Parts of a string calculator

CalculatorFactory.java

package ocpCalc;

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

public class CalculatorFactory {

	public Calculator create() {
		BinaryInfixParser arithmeticParser = new BinaryInfixParser(operators());
		Parser parser = new EmptyStringParser(arithmeticParser);
		return new Calculator(parser);
	}
	
	private Map<String, Operator> operators() {
		Map<String, Operator> operators = new HashMap<String, Operator>();
		operators.put("+", new Addition());
		operators.put("-", new Subtraction());
		return operators;
	}

}

OcpCalculatorTester.java

package ocpCalc;

import static org.junit.Assert.*;

import org.junit.Before;
import org.junit.Test;

public class OcpCalculatorTester {

	private Calculator calc;

	@Before
	public void setUp() throws Exception {
		calc = new CalculatorFactory().create();
	}
	
	@Test
	public void simpleAddition() {
		assertEquals(9, calc.eval("6 + 3"));
	}
	
	@Test
	public void additionWithIntegers() {
		assertEquals(46, calc.eval("12 + 34"));
	}
	
	@Test
	public void simpleSubtraction() {
		assertEquals(3, calc.eval("6 - 3"));
	}
	
	@Test
	public void emptyStringIsZero() {
		assertEquals(0, calc.eval("   "));
	}

//	@Test
//	public void integerValue() {
//		assertEquals(234, calc.eval("234"));
//	}

}