Delete only valid mappings before generating stubs at runtime (#1547)

* Delete only valid mappings before generating stubs at runtime

Improvements over the changes in 6d44c54c. We now only delete files
which contain valid mappings before generating stubs at runtime. This
way we ensure that we actually use the newly generated stubs, but still
are able to keep additional files around to be included via
`body(file(...))`.

* Incorporated PR feedback

- Removed HttpServerStubFactory
- Use SpringFactorieLoader to load HttpServerStub implementations
- Added tests for WireMockHttpServerStub#isAccepted(File)

spring-cloud-contract-stub-runner/src/main/java/org/springframework/cloud/contract/stubrunner/StubRunnerFactory.java

@@ -18,18 +18,25 @@ package org.springframework.cloud.contract.stubrunner;
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.attribute.BasicFileAttributes;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.List;
 import java.util.Map;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import org.springframework.cloud.contract.stubrunner.provider.wiremock.WireMockHttpServerStub;
 import org.springframework.cloud.contract.verifier.converter.RecursiveFilesConverter;
 import org.springframework.cloud.contract.verifier.messaging.MessageVerifier;
 import org.springframework.core.io.Resource;
+import org.springframework.core.io.support.SpringFactoriesLoader;
 
 /**
  * Factory of StubRunners. Basing on the options and passed collaborators downloads the
@@ -88,6 +95,7 @@ class StubRunnerFactory {
 	}
 
 	private void generateMappingsAtRuntime(Path path) {
+		removeCurrentMappings(path);
 		generateNewMappings(path);
 	}
 
@@ -106,6 +114,46 @@ class StubRunnerFactory {
 		return path;
 	}
 
+	private void removeCurrentMappings(Path path) {
+
+		List<HttpServerStub> httpServerStubs = SpringFactoriesLoader
+				.loadFactories(HttpServerStub.class, null);
+		if (httpServerStubs.isEmpty()) {
+			httpServerStubs.add(new WireMockHttpServerStub());
+		}
+
+		try {
+			Files.walkFileTree(path, new SimpleFileVisitor<Path>() {
+
+				private final Log log = LogFactory.getLog(StubRunnerFactory.class);
+
+				@Override
+				public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
+
+					if (httpServerStubs.stream()
+							.anyMatch(h -> h.isAccepted(file.toFile()))) {
+						if (log.isDebugEnabled()) {
+							log.debug("Deleting file [" + file.toString()
+									+ "] since it contains a valid mapping.");
+						}
+
+						try {
+							Files.delete(file);
+						}
+						catch (IOException ex) {
+							log.warn("Failed to delete file [" + file.toString() + "]",
+									ex);
+						}
+					}
+					return FileVisitResult.CONTINUE;
+				}
+			});
+		}
+		catch (IOException ex) {
+			log.warn("Exception occurred while trying to delete mappings", ex);
+		}
+	}
+
 	private void generateNewMappings(Path path) {
 		File unpackedLocation = path.toFile();
 		RecursiveFilesConverter converter = new RecursiveFilesConverter(

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

@@ -30,6 +30,7 @@ import java.util.concurrent.ConcurrentHashMap;
 
 import com.github.tomakehurst.wiremock.WireMockServer;
 import com.github.tomakehurst.wiremock.client.WireMock;
+import com.github.tomakehurst.wiremock.common.JsonException;
 import com.github.tomakehurst.wiremock.common.Slf4jNotifier;
 import com.github.tomakehurst.wiremock.core.WireMockConfiguration;
 import com.github.tomakehurst.wiremock.extension.Extension;
@@ -237,7 +238,17 @@ public class WireMockHttpServerStub implements HttpServerStub {
 
 	@Override
 	public boolean isAccepted(File file) {
-		return file.getName().endsWith(".json");
+		return file.getName().endsWith(".json") && validMapping(file);
+	}
+
+	private boolean validMapping(File file) {
+		try {
+			getMapping(file);
+			return true;
+		}
+		catch (IllegalStateException e) {
+			return false;
+		}
 	}
 
 	StubMapping getMapping(File file) {
@@ -245,7 +256,7 @@ public class WireMockHttpServerStub implements HttpServerStub {
 			return StubMapping.buildFrom(
 					StreamUtils.copyToString(stream, Charset.forName("UTF-8")));
 		}
-		catch (IOException e) {
+		catch (IOException | JsonException e) {
 			throw new IllegalStateException("Cannot read file", e);
 		}
 	}

spring-cloud-contract-stub-runner/src/test/groovy/org/springframework/cloud/contract/stubrunner/StubRunnerSpec.groovy

@@ -57,7 +57,6 @@ class StubRunnerSpec extends Specification {
 			runner.close()
 	}
 
-
 	def 'should generate stubs at runtime'() {
 		given:
 			Arguments args = argumentsWithGenerateStubs()

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

@@ -30,6 +30,9 @@ import org.springframework.web.client.RestTemplate
 class WireMockHttpServerStubSpec extends Specification {
 	public static
 	final File MAPPING_DESCRIPTOR = new File('src/test/resources/transformers.json')
+	public static final File ARBITRARY_JSON = new File('src/test/resources/sample_response.json')
+	public static final File PDF = new File('src/test/resources/request.pdf')
+	public static final File BROKEN_MAPPING = new File('src/test/resources/broken.json')
 
 	@Rule
 	OutputCaptureRule capture = new OutputCaptureRule()
@@ -76,4 +79,40 @@ class WireMockHttpServerStubSpec extends Specification {
 		cleanup:
 			mappingDescriptor?.stop()
 	}
+
+	def 'should accept a valid mapping'() {
+		given:
+			WireMockHttpServerStub httpServerStub = new WireMockHttpServerStub()
+		when:
+			boolean accepted = httpServerStub.isAccepted(MAPPING_DESCRIPTOR)
+		then:
+			accepted
+	}
+
+	def 'should not accept an arbitrary JSON file'() {
+		given:
+			WireMockHttpServerStub httpServerStub = new WireMockHttpServerStub()
+		when:
+			boolean accepted = httpServerStub.isAccepted(ARBITRARY_JSON)
+		then:
+			!accepted
+	}
+
+	def 'should not accept a broken mapping file'() {
+		given:
+			WireMockHttpServerStub httpServerStub = new WireMockHttpServerStub()
+		when:
+			boolean accepted = httpServerStub.isAccepted(BROKEN_MAPPING)
+		then:
+			!accepted
+	}
+
+	def 'should not accept a non-JSON file'() {
+		given:
+			WireMockHttpServerStub httpServerStub = new WireMockHttpServerStub()
+		when:
+			boolean accepted = httpServerStub.isAccepted(PDF)
+		then:
+			!accepted
+	}
 }

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

@@ -0,0 +1,12 @@
+[
+  {
+    "id": "1",
+    "firstname": "John",
+    "name": "Doe"
+  },
+  {
+    "id": "2",
+    "firstname": "Lisa",
+    "name": "Smith"
+  }
+]

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

@@ -0,0 +1,7 @@
+{
+  "request": {
+    "method": "GET",
+    "url": "/ping"
+  },
+  "response": {
+    "status": 200,