Throw specific exception when creating empty single file archive

Currently archivers that accept single file (like BZip2Archiver)
will throw `NoSuchElementException`.
Modify them to throw `EmptyArchiveException` so they are
consistent with `DirectoryArchiver`, `TarArchiver` and `ZipArchiver`.

Author: plamentotev

src/main/java/org/codehaus/plexus/archiver/bzip2/BZip2Archiver.java

@@ -21,6 +21,7 @@
 import org.codehaus.plexus.archiver.ArchiveEntry;
 import org.codehaus.plexus.archiver.ArchiverException;
 import org.codehaus.plexus.archiver.ResourceIterator;
+import org.codehaus.plexus.archiver.exceptions.EmptyArchiveException;
 
 public class BZip2Archiver
     extends AbstractArchiver
@@ -38,6 +39,10 @@ public void execute()
         }
 
         ResourceIterator iter = getResources();
+        if ( !iter.hasNext() )
+        {
+            throw new EmptyArchiveException( "Archive cannot be empty." );
+        }
         ArchiveEntry entry = iter.next();
         if ( iter.hasNext() )
         {

src/main/java/org/codehaus/plexus/archiver/gzip/GZipArchiver.java

@@ -21,6 +21,7 @@
 import org.codehaus.plexus.archiver.ArchiveEntry;
 import org.codehaus.plexus.archiver.ArchiverException;
 import org.codehaus.plexus.archiver.ResourceIterator;
+import org.codehaus.plexus.archiver.exceptions.EmptyArchiveException;
 
 public class GZipArchiver
     extends AbstractArchiver
@@ -38,6 +39,10 @@ protected void execute()
         }
 
         ResourceIterator iter = getResources();
+        if ( !iter.hasNext() )
+        {
+            throw new EmptyArchiveException( "Archive cannot be empty." );
+        }
         ArchiveEntry entry = iter.next();
         if ( iter.hasNext() )
         {

src/main/java/org/codehaus/plexus/archiver/snappy/SnappyArchiver.java

@@ -21,6 +21,7 @@
 import org.codehaus.plexus.archiver.ArchiveEntry;
 import org.codehaus.plexus.archiver.ArchiverException;
 import org.codehaus.plexus.archiver.ResourceIterator;
+import org.codehaus.plexus.archiver.exceptions.EmptyArchiveException;
 
 /**
  * Snappy archiver.
@@ -41,6 +42,10 @@ public void execute()
         }
 
         ResourceIterator iter = getResources();
+        if ( !iter.hasNext() )
+        {
+            throw new EmptyArchiveException( "Archive cannot be empty." );
+        }
         ArchiveEntry entry = iter.next();
         if ( iter.hasNext() )
         {

src/main/java/org/codehaus/plexus/archiver/xz/XZArchiver.java

@@ -20,6 +20,7 @@
 import org.codehaus.plexus.archiver.ArchiveEntry;
 import org.codehaus.plexus.archiver.ArchiverException;
 import org.codehaus.plexus.archiver.ResourceIterator;
+import org.codehaus.plexus.archiver.exceptions.EmptyArchiveException;
 
 /**
  * @author philiplourandos
@@ -43,6 +44,10 @@ protected void execute() throws ArchiverException, IOException
         }
 
         ResourceIterator iter = getResources();
+        if ( !iter.hasNext() )
+        {
+            throw new EmptyArchiveException( "Archive cannot be empty." );
+        }
         ArchiveEntry entry = iter.next();
         if ( iter.hasNext() )
         {

src/test/java/org/codehaus/plexus/archiver/bzip2/BZip2ArchiverTest.java

@@ -31,6 +31,7 @@
 import java.util.zip.ZipFile;
 import org.codehaus.plexus.archiver.Archiver;
 import org.codehaus.plexus.archiver.BasePlexusArchiverTest;
+import org.codehaus.plexus.archiver.exceptions.EmptyArchiveException;
 import org.codehaus.plexus.archiver.zip.ZipArchiver;
 import org.codehaus.plexus.util.FileUtils;
 import org.codehaus.plexus.util.IOUtil;
@@ -57,6 +58,22 @@ public void testCreateArchive()
         archiver.createArchive();
     }
 
