PHPUnit Manual

Sometimes you want to assert that the execution of a method, for instance, generates an expected output (via echo or print, for example). The PHPUnit_Extensions_OutputTestCase class uses PHP's Output Buffering feature to provide the functionality that is necessary for this.

Example 8.1 shows how to subclass PHPUnit_Extensions_OutputTestCase and use its expectOutputString() method to set the expected output. If this expected output is not generated, the test will be counted as a failure.

<?php
require_once 'PHPUnit/Extensions/OutputTestCase.php';
 
class OutputTest extends PHPUnit_Extensions_OutputTestCase
{
    public function testExpectFooActualFoo()
    {
        $this->expectOutputString('foo');
        print 'foo';
    }
 
    public function testExpectBarActualBaz()
    {
        $this->expectOutputString('bar');
        print 'baz';
    }
}
?>

phpunit OutputTest
PHPUnit 3.5.14 by Sebastian Bergmann.

.F

Time: 0 seconds, Memory: 5.50Mb

There was 1 failure:

1) OutputTest::testExpectBarActualBaz
Failed asserting that two strings are equal.
--- Expected
+++ Actual
@@ @@
-bar
+baz


FAILURES!
Tests: 2, Assertions: 2, Failures: 1.

Table 8.1 shows the methods provided by PHPUnit_Extensions_OutputTestCase.

There are two other extensions to PHPUnit_Framework_TestCase, PHPUnit_Extensions_Database_TestCase and PHPUnit_Extensions_SeleniumTestCase, that are covered in Chapter 9 and Chapter 18, respectively.