Adapt test parentheses

Author: asterycs

test/StdTest.jl

@@ -353,7 +353,7 @@ end
     @test to_std_string(gradient(sum(x .^ 3), x)) == "3x²"
     @test to_std_string(gradient(sum(x)^2, x)) == "2sum(xᵀ)vec(1)"
     @test to_std_string(gradient(sum((x + y) .^ 2), x)) == "2(x + y)"
-    @test to_std_string(gradient(sum((x .* y) .^ 2), x)) == "2x ⊙ y ⊙ y"
+    @test to_std_string(gradient(sum((x .* y) .^ 2), x)) == "2(x ⊙ y ⊙ y)"
     @test to_std_string(gradient(sum((A * x - y) .^ 2), x)) == "2Aᵀ(Ax - y)"
     @test to_std_string(gradient((x' * A * x) ^ (-2), x)) == "(-2)(xᵀAᵀx)⁻³(Aᵀx + Ax)"
     @test to_std_string(gradient(((A .* B) * C * x)' * x, x)) == "(A ⊙ B)Cx + Cᵀ(Aᵀ ⊙ Bᵀ)x"