src/test/java/com/fasterxml/jackson/databind/module/TestAbstractTypes.java

package com.fasterxml.jackson.databind.module;

import java.util.*;

import com.fasterxml.jackson.core.Version;
import com.fasterxml.jackson.databind.BaseMapTest;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.module.SimpleModule;

public class TestAbstractTypes extends BaseMapTest
{
    static class MyString implements CharSequence
    {
        protected String value;
        
        public MyString(String s) { value = s; }

        @Override
        public char charAt(int index) {
            return value.charAt(index);
        }

        @Override
        public int length() {
            return value.length();
        }

        @Override
        public CharSequence subSequence(int arg0, int arg1) { return this; }
    }

    public interface Abstract {
        public int getValue();
    }

    public static class AbstractImpl implements Abstract {
        @Override
        public int getValue() { return 3; }
    }

    /*
    /**********************************************************
    /* Test methods
    /**********************************************************
     */

    public void testCollectionDefaulting() throws Exception
    {
        ObjectMapper mapper = new ObjectMapper();
        SimpleModule mod = new SimpleModule("test", Version.unknownVersion());
        // let's ensure we get hierarchic mapping
        mod.addAbstractTypeMapping(Collection.class, List.class);
        mod.addAbstractTypeMapping(List.class, LinkedList.class);
        mapper.registerModule(mod);
        Collection<?> result = mapper.readValue("[]", Collection.class);
        assertEquals(LinkedList.class, result.getClass());
    }

    public void testMapDefaultingBasic() throws Exception
    {
        ObjectMapper mapper = new ObjectMapper();
        SimpleModule mod = new SimpleModule("test", Version.unknownVersion());
        // default is HashMap, so:
        mod.addAbstractTypeMapping(Map.class, TreeMap.class);
        mapper.registerModule(mod);
        Map<?,?> result = mapper.readValue("{}", Map.class);
        assertEquals(TreeMap.class, result.getClass());
    }

    // [databind#700]
    public void testDefaultingRecursive() throws Exception
    {
        ObjectMapper mapper = new ObjectMapper();
        SimpleModule mod = new SimpleModule("test", Version.unknownVersion());

        // defaults: LinkedHashMap, ArrayList
        mod.addAbstractTypeMapping(Map.class, TreeMap.class);
        mod.addAbstractTypeMapping(List.class, LinkedList.class);

        mapper.registerModule(mod);
        Object result;

        result = mapper.readValue("[ {} ]", Object.class);
        assertEquals(LinkedList.class, result.getClass());
        Object v = ((List<?>) result).get(0);
        assertNotNull(v);
        assertEquals(TreeMap.class, v.getClass());

        result = mapper.readValue("{ \"x\": [ 3 ] }", Object.class);
        assertEquals(TreeMap.class, result.getClass());
        Map<?,?> map = (Map<?,?>) result;
        assertEquals(1, map.size());
        v = map.get("x");
        assertNotNull(v);
        assertEquals(LinkedList.class, v.getClass());
        assertEquals(1, ((List<?>) v).size());
    }

    public void testInterfaceDefaulting() throws Exception
    {
        ObjectMapper mapper = new ObjectMapper();
        SimpleModule mod = new SimpleModule("test", Version.unknownVersion());
        // let's ensure we get hierarchic mapping
        mod.addAbstractTypeMapping(CharSequence.class, MyString.class);
        mapper.registerModule(mod);
        Object result = mapper.readValue(quote("abc"), CharSequence.class);
        assertEquals(MyString.class, result.getClass());
        assertEquals("abc", ((MyString) result).value);

        // and ditto for POJOs
        mod = new SimpleModule();
        mod.addAbstractTypeMapping(Abstract.class, AbstractImpl.class);
        mapper = new ObjectMapper()
                .registerModule(mod);
        Abstract a = mapper.readValue("{}", Abstract.class);
        assertNotNull(a);
    }
}