Revert "also comment out trinary tests"

This reverts commit 148b29c.

test/runtests.jl

@@ -47,7 +47,6 @@ for (M, f, arity) in DiffRules.diffrules()
             end
         end
     elseif arity == 3
-        #=
         @test DiffRules.hasdiffrule(M, f, 3)
         derivs = DiffRules.diffrule(M, f, :foo, :bar, :goo)
         @eval begin
@@ -63,7 +62,6 @@ for (M, f, arity) in DiffRules.diffrules()
                 @test isapprox(dz, finitediff(z -> $M.$f(foo, bar, z), goo), rtol=0.05)
             end
         end
-        =#
     end
 end
 
@@ -82,7 +80,6 @@ for xtype in [:Float64, :BigFloat, :Int64]
 end
 
 # Test ifelse separately as first argument is boolean
-#=
 @test DiffRules.hasdiffrule(:Base, :ifelse, 3)
 derivs = DiffRules.diffrule(:Base, :ifelse, :foo, :bar, :goo)
 for cond in [true, false]
@@ -94,4 +91,4 @@ for cond in [true, false]
         @test isapprox(dz, finitediff(z -> ifelse(foo, bar, z), goo), rtol=0.05)
     end
 end
-=#
+