TestMissingNode.java

package com.fasterxml.jackson.databind.node;

import java.io.StringReader;
import java.util.Iterator;

import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.databind.JsonNode;

public class TestMissingNode extends NodeTestBase
{
    public void testMissing()
    {
        MissingNode n = MissingNode.getInstance();
        assertTrue(n.isMissingNode());
        assertEquals(JsonToken.NOT_AVAILABLE, n.asToken());
        assertEquals("", n.asText());
        assertStandardEquals(n);
        assertEquals("", n.toString());

        assertNodeNumbersForNonNumeric(n);

        assertTrue(n.asBoolean(true));
        assertEquals(4, n.asInt(4));
        assertEquals(5L, n.asLong(5));
        assertEquals(0.25, n.asDouble(0.25));

        assertEquals("foo", n.asText("foo"));
    }

    /**
     * Let's also verify behavior of "MissingNode" -- one needs to be able
     * to traverse such bogus nodes with appropriate methods.
     */
    @SuppressWarnings("unused")
    public void testMissingViaMapper() throws Exception
    {
        String JSON = "[ { }, [ ] ]";
        JsonNode result = objectMapper().readTree(new StringReader(JSON));

        assertTrue(result.isContainerNode());
        assertTrue(result.isArray());
        assertEquals(2, result.size());

        int count = 0;
        for (JsonNode node : result) {
            ++count;
        }
        assertEquals(2, count);

        Iterator<JsonNode> it = result.iterator();

        JsonNode onode = it.next();
        assertTrue(onode.isContainerNode());
        assertTrue(onode.isObject());
        assertEquals(0, onode.size());
        assertFalse(onode.isMissingNode()); // real node
        assertNull(onode.textValue());

        // how about dereferencing?
        assertNull(onode.get(0));
        JsonNode dummyNode = onode.path(0);
        assertNotNull(dummyNode);
        assertTrue(dummyNode.isMissingNode());
        assertNull(dummyNode.get(3));
        assertNull(dummyNode.get("whatever"));
        JsonNode dummyNode2 = dummyNode.path(98);
        assertNotNull(dummyNode2);
        assertTrue(dummyNode2.isMissingNode());
        JsonNode dummyNode3 = dummyNode.path("field");
        assertNotNull(dummyNode3);
        assertTrue(dummyNode3.isMissingNode());

        // and same for the array node

        JsonNode anode = it.next();
        assertTrue(anode.isContainerNode());
        assertTrue(anode.isArray());
        assertFalse(anode.isMissingNode()); // real node
        assertEquals(0, anode.size());

        assertNull(anode.get(0));
        dummyNode = anode.path(0);
        assertNotNull(dummyNode);
        assertTrue(dummyNode.isMissingNode());
        assertNull(dummyNode.get(0));
        assertNull(dummyNode.get("myfield"));
        dummyNode2 = dummyNode.path(98);
        assertNotNull(dummyNode2);
        assertTrue(dummyNode2.isMissingNode());
        dummyNode3 = dummyNode.path("f");
        assertNotNull(dummyNode3);
        assertTrue(dummyNode3.isMissingNode());
    }
}