Add test for complex number printing

Author: MilesCranmer

test/test_print.jl

@@ -38,3 +38,20 @@ for binop in [safe_pow, ^]
     minitree = Node(5, Node("x1"), Node("x2"))
     @test string_tree(minitree, opts) == "(x1 ^ x2)"
 end
+
+@testset "Test printing of complex numbers" begin
+    @eval my_custom_op(x, y) = x + y
+    operators = OperatorEnum(;
+        default_params...,
+        binary_operators=(+, *, /, -, my_custom_op),
+        unary_operators=(cos, sin),
+    )
+    @extend_operators operators
+    x1, x2, x3 = [Node(; feature=i) for i in 1:3]
+    tree = sin(x1 * 1.0)
+    @test string_tree(tree, operators) == "sin(x1 * 1.0)"
+    tree = sin(x1 * (1.0 + 2.0im))
+    @test string_tree(tree, operators) == "sin(x1 * (1.0 + 2.0im))"
+    tree = my_custom_op(x1, 1.0 + 2.0im)
+    @test string_tree(tree, operators) == "my_custom_op(x1, 1.0 + 2.0im)"
+end