Java/ JUnit - AssertTrue vs AssertFalse

assertTrue will fail if the second parameter evaluates to false (in other words, it ensures that the value is true). assertFalse does the opposite.

assertTrue("This will succeed.", true);assertTrue("This will fail!", false);assertFalse("This will succeed.", false);assertFalse("This will fail!", true);

As with many other things, the best way to become familiar with these methods is to just experiment :-).

Your understanding is incorrect, in cases like these always consult the JavaDoc.

assertFalse

public static void assertFalse(java.lang.String message,                               boolean condition)

Asserts that a condition is false. If it isn't it throws an AssertionError with the given message.

Parameters:

• message - the identifying message for the AssertionError (null okay)
• condition - condition to be checked

The point is semantics. In assertTrue, you are asserting that the expression is true. If it is not, then it will display the message and the assertion will fail. In assertFalse, you are asserting that an expression evaluates to false. If it is not, then the message is displayed and the assertion fails.

assertTrue (message, value == false) == assertFalse (message, value);

These are functionally the same, but if you are expecting a value to be false then use assertFalse. If you are expecting a value to be true, then use assertTrue.