src/test/java/org/yaml/snakeyaml/types/NullTagTest.java

/**
 * Copyright (c) 2008-2013, http://www.snakeyaml.org
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.yaml.snakeyaml.types;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.yaml.snakeyaml.DumperOptions;
import org.yaml.snakeyaml.DumperOptions.FlowStyle;
import org.yaml.snakeyaml.Yaml;
import org.yaml.snakeyaml.nodes.Node;
import org.yaml.snakeyaml.nodes.Tag;
import org.yaml.snakeyaml.representer.Represent;
import org.yaml.snakeyaml.representer.Representer;

/**
 * @see http://yaml.org/type/null.html
 */
public class NullTagTest extends AbstractTest {

    public void testNull() {
        assertNull("Got: '" + load("---\n") + "'", load("---\n"));
        assertNull(load("---\n..."));
        assertNull(load("---\n...\n"));
        assertNull(load("\n"));
        assertNull(load(""));
        assertNull(load(" "));
        assertNull(load("~"));
        assertNull(load("---\n~"));
        assertNull(load("null"));
        assertNull(load("Null"));
        assertNull(load("NULL"));
        assertNull(getMapValue("empty:\n", "empty"));
        assertNull(getMapValue("canonical: ~", "canonical"));
        assertNull(getMapValue("english: null", "english"));
        assertNull(getMapValue("english: Null", "english"));
        assertNull(getMapValue("english: NULL", "english"));
        assertEquals("null key", getMapValue("~: null key\n", null));
    }

    @SuppressWarnings("unchecked")
    public void testSequenceNull() {
        String input = "---\n# This sequence has five\n# entries, two have values.\nsparse:\n  - ~\n  - 2nd entry\n  -\n  - 4th entry\n  - Null\n";
        List<String> parsed = (List<String>) getMapValue(input, "sparse");
        assertEquals(5, parsed.size());
        assertNull(parsed.get(0));
        assertEquals("2nd entry", parsed.get(1));
        assertNull("Got: '" + parsed.get(2) + "'", parsed.get(2));
        assertEquals("4th entry", parsed.get(3));
        assertNull(parsed.get(4));
    }

    public void testNullInMap() {
        String input = "key1: null\n~: value1";
        Map<String, Object> parsed = getMap(input);
        assertEquals(2, parsed.size());
        assertTrue(parsed.containsKey(null));
        Object value1 = parsed.get(null);
        assertEquals("value1", value1);
        //
        assertNull(parsed.get("key1"));
        //
        assertFalse(getMap("key2: value2").containsKey(null));
    }

    public void testNullShorthand() {
        assertNull(getMapValue("nothing: !!null null", "nothing"));
    }

    public void testNullTag() {
        assertNull(getMapValue("nothing: !<tag:yaml.org,2002:null> null", "nothing"));
    }

    public void testNullOut() {
        String output = dump(null);
        assertEquals("null\n", output);
    }

    public void testNullOutAsEmpty() {
        Yaml yaml = new Yaml(new NullRepresenter());
        String output = yaml.dump(null);
        assertEquals("", output);
    }

    /**
     * test flow style
     */
    public void testNullOutAsEmpty2() {
        Yaml yaml = new Yaml(new NullRepresenter());
        Map<String, String> map = new HashMap<String, String>();
        map.put("aaa", "foo");
        map.put("bbb", null);
        String output = yaml.dump(map);
        assertEquals("{aaa: foo, bbb: !!null ''}\n", output);
    }

    /**
     * test block style
     */
    public void testBoolOutAsEmpty3() {
        DumperOptions options = new DumperOptions();
        options.setDefaultFlowStyle(FlowStyle.BLOCK);
        Yaml yaml = new Yaml(new NullRepresenter(), options);
        Map<String, String> map = new HashMap<String, String>();
        map.put("aaa", "foo");
        map.put("bbb", null);
        String output = yaml.dump(map);
        assertEquals("aaa: foo\nbbb:\n", output);
    }

    private class NullRepresenter extends Representer {
        public NullRepresenter() {
            super();
            // null representer is exceptional and it is stored as an instance
            // variable.
            this.nullRepresenter = new RepresentNull();
        }

        private class RepresentNull implements Represent {
            public Node representData(Object data) {
                // possible values are here http://yaml.org/type/null.html
                return representScalar(Tag.NULL, "");
            }
        }
    }

    public void testNoAnchors() {
        List<String> list = new ArrayList<String>(3);
        list.add(null);
        list.add("value");
        list.add(null);
        Yaml yaml = new Yaml();
        String output = yaml.dump(list);
        assertEquals("Null values must not get anchors and aliases.", "[null, value, null]\n",
                output);
    }
}