Testing PHP code with SimpleTest

This is the first article of a series of articles where I am looking at various PHP tools for test automation. How they integrate (or not) with other test automation systems. In this article I provide an introduction to SimpleTest


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Welcome back

I have started to write the slides for the PHP testing chapter of my test automation training. Let me share the first few pages with you.

Almost manually testing

In the first examples we recreate a path similar to what we take in the Perl introduction in my classes. It might be slow a bit for people who are familiar with testing already but will give the basic idea of what we try to achieve.

Let's assume we have a simple PHP library with a bunch of functions. It is located in our "includes" directory in the mylib.php file. It is used by a "web application" called basic_calc.php that provides a - surprise - calculator for the web visitor.

For now, we won't test the web application itself just the functions it uses.

In order to test the library we create a separate PHP script that will require the relevant library and call the add() function supplying various arguments and displaying the results.

Then we eyeball those results to see if they are what they should be.

Save this as SOMEDIR/intro/t01.php


  <?php

  require_once(dirname(__FILE__) . '/../includes/mylib.php');

  print add(1,1) . '<br>';
  print add(2,2) . '<br>';
  print add(1,1,1) . '<br>';

  ?>

When looking at that page with your browser, the output will look like this:


  2
  4
  2

Not much of an output but if we are careful we'll see that the third line is incorrect. The problem is that it is a lot of effort to check if the results are correct.

BTW dirname(__FILE__) just gives the path to the directory of currently executing file and we know the library we are testing is relative to it.

Setup

Just so you can also follow the examples, save the following content in SOMEDIR/includes/mylib.php That's the "library" we are testing.


  <?php

  function add($a, $b) {
    return $a+$b;
  }

  ?>

From looking at this code it is obvious what is the problem in the add() function but we are now only interested in seeing how we can test it not fixing it.

Print expected values as well

So the problem is that the test runner has to compute the expected results every time she runs the test script. A slight improvement will be to show the expected results next to the actual values.

Save this as SOMEDIR/intro/t02.php


  <?php
  
  require_once(dirname(__FILE__) . '/../includes/mylib.php');
  
  print add(1,1)   . ' == 2<br>';
  print add(2,2)   . ' == 4<br>';
  print add(1,1,1) . ' == 3<br>';
  
  ?>

Output in the browser:


  2 == 2
  4 == 4
  2 == 3

This is still hard to follow when there are lots of cases or even a few cases with large output but it seems to be a step in the good direction.

Compare actual with expected values and print only pass/fail

Instead of manually comparing the actual results with the expected values let the computer do the hard work and let it only print if there was a success or a failure. We introduce some new code that will print "pass" for every case when the result was the expected value and "fail" when they were different.


  <?php

  require_once(dirname(__FILE__) . '/../includes/mylib.php');
  
  print (add(1,1)   == 2 ? 'pass' : 'fail') . '<br>';
  print (add(2,2)   == 4 ? 'pass' : 'fail') . '<br>';
  print (add(1,1,1) == 3 ? 'pass' : 'fail') . '<br>';

  ?>

The output in the web browser is


  pass
  pass
  fail

This is certainly an improvement but before we further improve our display let's turn our attention to our own testing code.

Refactor to get assertTrue

As we are also programmers we will soon recognize that there is code duplication in our test script and will factor out the whole printing of pass/fail part to a function that we call assertTrue(). It should receive a true or false value and it will print "pass" or "fail" accordingly.


  <?php

  require_once(dirname(__FILE__) . '/../includes/mylib.php');

  assertTrue(add(1,1)   == 2);
  assertTrue(add(2,2)   == 4);
  assertTrue(add(1,1,1) == 3);

  function assertTrue($condition) {
    print ($condition ? 'pass' : 'fail') . '<br>';
  }

  ?>

The output


  pass
  pass
  fail

As in every refactoring the functionality and the output should remain the same, just the implementation improves. (Hopefully)

Introduction to the PHP SimpleTest framework

That's all very nice but someone has already implemented this with a lot of other nice features. We are going to look at the SimpleTest framework of PHP.

I am looking at the currently latest 1.0.1 version that already includes autorun.php.

Ubuntu packages the PHP Simpletest package but


  sudo aptitude install php-simpletest
  

only gets you version 1.0 which is relatively old.

So the best course of action is to download the simpletest_1.0.1.tar.gz file from the Simpletest web site and unzip it in a place where your web server can reach it.

assertTrue in SimpleTest

We unzipped the simpletest tar.gz file to a directory in the course directory structure some 3 levels above the actual examples.

