A Classic-Style Assertion: assertTrue
This lesson will explain the use and importance of using assertTrue in writing Unit tests.
We'll cover the following
The most basic Classic-Style Assertion is assertTrue
:
org.junit.Assert.assertTrue(someBooleanExpression);
Since assertions are so pervasive in JUnit tests, most programmers use a static
import to reduce the clutter:
import static org.junit.Assert.*;
An assertTrue
ensures that a value is true
, otherwise it gives a false
. A couple of examples:
@Test
public void hasPositiveBalance() {
account.deposit(50);
assertTrue(account.hasPositiveBalance());
}
If the parameter in assertTrue
evaluates as true
, then the above test will pass.
@Test
public void depositIncreasesBalance() {
int initialBalance = account.getBalance();
account.deposit(100);
assertTrue(account.getBalance() > initialBalance);
}
The above test (depositIncreasesBalance
) is testing whether the balance in an account is greater than the initial balance after a deposit of 100
is added. The assertTrue
assertion makes sure that the condition is true
.
@Before Account instance
The previous examples depend on the existence of an initialized Account
instance. We can create an Account
in an @Before
method and store a reference as a field in the test class:
private Account account;
@Before
public void createAccount() {
account = new Account("an account name");
}
We have been provided with an Account
class in this example. Run the tests below to check if they pass.
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