TST: add test for gh-92

Author: JaRoSchm

tests/xsf_tests/test_amos.cpp

@@ -49,3 +49,35 @@ TEST_CASE("amos besj", "[amos][xsf_tests]") {
         REQUIRE(rel_error <= 1e-14);
     }
 }
+
+TEST_CASE("amos besh vectorized", "[amos][xsf_tests]") {
+    // tests the functionality of amos to return multiple consecutive orders for besh
+    // by comparing to the versions returning only a single order
+    using std::complex;
+
+    using test_case = std::tuple<complex<double>, double, int, int, int, double>;
+    auto [z, fnu, kode, m, n, rtol] = GENERATE(
+        test_case{complex{14.0, -3.0}, 1.0, 1, 1, 260, 4e-13} // gh-92
+    );
+
+    std::vector<complex<double>> cy(n);
+    int ierr = 0;
+    int nz;
+
+    nz = xsf::amos::besh(z, fnu, kode, m, n, cy.data(), &ierr);
+
+    REQUIRE(ierr == 0);
+    REQUIRE(nz == 0);
+
+    complex<double> ref;
+
+    for (int i = 0; i < n; ++i) {
+        nz = xsf::amos::besh(z, fnu + i, kode, m, 1, &ref, &ierr);
+        REQUIRE(ierr == 0);
+        REQUIRE(nz == 0);
+
+        const auto rel_error = xsf::extended_relative_error(cy[i], ref);
+        CAPTURE(i, cy[i], ref, rel_error);
+        REQUIRE(rel_error <= rtol);
+    }
+}