The first thing we'll have to do in our code is to load the autorun.php file from the simpletest directory. That file, as its name also reveals will run our tests automatically when we hit the page.

The next thing is to pay the overhead of the test writing. Luckily we'll only need to pay it once for every group of tests. This is Object Oriented code but even if you are not yet familiar with OO you don't have to worry. The tests themselves are simple functions calls.

We need to create a class that extends UnitTestCase class provided by SimpleTest. The name ( in our example TestOfAdd ) of the class does not really matter but as usual, it is better if it is descriptive of what the tests are going to, err ... test.

Withing the class we need to implement a function ( testAdd in our example ) that will include the test cases. In the case of the function the name has to start with "test" but beyond that it does not matter what exactly it is. It should be descriptive.

Within the function we can call the assertTrue method on the $this object. For those not familiar with OO, $this is provided automatically and the -> notion is just a fancy way of calling the assertTrue() function.


  <?php

  require_once(dirname(__FILE__) . '/../../../tools/simpletest/autorun.php');

  require_once(dirname(__FILE__) . '/../includes/mylib.php');

  class TestOfAdd extends UnitTestCase {
    function testAdd() {
      $this->assertTrue(add(1,1) == 2);
      $this->assertTrue(add(2,2) == 4);
      $this->assertTrue(add(1,1,1) == 3);
    }
  }

  ?>

Output:


  st01.php
  Fail: TestOfAdd -> testAdd -> 
  at [.../testing/examples/php/simpletest/st01.php line 11]
  1/1 test cases complete: 2 passes, 1 fails and 0 exceptions.

With the last row being RED

So TestSimple collapses all our individual results and conveniently only shows the aggregated result and the individual tests that actually failed.

Unfortunately this report only gives us the line number of where the assertion that failed. No other details about the failure.

SimpleTest Success

Just in order so we see it I include an example where I removed the failing test and in the following example all of the assertions are successful. Actually you won't see much as this newsletter is plain text and I cannot include the nice colors.


  st02.php
  1/1 test cases complete: 2 passes, 0 fails and 0 exceptions.

With the last row being GREEN

assertEqual showing the actual values

SimpleTest and its UnitTestCase class provides further methods for assertions with better error reporting. In the end they all report assertions but these others have better capabilities in providing details on the failures.

In our case we could use assertEqual method instead of the assertTrue method. This one should receive two values. One of them should be the expected value the other one the actual result. The library does not make a recommendation which is which, it treats the two values in the same way and only checks if they are equal or not.


  <?php

  require_once(dirname(__FILE__) . '/../../../tools/simpletest/autorun.php');

  require_once(dirname(__FILE__) . '/../includes/mylib.php');

  class TestOfAdd extends UnitTestCase {
    function testAdd() {
      $this->assertEqual(add(1,1), 2);
      $this->assertEqual(add(2,2), 4);
      $this->assertEqual(add(1,1,1), 3);
    }
  }

  ?>

Output:


  st03.php
  Fail: TestOfAdd -> testAdd -> Equal expectation fails because [Integer: 2] 
  differs from [Integer: 3] by 1 at 
  [.../testing/examples/php/simpletest/st03.php line 11]
  1/1 test cases complete: 2 passes, 1 fails and 0 exceptions.

With the last row being RED

As you can see there is now a better explanation of what failed.

SimpleTest showing description of error

The assert* methods of SimpleTest allow an optional additional parameter which is the description of the current assertion. In case of failure it will be shown instead of the details of the error


  <?php

  require_once(dirname(__FILE__) . '/../../../tools/simpletest/autorun.php');

  require_once(dirname(__FILE__) . '/../includes/mylib.php');

  class TestOfAdd extends UnitTestCase {
    function testAdd() {
      $this->assertEqual(add(1,1), 2, "1+1");
      $this->assertEqual(add(2,2), 4, "2+2");
      $this->assertEqual(add(1,1,1), 3, "three params 1+1+1");
    }
  }

  ?>


Output:


  st04.php
  Fail: TestOfAdd -> testAdd -> three params 1+1+1 at 
  [.../testing/examples/php/simpletest/st04.php line 11]
  1/1 test cases complete: 2 passes, 1 fails and 0 exceptions.

With the last row being RED

Further reading about PHP SimpleTest

The PHP SimpleTest framework provides lots of additional tools for testing your application. The documentation for the UnitTestCase class with the list of various assert methods can be found here.

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This entry was first sent out as part of the Test Automation Tips. Visit here to subscribe.

Published on 2009-03-11 by Gabor Szabo
Code::Maven
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