@Test
    public void test_tensor_add_update() {
        roundtripSerializeJsonAndMatch(inputJson(
                "{",
                "  'update': 'DOCUMENT_ID',",
                "  'fields': {",
                "    'sparse_tensor': {",
                "      'add': {",
                "        'cells': [",
                "          { 'address': { 'x': '0', 'y': '0' }, 'value': 2.0 },",
                "          { 'address': { 'x': '1', 'y': '2' }, 'value': 3.0 }",
                "        ]",
                "      }",
                "    }",
                "  }",
                "}"
        ));
    }
Tests roundtrip serialization (JSON -> DocumentUpdate -> Buffer -> DocumentUpdate -> JSON) of document updates.

@author Vegard Sjonfjell
document/src/test/java/com/yahoo/document/json/DocumentUpdateJsonSerializerTest.java