fail if errror message

src/funcs.f90

@@ -446,7 +446,7 @@ elemental real(wp) FUNCTION RIEMANNZETA (S,EPS)
 
 NSTERM = S*(S+1)*(S+2)* &
   (S+3)*(S+4)/30240
-N = int((NSTERM*(2**S)/EPS)**(1._wp/(S+5)))
+N = int((NSTERM*(2**S)/EPS)**(1 / (S+5)))
 IF ( N < 10 )  THEN
    N = 10
 END IF
@@ -461,7 +461,7 @@ elemental real(wp) FUNCTION RIEMANNZETA (S,EPS)
 
 !     Add Euler-Maclaurin correction terms
 SUM = SUM+(FN**NEGS)*(0.5D00+FN/(S-1) &
-  +S*(1._wp-(S+ 1._wp)*(S+2)/ &
+  +S*(1 - (S + 1)*(S+2)/ &
   (60*FN*FN)) &
   /(12*FN))+NSTERM/(FN**(S+5))
 riemannZETA = SUM

tests/test_functions.py

@@ -22,8 +22,9 @@ def frun(name: str, args) -> float:
     if not isinstance(args, (list, tuple)):
         args = [args]
     input = "\n".join(map(str, args)) + "\n" + name
-    raw = subprocess.check_output([EXE], input=input, text=True, timeout=5)
-    return float(raw.strip().split("\n")[-1])
+    raw = subprocess.run([EXE], capture_output=True, input=input, text=True, timeout=5)
+    assert not raw.stderr, raw.stderr
+    return float(raw.stdout.strip().split("\n")[-1])
 
 
 def test_bessel0():
@@ -56,5 +57,10 @@ def test_bessel_general():
             assert frun(k, a) == approx(f(*a))
 
 
+def test_riemann_zeta():
+
+    assert frun("rzeta", (2)) == approx(sp.zeta(2))
+
+
 if __name__ == "__main__":
     pytest.main([__file__])