What is LTP ?

Linux already has a successful testing model. How will this project benefit Linux further?

There is no such thing as a perfect test base. It's only useful if it keeps up with new and changing functionality, and if it actually gets used.

What is in the LTP, so far?

How do I build this?

How do I run this? How does it work?

A problem that needs to be addressed is how to store different command lines and determining when to run them. A couple examples are, should a bigmem test be run on a 128Mb system? Should a file system test that requires 2Gb of scratch space be run on a system without such a test space? These two example highlight a couple of issues that need to be addressed in regard to the runtime framework for tests.

How do I analyze the results?

The simplest form is the exit status of the program. If a test hits a scenario where it finds unexpected or improper results, calling exit() with a non-zero exit status would flag the caller that the test failed for some reason. Conversely, if the test completes with the functionality performing as expected, a zero exit would flag the caller that the test passed. Summarizing: exit(0)==PASS, exit(!0)==FAIL. Additionally, the test program could report some sort of information on standard output indicating why the test passed or failed.

Another form of results reporting used within SGI is a hybrid of the exit() style reporting. It still uses the exit status for reporting, but incorporates a standard format for output from standard output of the test program. This accomplishes two things: allows the reporting of the functional testing results to be more understandable for both humans and a computer analysis tool and allows more than one test case result to be reported from within one test program. This is in contrast to a pure exit status analysis where a test program may contain N test cases and one test case fails, the test program returns a non-zero value. It appears that the whole test fails. Compare this to a scenario where a test reports for each test case a PASS or FAIL token on standard output.

For quick clarity, take this example:

$ ./dup02
dup02       1  PASS  :  dup(-1) Failed, errno=9 : Bad file descriptor
dup02       2  PASS  :  dup(1500) Failed, errno=9 : Bad file descriptor

Additionally, the exit status should be zero, indicating all the test cases passed. Accessing the exit status of the test program can be reported immediately after running the test program by printing the $? variable.

$ echo $?
0

Finally, we can analyze the results of the dup02 test program on two fronts. We can see from the two PASS lines, that both test cases in the dup02 program passed. We can also see from the exit status that the dup02 program as a whole passed.

What if a test program reports a failure?

Determining what test case is reporting a failure is sometimes a challenge. In some cases, in a multiple test case test program, previous test cases can cause failure in subsequent test cases. If a test is well written, the output on standard output can be useful.

Once the test case the "failure" is occuring under is osolated, determining whether the "failure" is really a failure needs to be determined. If a test is poorly written and certain environmental conditions are not handled properly, a false failure may occur.

Comparing the failure on the system under test against a baseline system is important. If the test fails on a system but it is unknown if it ever passed on any other system, its not possible to determine if the problem is a new failure. Comparing how the functionality under test performs on the baseline against how it acts on the test system is the most important method for determining how the "failure" occured.

What is a test?