solana-program-examples/tokens/token-2022/interest-bearing/anchor/tests/interest-bearing.ts

import * as anchor from "@coral-xyz/anchor";
import { Program } from "@coral-xyz/anchor";
import { InterestBearing } from "../target/types/interest_bearing";
import { TOKEN_2022_PROGRAM_ID, amountToUiAmount } from "@solana/spl-token";

describe("interest-bearing", () => {
  // Configure the client to use the local cluster.
  const provider = anchor.AnchorProvider.env();
  const connection = provider.connection;
  const wallet = provider.wallet as anchor.Wallet;
  anchor.setProvider(provider);

  const program = anchor.workspace.InterestBearing as Program<InterestBearing>;

  const mintKeypair = new anchor.web3.Keypair();

  it("Create Mint with InterestBearingConfig extension", async () => {
    const rate = 0;

    const transactionSignature = await program.methods
      .initialize(rate)
      .accounts({ mintAccount: mintKeypair.publicKey })
      .signers([mintKeypair])
      .rpc({ skipPreflight: true });
    console.log("Your transaction signature", transactionSignature);
  });

  it("Update Mint with Interest Rate", async () => {
    const rate = 100;

    const transactionSignature = await program.methods
      .updateRate(rate)
      .accounts({ mintAccount: mintKeypair.publicKey })
      .rpc({ skipPreflight: true });
    console.log("Your transaction signature", transactionSignature);
  });

  it("Calculate accrued interest", async () => {
    await sleep(1);

    const amount = 1000;
    // Convert amount to UI amount with accrued interest
    // This helper is a simulated transaction
    const uiAmount = await amountToUiAmount(
      connection,
      wallet.payer,
      mintKeypair.publicKey, // Address of the Mint account
      amount, // Amount to be converted
      TOKEN_2022_PROGRAM_ID // Token Extension Program ID
    );

    console.log("\nAmount with Accrued Interest:", uiAmount);
  });
});

function sleep(s: number) {
  return new Promise((resolve) => setTimeout(resolve, s * 1000));
}