How to use output buffering inside PHPUnit test?

Question

I'm using PHPUnit to test a function which downloads a file. I want to test that the correct file is downloaded and so my idea was to check the output of the function. I'm trying to use output buffering:

ob_start();
$viewer->downloadById($fileId);
$output = ob_get_flush();
$this->assertEquals($expectedFileContents,$output);

The test passes/fails when it should, which is good. My issue is that the contents of the output buffer is also printed to the console. How do I hide this?

Answer 1

Use ob_get_clean() instead of ob_get_flush(). The former will remove the buffer without printing it and return its contents. The latter will do the same and print the contents of the buffer.