How to find the reason for a risky test in PHPUnit

Question

From time to time I get a risky test in PHPUnit. Usually I can find the reason for a risky test. But the task can be time consuming, because I do not see any messages from PHPUnit, why a test is marked as risky. I only get something like this:

PHPUnit 4.4.5 by Sebastian Bergmann.  Configuration read from phpunit.xml.dist  R...................R.R...  Time: 11,91 seconds, Memory: 42,50Mb  OK, but incomplete, skipped, or risky tests! Tests: 26, Assertions: 32, Risky: 3.         

Is there any option to tell PHPUnit to show messages or better something like stack traces to the code causing the risky flag? A complete list of causes for a risky test might prove helpful, too.

Answer 1

This question deserves an answer, taken from comments above.

phpunit -v 

This gives a short description of the reason for the risky test

 -v|--verbose              Output more verbose information. 

Answer 2

As of PHPUnit 5.3, the complete list of risky reasons:

• A test makes no assertions, when being strict about tests that do nothing. (Source.)
• A test marked with @todo, when being strict about TODO annotations. (Source.)
• Using a function that operates on a resource, when running a small test and being strict about resource usage. (Source: thrown here based on this condition.)
• Code does not close exactly the output buffers it opened. (Source.)
• Code executes methods not explicitly listed in @covers for the test. (Source. A blog post on this scenario.)
• Code manually throws a PHPUnit_Framework_RiskyTestError.
• Code manually throws a PHPUnit_Framework_UnintentionallyCoveredCodeError.