Add base test class for JAR archivers

We're going to add Archiver implementation that could be used
for both regular and modular JAR archives. This base test class is
going to be useful to reuse tests between it and the existing
JarArchiver.

Author: plamentotev

src/test/java/org/codehaus/plexus/archiver/jar/BaseJarArchiverTest.java

@@ -0,0 +1,71 @@
+/**
+ *
+ * Copyright 2018 The Apache Software Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.codehaus.plexus.archiver.jar;
+
+import org.codehaus.plexus.archiver.ArchiverException;
+import org.codehaus.plexus.util.IOUtil;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+public abstract class BaseJarArchiverTest
+{
+
+    /*
+     * Verify that the JarArchiver implementation
+     * could create basic JAR file
+     */
+    @Test
+    public void testCreateJar()
+        throws IOException, ArchiverException
+    {
+        File jarFile = new File( "target/output/testJar.jar" );
+        jarFile.delete();
+
+        JarArchiver archiver = getJarArchiver();
+        archiver.setDestFile( jarFile );
+        archiver.addDirectory( new File( "src/test/resources/java-classes" ) );
+
+        archiver.createArchive();
+
+        // verify that the JAR file is created and contains the expected files
+        try ( ZipFile resultingArchive = new ZipFile( jarFile ) )
+        {
+            // verify that the JAR file contains manifest file
+            assertNotNull( resultingArchive.getEntry( "META-INF/MANIFEST.MF" )  );
+
+            // verify the JAR contains the class and it is not corrupted
+            ZipEntry classFileEntry = resultingArchive.getEntry( "com/example/app/Main.class" );
+            InputStream resultingClassFile = resultingArchive.getInputStream( classFileEntry );
+            InputStream originalClassFile =
+                new FileInputStream( "src/test/resources/java-classes/com/example/app/Main.class" );
+
+            assertTrue( IOUtil.contentEquals( originalClassFile, resultingClassFile ) );
+        }
+    }
+
+    protected abstract JarArchiver getJarArchiver();
+
+}

src/test/java/org/codehaus/plexus/archiver/jar/JarArchiverTest.java

@@ -5,19 +5,20 @@
 import java.io.IOException;
 import java.util.Random;
 import org.codehaus.plexus.archiver.ArchiverException;
-import junit.framework.TestCase;
+import org.junit.Test;
 
 public class JarArchiverTest
-    extends TestCase
+    extends BaseJarArchiverTest
 {
 
+    @Test
     public void testCreateManifestOnlyJar()
         throws IOException, ManifestException, ArchiverException
     {
         File jarFile = File.createTempFile( "JarArchiverTest.", ".jar" );
         jarFile.deleteOnExit();
 
-        JarArchiver archiver = new JarArchiver();
+        JarArchiver archiver = getJarArchiver();
         archiver.setDestFile( jarFile );
 
         Manifest manifest = new Manifest();
@@ -30,18 +31,20 @@ public void testCreateManifestOnlyJar()
         archiver.createArchive();
     }
 
+    @Test
     public void testNonCompressed()
         throws IOException, ManifestException, ArchiverException
     {
         File jarFile = new File( "target/output/jarArchiveNonCompressed.jar" );
 
-        JarArchiver archiver = new JarArchiver();
+        JarArchiver archiver = getJarArchiver();
         archiver.setDestFile( jarFile );
         archiver.setCompress( false );
         archiver.addDirectory( new File( "src/test/resources/mjar179" ) );
         archiver.createArchive();
     }
 
+    @Test
     public void testVeryLargeJar()
         throws IOException, ManifestException, ArchiverException
     {
@@ -65,10 +68,15 @@ public void testVeryLargeJar()
 
         File jarFile = new File( "target/output/veryLargeJar.jar" );
 
-        JarArchiver archiver = new JarArchiver();
+        JarArchiver archiver = getJarArchiver();
         archiver.setDestFile( jarFile );
         archiver.addDirectory( tmpDir );
         archiver.createArchive();
     }
 
+    @Override
+    protected JarArchiver getJarArchiver()
+    {
+        return new JarArchiver();
+    }
 }

src/test/resources/java-classes/com/example/app/Main.class

@@ -0,0 +1 @@
+ley=value

src/test/resources/java-classes/com/example/resources/test.properties

@@ -0,0 +1,2 @@
+This is the source code for the Java classes
+inside `java-classes` directory.

src/test/resources/java-src/REAMDE.md

@@ -0,0 +1,10 @@
+package com.example.app;
+
+public class Main
+{
+
+    public static void main( String[] args )
+    {
+        System.out.println( "Hello from Main" );
+    }
+}