JUnit Document Subset Canonicalization (using XOM 1.1)

    public void assertCanonicalEquals(Document expected, Document actual, String xpath) {
        
        ByteArrayOutputStream expectedBytes = new ByteArrayOutputStream();
        ByteArrayOutputStream actualBytes = new ByteArrayOutputStream();
        
        try {
            Canonicalizer expectedCanonicalizer = new Canonicalizer(expectedBytes);
            Nodes expectedNodes = expected.query(xpath);
            expectedCanonicalizer.write(expectedNodes);
            byte[] expectedArray = expectedBytes.toByteArray();
        
            Canonicalizer actualCanonicalizer = new Canonicalizer(actualBytes);
            Nodes actualNodes = actual.query(xpath);
            actualCanonicalizer.write(actualNodes);
            byte[] actualArray = actualBytes.toByteArray();
        
            assertEquals(expectedArray.length, actualArray.length);
            for (int i = 0; i < expectedArray.length; i++) {
                assertEquals(expectedArray[i], actualArray[i]);
            }
        }
        catch (IOException ex) {
            fail("IOException while canonicalizing");
        }        
        
    }