private void smokeTestDoc(Document doc) {
        FieldValue boolField = doc.getFieldValue(doc.getField("flag"));
        assertSame(BoolFieldValue.class, boolField.getClass());
        assertTrue((Boolean)boolField.getWrappedValue());

        FieldValue stringField = doc.getFieldValue(doc.getField("nalle"));
        assertSame(StringFieldValue.class, stringField.getClass());
        assertEquals("bamse", ((StringFieldValue) stringField).getString());
    }
Basic test of JSON streams to Vespa document instances.

@author Steinar Knutsen
@author bratseth
document/src/test/java/com/yahoo/document/json/JsonReaderTestCase.java