Fail if duplicate features are detected. Closes cucumber#165.

History.md

@@ -1,3 +1,7 @@
+## In Git
+
+* [Core] Fail if duplicate features are detected ([#165](https://github.com/cucumber/cucumber-jvm/issues/165) Aslak Hellesøy)
+
 ## [1.0.0.RC14](https://github.com/cucumber/cucumber-jvm/compare/v1.0.0.RC13...v1.0.0.RC14)
 
 * [Core] HTML formatter produces invalid page if no features ([#191](https://github.com/cucumber/cucumber-jvm/issues/191) Paolo Ambrosio)

core/src/main/java/cucumber/runtime/FeatureBuilder.java

@@ -16,15 +16,29 @@
 
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.math.BigInteger;
+import java.nio.charset.Charset;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 public class FeatureBuilder implements Formatter {
+    private static final Charset UTF8 = Charset.forName("UTF-8");
     private final List<CucumberFeature> cucumberFeatures;
+    private final MessageDigest md5;
     private CucumberFeature currentCucumberFeature;
     private String uri;
+    private Map<String, String> pathsByChecksum = new HashMap<String, String>();
 
     public FeatureBuilder(List<CucumberFeature> cucumberFeatures) {
         this.cucumberFeatures = cucumberFeatures;
+        try {
+            this.md5 = MessageDigest.getInstance("MD5");
+        } catch (NoSuchAlgorithmException e) {
+            throw new CucumberException(e);
+        }
     }
 
     @Override
@@ -86,6 +100,14 @@ public void parse(Resource resource, List<Object> filters) {
         }
         Parser parser = new Parser(formatter);
         String gherkin = read(resource);
+
+        String checksum = checksum(gherkin);
+        String path = pathsByChecksum.get(checksum);
+        if(path != null) {
+            throw new CucumberException(String.format("Found the same source in %s and %s", path, resource.getPath()));
+        }
+        pathsByChecksum.put(checksum, resource.getPath());
+
         parser.parse(gherkin, resource.getPath(), 0);
         I18n i18n = parser.getI18nLanguage();
         if (currentCucumberFeature != null) {
@@ -95,6 +117,10 @@ public void parse(Resource resource, List<Object> filters) {
         }
     }
 
+    private String checksum(String gherkin) {
+        return new BigInteger(1, md5.digest(gherkin.getBytes(UTF8))).toString(16);
+    }
+
     private String read(Resource resource) {
         try {
             return FixJava.readReader(new InputStreamReader(resource.getInputStream(), "UTF-8"));

core/src/test/java/cucumber/runtime/FeatureBuilderTest.java

@@ -0,0 +1,30 @@
+package cucumber.runtime;
+
+import cucumber.io.Resource;
+import cucumber.runtime.model.CucumberFeature;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+import static java.util.Collections.emptyList;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class FeatureBuilderTest {
+    @Test(expected = CucumberException.class)
+    public void detects_duplicate_features() throws IOException {
+        List<CucumberFeature> fearures = new ArrayList<CucumberFeature>();
+        FeatureBuilder builder = new FeatureBuilder(fearures);
+        Resource resource = mock(Resource.class);
+        when(resource.getPath()).thenReturn("foo.feature");
+        ByteArrayInputStream firstFeature = new ByteArrayInputStream("Feature: foo".getBytes("UTF-8"));
+        ByteArrayInputStream secondFeature = new ByteArrayInputStream("Feature: foo".getBytes("UTF-8"));
+        when(resource.getInputStream()).thenReturn(firstFeature, secondFeature);
+        builder.parse(resource, emptyList());
+        builder.parse(resource, emptyList());
+    }
+
+}