Scope object for Tina

Scope.java

package com.github.mustachejava.util;

import java.util.HashMap;
import java.util.concurrent.ExecutionException;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

import com.github.mustachejava.Binding;
import com.github.mustachejava.MustacheException;
import com.github.mustachejava.reflect.SimpleObjectHandler;

public class Scope extends HashMap<String, Object> {
  private static final SimpleObjectHandler oh = new SimpleObjectHandler();
  private static final LoadingCache<String, Binding> CACHE = CacheBuilder.newBuilder().build(new CacheLoader<String, Binding>() {
    @Override
    public Binding load(String key) throws Exception {
      return oh.createBinding(key, null, null);
    }
  });

  private Object[] wrapped;

  public Scope(Object wrapped) {
    this.wrapped = new Object[] { wrapped };
  }

  public Scope(Object... wrapped) {
    this.wrapped = wrapped;
  }

  public Object get(String key) {
    try {
      Binding binding = CACHE.get(key);
      Object o = binding.get(wrapped);
      if (o == null) {
        o = super.get(key);
      }
      return o;
    } catch (ExecutionException e) {
      throw new MustacheException("Failed to get key", e);
    }
  }
}

ScopeTest.java

package com.github.mustachejava.util;

import java.util.HashMap;
import java.util.Map;

import org.junit.Test;

import static junit.framework.Assert.assertEquals;
import static junit.framework.Assert.assertTrue;

public class ScopeTest {
  @Test
  public void testWithMap() {
    Map map = new HashMap();
    map.put("sam", "pullara");
    assertEquals("pullara", new Scope(map).get("sam"));
  }

  @Test
  public void testWithField() {
    Object o = new Object() {
      String sam = "pullara";
    };
    assertEquals("pullara", new Scope(o).get("sam"));
  }

  @Test
  public void testWithMethod() {
    Object o = new Object() {
      String sam() {
        return "pullara";
      }
    };
    assertEquals("pullara", new Scope(o).get("sam"));
  }

  @Test
  public void testWithProperty() {
    Object o = new Object() {
      String getSam() {
        return "pullara";
      }
      boolean isSet() {
        return true;
      }
    };
    assertEquals("pullara", new Scope(o).get("sam"));
    assertTrue((Boolean) new Scope(o).get("isSet"));
  }

  @Test
  public void testContexts() {
    Object o1 = new Object() {
      String sam = "pullara";
      String lucy = "pullara";
    };
    Object o2 = new Object() {
      String sam = "Pullara";
    };
    assertEquals("Pullara", new Scope(o1, o2).get("sam"));
    assertEquals("pullara", new Scope(o2, o1).get("sam"));
    assertEquals("pullara", new Scope(o1, o1).get("lucy"));
    assertEquals("pullara", new Scope(o2, o1).get("lucy"));
  }

}