Add test for complex equations

Author: contradict

test/complex.jl

@@ -0,0 +1,16 @@
+using ModelingToolkit
+using ModelingToolkit: t_nounits as t
+using Test
+
+@mtkmodel ComplexModel begin
+    @variables begin
+        x(t)
+        y(t)
+        z(t)::Complex
+    end
+    @equations begin
+        z ~ x + im*y
+    end
+end
+@named mixed = ComplexModel()
+@test length(equations(mixed)) == 2

test/runtests.jl

@@ -73,6 +73,7 @@ end
             @safetestset "Initial Values Test" include("initial_values.jl")
             @safetestset "Discrete System" include("discrete_system.jl")
             @safetestset "Equation Type Accessors Test" include("equation_type_accessors.jl")
+            @safetestset "Equations with complex values" include("complex.jl")
         end
     end