+    public void testCreateEmptyArchive()
+        throws Exception
+    {
+        BZip2Archiver archiver = (BZip2Archiver) lookup( Archiver.ROLE, "bzip2" );
+        archiver.setDestFile( getTestFile( "target/output/empty.bz2" ) );
+        try
+        {
+            archiver.createArchive();
+
+            fail( "Creating empty archive should throw EmptyArchiveException" );
+        }
+        catch ( EmptyArchiveException ignore )
+        {
+        }
+    }
+
     public void testCreateResourceCollection()
         throws Exception
     {

src/test/java/org/codehaus/plexus/archiver/gzip/GZipArchiverTest.java

@@ -31,6 +31,7 @@
 import java.util.zip.ZipFile;
 import org.codehaus.plexus.archiver.Archiver;
 import org.codehaus.plexus.archiver.BasePlexusArchiverTest;
+import org.codehaus.plexus.archiver.exceptions.EmptyArchiveException;
 import org.codehaus.plexus.archiver.zip.ZipArchiver;
 import org.codehaus.plexus.util.FileUtils;
 import org.codehaus.plexus.util.IOUtil;
@@ -57,6 +58,23 @@ public void testCreateArchive()
         archiver.createArchive();
     }
 
+
+    public void testCreateEmptyArchive()
+        throws Exception
+    {
+        GZipArchiver archiver = (GZipArchiver) lookup( Archiver.ROLE, "gzip" );
+        archiver.setDestFile( getTestFile( "target/output/empty.gz" ) );
+        try
+        {
+            archiver.createArchive();
+
+            fail( "Creating empty archive should throw EmptyArchiveException" );
+        }
+        catch ( EmptyArchiveException ignore )
+        {
+        }
+    }
+
     public void testCreateResourceCollection()
         throws Exception
     {

src/test/java/org/codehaus/plexus/archiver/snappy/SnappyArchiverTest.java

@@ -31,6 +31,7 @@
 import java.util.zip.ZipFile;
 import org.codehaus.plexus.archiver.Archiver;
 import org.codehaus.plexus.archiver.BasePlexusArchiverTest;
+import org.codehaus.plexus.archiver.exceptions.EmptyArchiveException;
 import org.codehaus.plexus.archiver.zip.ZipArchiver;
 import org.codehaus.plexus.util.FileUtils;
 import org.codehaus.plexus.util.IOUtil;
@@ -57,6 +58,22 @@ public void testCreateArchive()
         archiver.createArchive();
     }
 
+    public void testCreateEmptyArchive()
+        throws Exception
+    {
+        SnappyArchiver archiver = (SnappyArchiver) lookup( Archiver.ROLE, "snappy" );
+        archiver.setDestFile( getTestFile( "target/output/empty.snappy" ) );
+        try
+        {
+            archiver.createArchive();
+
+            fail( "Creating empty archive should throw EmptyArchiveException" );
+        }
+        catch ( EmptyArchiveException ignore )
+        {
+        }
+    }
+
     public void testCreateResourceCollection()
         throws Exception
     {

src/test/java/org/codehaus/plexus/archiver/xz/XzArchiverTest.java

@@ -23,6 +23,7 @@
 import java.util.zip.ZipFile;
 import org.codehaus.plexus.archiver.Archiver;
 import org.codehaus.plexus.archiver.BasePlexusArchiverTest;
+import org.codehaus.plexus.archiver.exceptions.EmptyArchiveException;
 import org.codehaus.plexus.archiver.zip.ZipArchiver;
 import org.codehaus.plexus.util.FileUtils;
 import org.codehaus.plexus.util.IOUtil;
@@ -64,6 +65,22 @@ public void testCreateArchive()
         assertTrue( targetOutputFile.exists() );
     }
 
+    public void testCreateEmptyArchive()
+        throws Exception
+    {
+        XZArchiver archiver = (XZArchiver) lookup( Archiver.ROLE, "xz" );
+        archiver.setDestFile( getTestFile( "target/output/empty.xz" ) );
+        try
+        {
+            archiver.createArchive();
+
+            fail( "Creating empty archive should throw EmptyArchiveException" );
+        }
+        catch ( EmptyArchiveException ignore )
+        {
+        }
+    }
+
     public void testCreateResourceCollection() throws Exception
     {
         final File pomFile = new File( "pom.xml" );