test muladd mixing numbers and zerotangents

Author: oxinabox

test/rulesets/Base/base.jl

@@ -153,6 +153,17 @@
         test_rrule(muladd, 10randn(), randn(), randn())
     end
 
+    @testset "muladd ZeroTangent" begin
+        test_frule(muladd, 2.0, 3.0, ZeroTangent())
+        test_frule(muladd, 2.0, ZeroTangent(), 4.0)
+        test_frule(muladd, ZeroTangent(), 3.0,  4.0)
+
+        test_rrule(muladd, 2.0, 3.0, ZeroTangent())
+        test_rrule(muladd, 2.0, ZeroTangent(), 4.0)
+        test_rrule(muladd, ZeroTangent(), 3.0,  4.0)
+    end
+
+
     @testset "fma" begin
         test_frule(fma, 10randn(), randn(), randn())
         test_rrule(fma, 10randn(), randn(), randn())