diff --git a/typescript/test/stableMath.test.ts b/typescript/test/stableMath.test.ts
new file mode 100644
index 0000000..1b49986
--- /dev/null
+++ b/typescript/test/stableMath.test.ts
@@ -0,0 +1,27 @@
+// pnpm test ./test/stableMath.test.ts
+
+import { _computeBalance, _computeInvariant, _computeInGivenExactOut, _computeOutGivenExactIn } from 'src/stable/stableMath.ts';
+import { describe, expect, test } from 'vitest';
+
+describe('test stableMath', () => {
+    test('_computeBalance', () => {
+        // based on this sim
+        // https://dashboard.tenderly.co/mcquardt/project/simulator/f174cf82-3525-4376-b13d-9e61bad1649c?trace=0.4.0
+        const finalBalances = _computeBalance(
+            1000000n,
+            [20099500000000000000000n,20000000000000000000000n], 
+            40000000000000000000000n, 
+            1
+        )
+        expect(finalBalances).toEqual(19900500494527739566845n)
+    })
+    test('_computeInvariant', () => {
+        // based on this sim
+        // https://dashboard.tenderly.co/mcquardt/project/simulator/f174cf82-3525-4376-b13d-9e61bad1649c?trace=0.4.0
+        const invariant = _computeInvariant(
+            1000000n,
+            [20000000000000000000000n,20000000000000000000000n]
+        )
+        expect(invariant).toEqual(40000000000000000000000n)
+    });
+})
\ No newline at end of file
diff --git a/typescript/test/stablePool.test.ts b/typescript/test/stablePool.test.ts
index deba318..99229af 100644
--- a/typescript/test/stablePool.test.ts
+++ b/typescript/test/stablePool.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, test } from 'vitest';
-import { SwapKind } from '../src/index';
+import { SwapKind, SwapParams } from '../src/index';
 import { Stable } from '../src/stable';
 
 describe('stable pool', () => {
@@ -88,4 +88,25 @@ describe('stable pool', () => {
             });
         });
     });
+    describe('onSwap matches onchain results', () => {
+        // create new pool
+        // sim https://dashboard.tenderly.co/mcquardt/project/simulator/f174cf82-3525-4376-b13d-9e61bad1649c?trace=0
+        const tempPool = new Stable({
+            amp: 1000000n
+        });
+
+        const swapParams: SwapParams = {
+            swapKind: SwapKind.GivenIn,
+            amountGivenScaled18: 99500000000000000000n,
+            balancesLiveScaled18: [
+                20000000000000000000000n,
+                20000000000000000000000n,
+            ],
+            indexIn: 0,
+            indexOut: 1,
+        };
+
+        const amountOut = tempPool.onSwap(swapParams);
+        expect(amountOut).toEqual(99499505472260433154n);
+    })
 });