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`.

This closes #64

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/dir/DirectoryArchiver.java

@@ -54,7 +54,7 @@ public void execute()
         final ResourceIterator iter = getResources();
         if ( !iter.hasNext() )
         {
-            throw new EmptyArchiveException( "You must set at least one file." );
+            throw new EmptyArchiveException( "archive cannot be empty" );
         }
 
         final File destDirectory = getDestFile();

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/tar/TarArchiver.java

@@ -111,7 +111,7 @@ protected void execute()
         ResourceIterator iter = getResources();
         if ( !iter.hasNext() )
         {
-            throw new EmptyArchiveException( "You must set at least one file." );
+            throw new EmptyArchiveException( "archive cannot be empty" );
         }
 
         File tarFile = getDestFile();

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/main/java/org/codehaus/plexus/archiver/zip/AbstractZipArchiver.java

@@ -255,7 +255,7 @@ private void createArchiveMain()
         ResourceIterator iter = getResources();
         if ( !iter.hasNext() && !hasVirtualFiles() )
         {
-            throw new EmptyArchiveException( "You must set at least one file." );
+            throw new EmptyArchiveException( "archive cannot be empty" );
         }
 
         zipFile = getDestFile();

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
     {