Fix deprecated substr to substring

assembly/std/__tests__/context.spec.ts

@@ -7,6 +7,7 @@ import {
   transferredCoins,
   isDeployingContract,
   timestamp,
+  json2Address,
 } from '../context';
 import { validateAddress } from '../utils';
 
@@ -45,4 +46,20 @@ describe('Context', () => {
     const time = timestamp();
     expect(time).toBeGreaterThan(0);
   });
+
+  test('json2Address', () => {
+    const jsonString = '["address1","address2","address3"]';
+    const expectedOutput = [
+      new Address('address1'),
+      new Address('address2'),
+      new Address('address3'),
+    ];
+
+    const result = json2Address(jsonString);
+
+    expect(result.length).toBe(expectedOutput.length);
+    for (let i = 0; i < result.length; i++) {
+      expect(result[i]).toBe(expectedOutput[i]);
+    }
+  });
 });

assembly/std/context.ts

@@ -62,8 +62,8 @@ export function isDeployingContract(): bool {
  *
  * @returns An array of `Address` objects, one for each address in the input string.
  */
-function json2Address(str: string): Array<Address> {
-  str = str.substr(1, str.length - 2);
+export function json2Address(str: string): Array<Address> {
+  str = str.substring(1, str.length - 1);
 
   const a = str.split(',');
   return a.map<Address>((x) => new Address(x.substring(1, x.length - 1)));