@Test
    public final void readSingleDocumentUpdate() throws IOException {
        DocumentUpdate doc = parseUpdate("""
                                         {
                                           "update": "id:unittest:smoke::whee",
                                           "fields": {
                                             "something": {
                                               "assign": "orOther"
                                             }
                                           }
                                         }
                                         """);
        FieldUpdate f = doc.getFieldUpdate("something");
        assertEquals(1, f.size());
        assertTrue(f.getValueUpdate(0) instanceof AssignValueUpdate);
        assertEquals(new StringFieldValue("orOther"), f.getValueUpdate(0).getValue());
    }
Basic test of JSON streams to Vespa document instances.

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