TESTPACK is a FORTRAN77 library which demonstrates the testing of a routine for multidimensional integration.
In this case, the code being tested is a subroutine known as ADAPT, written by Genz. The code is tested on six test integrand functions, also defined by Genz. The test is done with a variety of spatial dimensions, parameter values, and difficulty factors.
TESTPACK is available in a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version.
INTEGRAL_TEST, a FORTRAN90 program which tests the suitability of a set of N points for use in an equal-weight quadrature rule over the M-dimensional unit hypercube.
INTLIB, a FORTRAN90 library which estimate the integral of a function over a one-dimensional interval.
KRONROD, a FORTRAN77 library which can compute a Gauss and Gauss-Kronrod pair of quadrature rules of arbitrary order, by Robert Piessens, Maria Branders.
NINTLIB, a FORTRAN77 library which estimates the integral of a function over a one-dimensional interval.
QUADRULE, a FORTRAN90 library which defines a variety of (mostly 1-dimensional) quadrature rules.
SMOLPACK, a C library which uses the Genz test functions to demonstrate quadrature in multiple dimensions using a sparse grid.
SPINTERP, a MATLAB library which uses the Genz test functions to demonstrate multilinear interpolation on a sparse grid.
STROUD, a FORTRAN90 library which defines a variety of quadrature rules over various "interesting" geometric shapes.
TEST_NINT, a FORTRAN90 library which can be used to test N-dimensional quadrature routines.
You can go up one level to the FORTRAN77 source codes.