Include test of many operators to stress test @nif

Author: MilesCranmer

test/test_evaluation.jl

@@ -158,3 +158,20 @@ if VERSION >= v"1.7"
         @test stack[1].exception isa MethodError
     end
 end
+
+@testset "Test many operators" begin
+    # Since we use `@nif` in evaluating expressions,
+    # we can see if there are any issues with LARGE numbers of operators.
+    binary_operators = [@eval function (x, y)
+        return x + y
+    end for i in 1:100]
+    unary_operators = [@eval function (x)
+        return x^2
+    end for i in 1:100]
+    operators = OperatorEnum(; binary_operators, unary_operators)
+    tree = Node(1, Node(50, Node(; val=3.0), Node(; feature=2)))
+    # = (3.0 + x2)^2
+    X = randn(Float64, 2, 10)
+    truth = @. (3.0 + X[2, :])^2
+    @test all(truth .≈ tree(X, operators))
+end