Component bsls_asserttestexception [Package bsls]

Provide an exception type to support testing for failed assertions. More...

Namespaces
namespace	bsls

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Detailed Description

Outline

• Purpose
• Classes
• Description
  • Usage

Purpose:

Provide an exception type to support testing for failed assertions.

Classes:

bsls::AssertTestException

type describing the context of failed assertion

See also:

Component bsls_assert, Component bsls_asserttest

Description:

This component implements an exception class, bsls::AssertTestException, that provides a mechanism to convey context information from a failing assertion to a test handler. The context that is captured consists of the program source of the failing expression, the name of the file containing the assertion, the line number within that file where the asserted expression may be found, and the level of the assertion that has failed.

Note that this class is intended as an implementation detail of the bsls testing framework (see bsls_asserttest), though it may be used in other contexts.

Usage:

First we write a macro to act as an assert facility that will throw an exception of type bsls::AssertTestException if the asserted expression fails. The thrown exception will capture the source code, filename, and line number of the failing expression:

  #define TEST_ASSERT(EXPRESSION)                                          \$
      if (!(EXPRESSION)) {                                                 \$
          throw bsls::AssertTestException(#EXPRESSION, __FILE__, __LINE__, \$
                                          "LEVEL");                        \$
  }

Next we use the macro inside a try-block, so that we can catch the exception thrown if the tested expression fails:

  try {
      void *p = NULL;
      TEST_ASSERT(0 != p);
  }

If the assertion fails, catch the exception and confirm that it correctly recorded the context of where the assertion failed:

  catch (const bsls::AssertTestException& exception) {
      assert(0 == strcmp("0 != p", exception.expression()));
      assert(0 == strcmp(__FILE__, exception.filename()));
      assert(9 == __LINE__ - exception.lineNumber());
      assert(0 == strcmp("LEVEL", exception.level());
  }