Reproducible metadata

plexus-component-metadata/src/main/java/org/codehaus/plexus/metadata/DefaultMetadataGenerator.java

@@ -28,6 +28,7 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 
@@ -101,6 +102,15 @@ public void generateDescriptor( MetadataGenerationRequest request )
             }
         }
 
+        // Sort the descriptors by key to make the output reproducible
+        Collections.sort( descriptors, new Comparator<ComponentDescriptor>()
+        {
+            public int compare( ComponentDescriptor d1, ComponentDescriptor d2 )
+            {
+                return d1.getHumanReadableKey().compareTo( d2.getHumanReadableKey() );
+            }
+        });
+
         List<File> componentDescriptors = new ArrayList<File>();        
 
         //

plexus-component-metadata/src/test/java/org/codehaus/plexus/metadata/DefaultComponentDescriptorWriterTest.java

@@ -16,7 +16,9 @@
 
 package org.codehaus.plexus.metadata;
 
+import java.io.File;
 import java.io.StringWriter;
+import java.util.Collections;
 import java.util.List;
 
 import org.codehaus.plexus.PlexusTestCase;
@@ -26,6 +28,12 @@
 import org.codehaus.plexus.component.repository.ComponentDescriptor;
 import org.codehaus.plexus.component.repository.io.PlexusTools;
 import org.codehaus.plexus.configuration.PlexusConfiguration;
+import org.codehaus.plexus.metadata.merge.ComponentsXmlMerger;
+import org.codehaus.plexus.metadata.merge.Merger;
+import org.codehaus.plexus.metadata.merge.PlexusXmlMerger;
+import org.jdom2.Document;
+import org.jdom2.Element;
+import org.jdom2.input.SAXBuilder;
 
 /**
  * Test for the {@link DefaultComponentDescriptorWriter} class.
@@ -96,4 +104,41 @@ public void testBasic() throws Exception {
         // TODO: Verify requirements and configuration too... but I'm too lazy for that right now
         //
     }
+
+    public void testComponentsOrder() throws Exception {
+        MetadataGenerator generator = (MetadataGenerator) lookup(MetadataGenerator.class);
+        assertNotNull(generator);
+
+        MetadataGenerationRequest request = new MetadataGenerationRequest();
+        request.sourceDirectories = Collections.singletonList("src/main/java");
+        request.classesDirectory = new File("target/classes");
+        request.outputFile = new File("target/test-classes/components-sorted.xml");
+        request.sourceEncoding = "UTF-8";
+        request.useContextClassLoader = true;
+
+        generator.generateDescriptor(request);
+
+        assertTrue("Descriptor not generated", request.outputFile.exists());
+
+        Document doc = new SAXBuilder().build(request.outputFile);
+
+        // check if the components are sorted by role+impl
+        List<Element> components = doc.getRootElement().getChild("components").getChildren();
+        assertEquals("Number of components", 5, components.size());
+
+        assertEquals("Component 1 role", ComponentDescriptorExtractor.class.getName(), components.get(0).getChild("role").getText());
+        assertEquals("Component 1 impl", ClassComponentDescriptorExtractor.class.getName(), components.get(0).getChild("implementation").getText());
+
+        assertEquals("Component 2 role", ComponentDescriptorExtractor.class.getName(), components.get(1).getChild("role").getText());
+        assertEquals("Component 2 impl", SourceComponentDescriptorExtractor.class.getName(), components.get(1).getChild("implementation").getText());
+
+        assertEquals("Component 3 role", MetadataGenerator.class.getName(), components.get(2).getChild("role").getText());
+        assertEquals("Component 3 impl", DefaultMetadataGenerator.class.getName(), components.get(2).getChild("implementation").getText());
+
+        assertEquals("Component 4 role", Merger.class.getName(), components.get(3).getChild("role").getText());
+        assertEquals("Component 4 impl", ComponentsXmlMerger.class.getName(), components.get(3).getChild("implementation").getText());
+
+        assertEquals("Component 5 role", Merger.class.getName(), components.get(4).getChild("role").getText());
+        assertEquals("Component 5 impl", PlexusXmlMerger.class.getName(), components.get(4).getChild("implementation").getText());
+    }
 }