst.wiremock.common.FileSource
+import com.github.tomakehurst.wiremock.extension.Extension
+import com.github.tomakehurst.wiremock.extension.Parameters
+import com.github.tomakehurst.wiremock.extension.ResponseTransformer
+import com.github.tomakehurst.wiremock.http.Request
+import com.github.tomakehurst.wiremock.http.Response
+
+import org.springframework.cloud.contract.verifier.dsl.wiremock.DefaultResponseTransformer
+import org.springframework.cloud.contract.verifier.dsl.wiremock.WireMockExtensions
+
+/**
+ * Extension that registers the default response transformer and a custom one too
+ */
+class TestWireMockExtensions implements WireMockExtensions {
+	@Override
+	List<Extension> extensions() {
+		return [
+				new DefaultResponseTransformer(),
+				new CustomExtension()
+		]
+	}
+}
+
+class CustomExtension extends ResponseTransformer {
+
+	/**
+	 * We expect the mapping to contain "foo-transformer" in the list
+	 * of "response-transformers" in the stub mapping
+	 */
+	@Override
+	String getName() {
+		return "foo-transformer"
+	}
+
+	/**
+	 * Transformer returns the "surprise!" body regardless of what you
+	 * the stub mapping returns
+	 */
+	@Override
+	Response transform(Request request, Response response, FileSource files, Parameters parameters) {
+		return new Response(response.status, response.statusMessage,
+				"surprise!", response.headers, response.wasConfigured(), response.fault, response.fromProxy)
+	}
+
+	/**
+	 * We don't want this extension to be applied to every single mapping.
+	 * We just want this to take place when a mapping explicitly expresses that in the
+	 * "response-transformers" section
+	 */
+	@Override
+	boolean applyGlobally() {
+		return false
+	}
+}

spring-cloud-contract-stub-runner/src/test/groovy/org/springframework/cloud/contract/stubrunner/provider/wiremock/WireMockHttpServerStubSpec.groovy

@@ -23,31 +23,35 @@ import spock.lang.Specification
 
 import org.springframework.boot.test.rule.OutputCapture
 import org.springframework.boot.test.web.client.TestRestTemplate
+import org.springframework.web.client.RestTemplate
 
 class WireMockHttpServerStubSpec extends Specification {
 	public static
-	final File MAPPING_DESCRIPTOR = new File('src/test/resources/repository/mappings/spring/cloud/ping/ping.json')
+	final File MAPPING_DESCRIPTOR = new File('src/test/resources/transformers.json')
 
 	@Rule OutputCapture capture = new OutputCapture()
 
 	def 'should describe stub mapping'() {
 		given:
-		WireMockHttpServerStub mappingDescriptor = new WireMockHttpServerStub().start() as WireMockHttpServerStub
-
+			WireMockHttpServerStub mappingDescriptor = new WireMockHttpServerStub().start() as WireMockHttpServerStub
 		when:
-		StubMapping mapping = mappingDescriptor.getMapping(MAPPING_DESCRIPTOR)
-
+			StubMapping mapping = mappingDescriptor.getMapping(MAPPING_DESCRIPTOR)
 		then:
-		with(mapping) {
-			assert request.method == RequestMethod.GET
-			assert request.url == '/ping'
-			assert response.status == 200
-			assert response.body == 'pong'
-			assert response.headers.contentTypeHeader.mimeTypePart() == 'text/plain'
-		}
-
+			with(mapping) {
+				assert request.method == RequestMethod.GET
+				assert request.url == '/ping'
+				assert response.status == 200
+				assert response.body == 'pong'
+				assert response.headers.contentTypeHeader.mimeTypePart() == 'text/plain'
+			}
+		when:
+			mappingDescriptor.registerMappings([MAPPING_DESCRIPTOR])
+		then:
+			noExceptionThrown()
+		expect:
+			"surprise!" == new RestTemplate().getForObject("http://localhost:" + mappingDescriptor.port() + "/ping", String.class)
 		cleanup:
-		mappingDescriptor.stop()
+			mappingDescriptor.stop()
 	}
 
 	def 'should make WireMock print out logs on INFO'() {

spring-cloud-contract-stub-runner/src/test/resources/META-INF/spring.factories

@@ -0,0 +1,2 @@
+org.springframework.cloud.contract.verifier.dsl.wiremock.WireMockExtensions=\
+org.springframework.cloud.contract.stubrunner.provider.wiremock.TestWireMockExtensions

spring-cloud-contract-stub-runner/src/test/resources/transformers.json

@@ -0,0 +1,14 @@
+{
+    "request": {
+        "method": "GET",
+        "url": "/ping"
+    },
+    "response": {
+        "status": 200,
+        "body": "pong",
+        "headers": {
+            "Content-Type": "text/plain"
+        },
+        "transformers" : [ "response-template", "foo-transformer" ]
+    }
+}