phpunit: reusing dataprovider - iterator

Question

I want to run multiple test cases against the content of a whole set of files. I could use a data provider to load my files and use the same provider for all the tests like this:
class mytest extends PHPUnit_Framework_TestCase {
public function contentProvider() {
return glob(__DIR__ . '/files/*');
}
/**
* #dataProvider contentProvider
*/
public function test1($file) {
$content = file_get_contents($file);
// assert something here
}
...
/**
* #dataProvider contentProvider
*/
public function test10($file) {
$content = file_get_contents($file);
// assert something here
}
}
Obviously that means if I have 10 test cases, each file is loaded 10 times.
I could adjust the data provider to load all files and return one big structure with all the contents. But since the provider is called separately for each test it would still mean each file is loaded 10 times and in addition it would load all files into memory at the same time.
I could of course condense the 10 tests into one test with 10 assertions, but then it would abort right after the first assertion fails and I really want a report of all things that are wrong with the file.
I know that data providers can also return an iterator. But phpunit seems to rerun the iterator separately for each test, still resulting in loading each file 10 times.
Is there a clever way to make phpunit run an iterator only once and pass the result to each test, before continuing?

Answer 1

Test dependencies
If some tests are dependents, you should use the #depends annotation to declare Test dependencies. The data returned by the dependency is used by the test declaring this dependency.
But, if a test declared as dependency failed, the dependent test is not executed.
Statically stored data
To share data between tests, it's common to setup fixtures statically.
You can use the same method with data providers:
<?php
use PHPUnit\Framework\TestCase;
class MyTest extends TestCase
{
private static $filesContent = NULL;
public function filesContentProvider()
{
if (self::$filesContent === NULL) {
$paths = glob(__DIR__ . '/files/*');
self::$filesContent = array_map(function($path) {
return [file_get_contents($path)];
}, $paths);
}
}
/**
* #dataProvider filesContentProvider
*/
public function test1($content)
{
$this->assertNotEmpty($content, 'File must not be empty.');
}
/**
* #dataProvider filesContentProvider
*/
public function test2($content)
{
$this->assertStringStartsWith('<?php', $content,
'File must start with the PHP start tag.');
}
}
As you can see, it's not supported out of the box. As the test class instance is destroyed after each test method execution, you have to store the initialized data in a class variable.