automake-1.16: Generalities about Testing
15.1 Generalities about Testing
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The purpose of testing is to determine whether a program or system
behaves as expected (e.g., known inputs produce the expected outputs,
error conditions are correctly handled or reported, and older bugs do
not resurface).
The minimal unit of testing is usually called _test case_, or simply
_test_. How a test case is defined or delimited, and even what exactly
_constitutes_ a test case, depends heavily on the testing paradigm
and/or framework in use, so we won’t attempt any more precise
definition. The set of the test cases for a given program or system
constitutes its _testsuite_.
A _test harness_ (also _testsuite harness_) is a program or software
component that executes all (or part of) the defined test cases,
analyzes their outcomes, and reports or registers these outcomes
appropriately. Again, the details of how this is accomplished (and how
the developer and user can influence it or interface with it) varies
wildly, and we’ll attempt no precise definition.
A test is said to _pass_ when it can determine that the condition or
behaviour it means to verify holds, and is said to _fail_ when it can
determine that such condition of behaviour does _not_ hold.
Sometimes, tests can rely on non-portable tools or prerequisites, or
simply make no sense on a given system (for example, a test checking a
Windows-specific feature makes no sense on a GNU/Linux system). In this
case, accordingly to the definition above, the tests can neither be
considered passed nor failed; instead, they are _skipped_, that is, they
are not run, or their result is in any case ignored for what concerns
the count of failures and successes. Skips are usually explicitly
reported though, so that the user will be aware that not all of the
testsuite has been run.
It’s not uncommon, especially during early development stages, that
some tests fail for known reasons, and that the developer doesn’t want
to tackle these failures immediately (this is especially true when the
failing tests deal with corner cases). In this situation, the better
policy is to declare that each of those failures is an _expected
failure_ (or _xfail_). In case a test that is expected to fail ends up
passing instead, many testing environments will flag the result as a
special kind of failure called _unexpected pass_ (or _xpass_).
Many testing environments and frameworks distinguish between test
failures and hard errors. As we’ve seen, a test failure happens when
some invariant or expected behaviour of the software under test is not
met. A _hard error_ happens when e.g., the set-up of a test case
scenario fails, or when some other unexpected or highly undesirable
condition is encountered (for example, the program under test
experiences a segmentation fault).
Info Catalog
automake-1.16: Tests
automake-1.16: Simple Tests