Add failing test for #4656 (#5147)

Author: cowtowncoder

src/test/java/com/fasterxml/jackson/databind/tofix/DeserializationProblemHandler4656Test.java

@@ -0,0 +1,61 @@
+package com.fasterxml.jackson.databind.tofix;
+
+import java.io.IOException;
+
+import org.junit.jupiter.api.Test;
+
+import com.fasterxml.jackson.core.*;
+
+import com.fasterxml.jackson.databind.*;
+import com.fasterxml.jackson.databind.deser.DeserializationProblemHandler;
+import com.fasterxml.jackson.databind.json.JsonMapper;
+import com.fasterxml.jackson.databind.testutil.DatabindTestUtil;
+import com.fasterxml.jackson.databind.testutil.failure.JacksonTestFailureExpected;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+public class DeserializationProblemHandler4656Test extends DatabindTestUtil
+{
+    // For [databind#4656]
+    static class Person4656 {
+        public String id;
+        public String name;
+        public Long age;
+    }
+
+    static class ProblemHandler4656 extends DeserializationProblemHandler
+    {
+        protected static final String NUMBER_LONG_KEY = "$numberLong";
+    
+        @Override
+        public Object handleUnexpectedToken(DeserializationContext ctxt, JavaType targetType,
+                JsonToken t, JsonParser p, String failureMsg) throws IOException
+        {
+            if (targetType.getRawClass().equals(Long.class) && t == JsonToken.START_OBJECT) {
+                JsonNode tree = p.readValueAsTree();
+                if (tree.get(NUMBER_LONG_KEY) != null) {
+                    try {
+                        return Long.parseLong(tree.get(NUMBER_LONG_KEY).asText());
+                    } catch (NumberFormatException e) { }
+                }
+            }
+            return NOT_HANDLED;
+        }
+    }
+
+    // For [databind#4656]
+    @JacksonTestFailureExpected
+    @Test
+    public void testIssue4656() throws Exception {
+        ObjectMapper mapper = JsonMapper.builder()
+                .addHandler(new ProblemHandler4656())
+                .build();
+        final String json = "{\"id\":  \"12ab\", \"name\": \"Bob\", \"age\": {\"$numberLong\": \"10\"}}";
+        Person4656 person = mapper.readValue(json, Person4656.class);
+        assertNotNull(person);
+        assertEquals("12ab", person.id);
+        assertEquals("Bob", person.name);
+        assertEquals(10L, person.age);
+    }
+}