bsls_fuzztestpreconditionexception

Detailed Description

Provide an exception type for handling failed preconditions.

Outline

• Purpose
• Classes
• Description
  • Usage

Purpose

Provide an exception type for handling failed preconditions.

Classes

• bsls::FuzzTestPreconditionException: type describing a failed precondition

See also

bsls_fuzztest

Description

This component implements an exception class, bsls::FuzzTestPreconditionException, that provides a mechanism to convey context information from a failing precondition 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/review, the line number within that file where the asserted/reviewed expression may be found, and the level of the assertion/review that has failed.

Usage

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

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

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_PRECONDITION(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::FuzzTestPreconditionException& 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()));
        assert(false == exception.isReview());
    }