NAME

     zt_claim — structure capturing unevaluated assertion

SYNOPSIS

     #include <zt.h>

     typedef struct zt_claim { ... } zt_claim;

     Type                              Member            Description
     struct zt_verifier *(*)(void)     make_verifier     Verifier factory
     zt_value[3]                       args              verifier arguments
     zt_location                       location          origin of the claim

DESCRIPTION

     zt_claim binds a verifier factory function with concrete arguments. This allows the entire
     claim to be passed around and evaluated on demand. In case of failure the location where the
     claim was made can be referenced for construction of error messages.

IMPLEMENTATION NOTES

     The verification system is comprised of the following chain of cooperating elements. For
     example a trivial integer relationship assertion behaves as follows.  ZT_CMP_INT(), or
     another similar macro, invokes zt_cmp_int(), providing source code location as zt_location,
     and packaging specific types into common variant type zt_value.  The result is a zt_claim
     which is then passed to zt_assert() or zt_check() for evaluation.

     The roles of all the essential types and functions is summarized below.

     ·   zt_value captures values expressed in a test case

     ·   zt_claim transports up to three values and an opaque verifier

     ·   zt_check() and zt_assert() validate the claim by instantiating zt_verifier.

     ·   zt_verifier (private) wraps a verification function, including the arity and expected
         kind of each argument.

     ·   zt_arg_info (private) pairs expected argument kind with a customized error message used
         on kind mismatch.

     ·   zt_verify_claim() (private) ensures verifier function arity and argument kind matches
         what is encoded in the claim and invokes the verifier function.

     ·   The specific verifier function inspects the argument and performs the actual
         verification of the desired property that the test is measuring.

     ·   zt_test (private) keeps track of test outcome, provides a stream for writing error
         messages and assists in performing non-local exit.

SEE ALSO

     zt_assert(3), zt_check(3)

HISTORY

     zt_claim first appeared in libzt 0.1

BUGS

     Part of the API is private which prevents third party verification functions from being
     written. This is done on purpose to to allow for some more experimentation before
     stabilizing the interface.

AUTHORS

     Zygmunt Krynicki <me@zygoon.pl>