Mocking Unmarshaller
<p>I am writing a <code>JUnit</code> for a method which unmarshalling an <code>Object</code>. It is throwing <code>IllegalArgumentException</code> while unmarshalling the Object.I cannot post the entire method.</p>

<p>Method under test</p>

<pre><code>public void filter(ClientRequestContext requestContext, ClientResponseContext responseContext) throws IOException {
    MultivaluedMap&lt;String, String&gt; headers = responseContext.getHeaders();
    String contentType = headers.getFirst( CONTENT_TYPE_HEADER );

    if( contentType != null &amp;&amp; contentType.startsWith( TEXT_XML ) ) {
        if( 200 == responseContext.getStatus() ) {
            if( requestContext.getUri().toString().contains( "Policy/Retrieve" ) ) {
                try {
                    GetPolicyResponse p = (GetPolicyResponse)EISClientJAXBContextFactory.getUnmarshaller( GetPolicyResponse.class ).unmarshal( responseContext.getEntityStream() );

}
</code></pre>

<p>While debugging I found that <code>is</code> is null but I am passing <code>inputStream</code></p>

<pre><code>public final Object unmarshal( java.io.InputStream is )
    throws JAXBException {

    if( is == null ) {
        throw new IllegalArgumentException(
            Messages.format( Messages.MUST_NOT_BE_NULL, "is" ) );
    }

    InputSource isrc = new InputSource( is );
    return unmarshal( isrc );
}
</code></pre>

<p>JUnit</p>

<pre><code>@Test
public void testPersonalAutoDriver() throws Exception {
 ClientRequestContext requestContext = mock(ClientRequestContext.class);
    ClientResponseContext responseContext = mock(ClientResponseContext.class);
    MultivaluedMap&lt;String, String&gt; headers = mock(MultivaluedMap.class);
    URI uri = new URI("Policy/Retrieve");
    Unmarshaller unmarshaller = mock(Unmarshaller.class);

    when( responseContext.getHeaders() ).thenReturn( headers );
    when( headers.getFirst(Mockito.eq( "Content-Type" )) ).thenReturn( "text/xml" );
    when( responseContext.getStatus() ).thenReturn( 200 );
    when( requestContext.getUri()).thenReturn(uri);

    JAXBContext context = JAXBContext.newInstance(GetPolicyResponse.class);
    Marshaller marshaller = context.createMarshaller();

    Policy policy = new Policy();
    policy.setPolicyType( PolicyTypeEnum.PERSONAL_AUTO );

    GetPolicyResponse policyResponse = new GetPolicyResponse();
    policyResponse.setPolicy(policy);

    StringWriter writer = new StringWriter();
    marshaller.marshal( policyResponse, writer );
    System.out.println( "**** Object Marshalled Successfully ****" );

    InputStream inputStream = new ByteArrayInputStream(writer.toString().getBytes());
    when(unmarshaller.unmarshal(inputStream)).thenReturn(policyResponse);

//  EISClientJAXBContextFactory.getUnmarshaller( GetPolicyResponse.class );
//  Unmarshaller unmarshaller = context.createUnmarshaller();
//  GetPolicyResponse policyResponse2 = ( GetPolicyResponse ) unmarshaller.unmarshal( inputStream );

//  assertNotNull(policyResponse2);

    filter.filter( requestContext, responseContext );
    System.out.println( "**** Object Unmarshalled Successfully ****" );
}
</code></pre>