Test that output does not contain text

Question

I know how to test php output with PHPUnit library, using expectOutputString() or expectOutputString(). Now I need to be sure that output doesn't contain given string. I can do this using output buffering and searching for string inside but probably better way is to use expectOutputString() with proper expression.

How should this expression be built?

Answer 1

You want to use a regex, and to do a negative match you have to use the lookahead assertion syntax. E.g. to test that the output does not contain "hello":

class OutputRegexTest extends PHPUnit_Framework_TestCase
{
    private $regex='/^((?!Hello).)*$/s';

    public function testExpectNoHelloAtFrontFails()
    {
        $this->expectOutputRegex($this->regex);
        echo "Hello World!\nAnother sentence\nAnd more!";
    }

    public function testExpectNoHelloInMiddleFails()
    {
        $this->expectOutputRegex($this->regex);
        echo "This is Hello World!\nAnother sentence\nAnd more!";
    }

    public function testExpectNoHelloAtEndFails()
    {
        $this->expectOutputRegex($this->regex);
        echo "A final Hello";
    }

    public function testExpectNoHello()
    {
        $this->expectOutputRegex($this->regex);
        echo "What a strange world!\nAnother sentence\nAnd more!";
    }
}

Gives this output:

$ phpunit testOutputRegex.php 
PHPUnit 3.6.12 by Sebastian Bergmann.

FFF.

Time: 0 seconds, Memory: 4.25Mb

There were 3 failures:

1) OutputRegexTest::testExpectNoHelloAtFrontFails
Failed asserting that 'Hello World!
Another sentence
And more!' matches PCRE pattern "/^((?!Hello).)*$/s".


2) OutputRegexTest::testExpectNoHelloInMiddleFails
Failed asserting that 'This is Hello World!
Another sentence
And more!' matches PCRE pattern "/^((?!Hello).)*$/s".


3) OutputRegexTest::testExpectNoHelloAtEndFails
Failed asserting that 'A final Hello' matches PCRE pattern "/^((?!Hello).)*$/s".


FAILURES!
Tests: 4, Assertions: 4, Failures: 3.