Remove extra tests

Author: MilesCranmer

test/test_simplification.jl

@@ -90,20 +90,6 @@ output3, flag3 = eval_tree_array(tree_copy2, X, operators)
 # so we weaken the requirement:
 @test isapprox(output1, output3, atol=1e-2 * sqrt(N))
 
-# Test that simplification (within the library) preserves shared nodes:
-operators = OperatorEnum(; binary_operators=(+, -, *, /))
-base_tree = Node(1, Node(; val=0.3), Node(; val=0.2))
-tree = x1 * base_tree + base_tree
-simplify_tree(tree, operators; preserve_sharing=true)
-@test tree.l.r === tree.r
-
-base_tree = (x1 + Node(; val=0.3)) + Node(; val=0.2)
-true_simplification_value = 0.5
-tree = x2 * base_tree + base_tree
-combine_operators(tree, operators; preserve_sharing=true)
-# Should not combine twice!
-@test tree.l.r.r.val == true_simplification_value
-
 ###############################################################################
 ## Hit other parts of `simplify_tree` and `combine_operators` to increase
 ## code coverage: