Consider the following scenario (this is not production code):
class MyClass {
public function myMethod() {
// create a directory
$path = sys_get_temp_dir() . '/' . md5(rand());
if(!mkdir($path)) {
throw new Exception("mkdir() failed.");
}
// create a file in that folder
$myFile = fopen("$path/myFile.txt", "w");
if(!$myFile) {
throw new Exception("Cannot open file handle.");
}
}
}
Right, so what's the problem? Code coverage reports that this line is not covered:
throw new Exception("Cannot open file handle.");
Which is correct, but since I'm creating the folder above logically it would seem impossible for the fopen() to fail (except maybe in extreme circumstances, like disk at 100 %).
I could ignore the code from code coverage but thats kind of cheating. Is there any way I can mock the file system so that it can recognise myFile.txt and mock the file system unable to create the file?
vfsStream is a stream wrapper for a virtual filesystem that is useful in unit tests to mock the real filesystem. You can install it from composer.
More Info at:
Yes!
You should inject the full path somehow, and don't call sys_get_temp_dir() right in that method.
Any non-existant path should trigger a problem. You don't need VFS for that.
BUT you will get a E_NOTICE (or warning perhaps?) before the exception is triggered. So you should probably first check is_writable, and throw the exception if it returns false.
You could also break the function into 2 methods, one to create the path, and the other to use it. Then, individual tests could be done to ensure the path is created. A second set of tests could check and capture the exception when you try to use a bad path.