diff --git a/tests/simplification_test.rs b/tests/simplification_test.rs
index a11e917..51610c5 100644
--- a/tests/simplification_test.rs
+++ b/tests/simplification_test.rs
@@ -1,47 +1,64 @@
 use polars::prelude::*;
-use rush::gp::args::PushArgs;
 use rush::gp::simplification::auto_simplify_plushy;
+use rush::gp::utils::polars_to_gene;
 use rush::instructions::numeric::*;
+use rush::push::interpreter::interpret_program;
 use rush::push::state::Gene;
 use rush::push::utils::most_genes;
+use rush::{gp::args::PushArgs, push::state::EMPTY_STATE};
+use rust_decimal::prelude::FromPrimitive;
 use rust_decimal::{Decimal, dec};
 
+/// This is a prototype for an error function. I'm hoping to have some of this
+/// refined later.
 fn test_error_function(
-    _push_args: &PushArgs,
+    push_args: &PushArgs,
     data: &DataFrame,
-    _push_program: Vec<Gene>,
+    push_program: Vec<Gene>,
 ) -> Vec<Decimal> {
-    let err_vec: Vec<Decimal> = vec![];
+    let mut error_vec: Vec<Decimal> = vec![];
 
-    let y = data.column("y").unwrap();
+    let y = data
+        .column("y")
+        .unwrap()
+        .i32()
+        .unwrap()
+        .into_iter()
+        .map(|opt| opt.map(|v| v as i128))
+        .collect::<Option<Vec<_>>>()
+        .unwrap(); // How to convert a series to a vector everybody
     let x = data.drop("y").unwrap();
 
     // println!("x: {x:#?}");
     // println!("y: {y:#?}");
 
     for n in 0..x.height() {
+        let mut state = EMPTY_STATE;
         let mut inputs: Vec<Gene> = Vec::with_capacity(x.width());
         let row = x.get_row(n).unwrap();
         for datum in row.0.iter() {
-            // println!("{:?}", val);
-            inputs.push(match datum {
-                &AnyValue::Int32(val) => Gene::GeneInt(val as i128),
-                _ => Gene::Close,
-            });
+            inputs.push(polars_to_gene(datum))
+        }
+        state.exec.extend(push_program.clone().into_iter()); // load the program
+        state.input.extend(inputs.clone().into_iter()); // Make inputs available to the state
+        interpret_program(&mut state, push_args.step_limit, push_args.max_stack_size);
+        if let Some(top_int) = state.int.pop() {
+            error_vec.push(Decimal::from_i128((y[n] - top_int).abs()).unwrap());
+        } else {
+            error_vec.push(dec!(999999.0)) // super large error if no stack item.
         }
-        println!("{:?}", inputs);
-        inputs.clear();
     }
 
-    vec![dec!(0.0)]
+    // println!("{:?}", error_vec);
+    error_vec
 }
 
 #[test]
 fn simplification_function_test() {
     let train_df: DataFrame = df!(
-        "x0" => [1, 2, 3],
+        "x0" => [4, 5, 6],
         "x1" => [7, 8, 9],
-        "y" => [8, 10, 12],
+        "y" => [11, 13, 15],
     )
     .unwrap();
     println!("{}", train_df);
@@ -49,13 +66,16 @@ fn simplification_function_test() {
 
     // push program declaration
     let push_program: Vec<Gene> = vec![
-        Gene::StateFunc(float_tan),
+        Gene::StateFunc(int_inc),   // Should get simplified out
+        Gene::StateFunc(float_tan), // along with all these float instructions
         Gene::StateFunc(float_sub),
-        Gene::StateFunc(int_add),
+        Gene::StateFunc(int_add), // stays
         Gene::StateFunc(float_tan),
         Gene::StateFunc(float_sub),
         Gene::StateFunc(float_rem),
         Gene::StateFunc(float_inc),
+        Gene::Place(0), // stays
+        Gene::Place(1), // stays
     ];
 
     let mut args = PushArgs::new();
@@ -64,5 +84,12 @@ fn simplification_function_test() {
     args.simplification_steps = 100;
     args.error_function = Some(test_error_function);
 
-    test_error_function(&args, &train_df, push_program);
+    // test_error_function(&args, &train_df, push_program);
+
+    // test the auto simplification here
+    let simplified_genome = auto_simplify_plushy(push_program, args.error_function.unwrap(), args);
+    assert_eq!(
+        vec![Gene::StateFunc(int_add), Gene::Place(0), Gene::Place(1)],
+        simplified_genome
+    )
 }