fix: throw on negative param cairo.uint256 and bnToUint256

__tests__/utils/uint256.test.ts

@@ -1,6 +1,29 @@
+import { cairo } from '../../src';
 import { UINT_128_MAX, UINT_256_MAX, bnToUint256, uint256ToBN } from '../../src/utils/uint256';
 
 describe('cairo uint256', () => {
+  test('bnToUint256 should not convert -1 from BN to uint256 struct', () => {
+    expect(() => {
+      bnToUint256(-1n);
+    }).toThrow('uint256 must be positive number');
+  });
+
+  test('uint256 should not convert -1 to uint256 hex-string struct', () => {
+    expect(() => {
+      cairo.uint256(-1n);
+    }).toThrow('uint256 must be positive number');
+  });
+
+  test('uint256 should not convert -1 to uint256 dec struct', () => {
+    const uint256 = cairo.uint256(1000n);
+    expect(uint256).toMatchInlineSnapshot(`
+      Object {
+        "high": "0",
+        "low": "1000",
+      }
+    `);
+  });
+
   test('should convert 0 from BN to uint256 struct', () => {
     const uint256 = bnToUint256(0n);
     expect(uint256).toMatchInlineSnapshot(`

src/utils/calldata/cairo.ts

@@ -100,6 +100,7 @@ export function getAbiContractVersion(abi: Abi): ContractVersion {
  */
 export const uint256 = (it: BigNumberish): Uint256 => {
   const bn = BigInt(it);
+  if (bn < 0) throw Error('uint256 must be positive number');
   if (!isUint256(bn)) throw new Error('Number is too large');
   return {
     // eslint-disable-next-line no-bitwise

src/utils/uint256.ts

@@ -27,7 +27,8 @@ export function isUint256(bn: BigNumberish): boolean {
  * Convert BigNumberish (string | number | bigint) to Uint256 (hex)
  */
 export function bnToUint256(bn: BigNumberish): Uint256 {
-  const bi = toBigInt(bn);
+  const bi = BigInt(bn);
+  if (bi < 0) throw Error('uint256 must be positive number');
   if (!isUint256(bi)) throw new Error('Number is too large');
   return {
     low: addHexPrefix((bi & UINT_128_MAX).toString(16)),