Add missing file!

Author: jzmaddock

test/git_issue_1247.cpp

@@ -0,0 +1,21 @@
+//  (C) Copyright John Maddock 2025.
+//  Use, modification and distribution are subject to the
+//  Boost Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// See also: https://godbolt.org/z/nhMsKb8Yr
+
+#include <boost/math/special_functions/beta.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+int main()
+{
+   float a = 1e-20;
+   float b = 1e-21;
+   float z = 0.5;
+   float p = boost::math::ibeta(a, b, z, boost::math::policies::make_policy(boost::math::policies::promote_float<false>()));
+
+   BOOST_TEST(p != 0);
+
+   return boost::report_errors();
+}