From 022dbe979bd73fbab5b6db57ad918f78eae8acf5 Mon Sep 17 00:00:00 2001
From: jzmaddock <john@johnmaddock.co.uk>
Date: Thu, 8 May 2025 18:39:51 +0100
Subject: [PATCH] Coverage: Improve sinc_pi complex tests.

---
 test/sinc_test.hpp | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/test/sinc_test.hpp b/test/sinc_test.hpp
index 4d1caa0c8..86e840e72 100644
--- a/test/sinc_test.hpp
+++ b/test/sinc_test.hpp
@@ -13,9 +13,11 @@
 
 
 #include <boost/math/special_functions/sinc.hpp>
+#include <boost/multiprecision/cpp_complex.hpp>
 
 #define BOOST_TEST_MAIN
 #include <boost/test/unit_test.hpp>
+#include <boost/test/tools/floating_point_comparison.hpp>
 
 
 BOOST_TEST_CASE_TEMPLATE_FUNCTION(sinc_pi_test, T)
@@ -53,6 +55,24 @@ BOOST_TEST_CASE_TEMPLATE_FUNCTION(sinc_pi_complex_test, T)
         (abs(sinc_pi<T>(::std::complex<T>(0, 1))-
              ::std::complex<T>(sinh(static_cast<T>(1)))))
         (numeric_limits<T>::epsilon()));
+
+    //
+    // A very poor test with rather large tolerance for failure.
+    // But it does get out coverage up!
+    //
+    T tolerance = std::numeric_limits<T>::epsilon() * 20000;
+
+    std::complex<T> val(1, 2);
+    for (unsigned i = 0; i < 5; ++i)
+    {
+       using mp_t = boost::multiprecision::cpp_complex_50;
+       val /= 3;
+       std::complex<T> r1, r2;
+       r1 = sinc_pi<T>(val);
+       r2 = static_cast<std::complex<T>>(sin(mp_t(val)) / mp_t(val));
+       BOOST_CHECK_CLOSE_FRACTION(arg(r1), arg(r2), tolerance);
+       BOOST_CHECK_CLOSE_FRACTION(abs(r1), abs(r2), tolerance);
+    }
 }