Introduction
This is a complete, albeit simple, example using jMock. To get this running, you’ll need to do the following
- Use Java 5 or later
- Add JUnit 4 to your classpath
- Download jMock
- Extract the download and add the 4 jars into your classpath (note your version numbers might be different):
- jmock-2.0.0.jar
- jmock-junit4-2.0.0.jar
- hamcrest-api-1.0.jar
- hamcrest-library-1.0.jar
- Take each of the following files and add them into a project in your favorite IDE
WithdrawalTest.java
package com.objectmentor.jmock;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import junit.framework.JUnit4TestAdapter;
import org.jmock.Expectations;
import org.jmock.Mockery;
import org.jmock.integration.junit4.JMock;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
@RunWith(JMock.class)
public class WithdrawalTest {
public static junit.framework.Test suite() {
return new JUnit4TestAdapter(WithdrawalTest.class);
}
Withdrawal withdrawal;
Mockery context = new Mockery();
BankAccount account;
@Before
public void initialize() {
withdrawal = new Withdrawal();
withdrawal.setAmount(1500);
account = context.mock(BankAccount.class);
withdrawal.setAccount(account);
}
@Test
public void failExecutionIfBalanceInadequate() {
context.checking(new Expectations() {
{
one(account).getBalance();
will(returnValue(1000));
}
});
boolean exceptionThrown = false;
try {
withdrawal.execute();
} catch (InsufficientFunds e) {
// success
exceptionThrown = true;
}
assertTrue("Should have thrown: " + InsufficientFunds.class,
exceptionThrown);
}
@Test
public void executeWithdrawChangesBalanceAndSetsExecuted() {
context.checking(new Expectations() {
{
ignoring(account).getBalance();
will(returnValue(2500));
one(account).deduct(with(equal(1500)));
}
});
withdrawal.execute();
assertEquals(true, withdrawal.isExecuted());
}
@Test
public void methodThatWeExpectWillThrowAnException() {
boolean expectedThrown = false;
try {
throw new RuntimeException();
} catch (RuntimeException e) {
expectedThrown = true;
}
assertTrue(expectedThrown);
}
}BankAccount.java
package com.objectmentor.jmock;
public interface BankAccount {
int getBalance();
void deduct(int i);
}Withdrawal.java
package com.objectmentor.jmock;
public class Withdrawal {
private BankAccount account;
private int amount;
public boolean executed;
public void setAmount(int amount) {
this.amount = amount;
}
public void setAccount(BankAccount account) {
this.account = account;
}
public void execute() {
if (account.getBalance() < amount) {
throw new InsufficientFunds();
}
account.deduct(amount);
executed = true;
}
public boolean isExecuted() {
return executed;
}
}InsufficientFunds.java
package com.objectmentor.jmock;
public class InsufficientFunds extends RuntimeException {
private static final long serialVersionUID = 1L;
}
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