feat: add LiteSVM tests for favorites anchor program

- Implement tests for writing, updating, and validating favorite data on the blockchain.
- Ensure unauthorized transactions are rejected correctly.
- Utilize LiteSVM for transaction simulation and account state verification.

Author: sol-warrior

basics/favorites/anchor/tests/litesvm.test.ts

@@ -0,0 +1,143 @@
+import anchor from "@coral-xyz/anchor";
+import {
+	Keypair,
+	PublicKey,
+	SystemProgram,
+	Transaction,
+	TransactionInstruction,
+} from "@solana/web3.js";
+import { assert } from "chai";
+import { LiteSVM } from "litesvm";
+
+import IDL from "../target/idl/favorites.json" with { type: "json" };
+
+describe("LiteSVM: Favorites", () => {
+	const svm = new LiteSVM();
+	const programId = new PublicKey(IDL.address);
+	const coder = new anchor.BorshCoder(IDL as anchor.Idl); //For serialization and deserialization
+	const payer = Keypair.generate();
+	svm.airdrop(payer.publicKey, BigInt(1000000000));
+
+	const programPath = new URL("../target/deploy/favorites.so", import.meta.url)
+		.pathname;
+	svm.addProgramFromFile(programId, programPath);
+
+	const [favPdaAccount] = PublicKey.findProgramAddressSync(
+		[Buffer.from("favorites"), payer.publicKey.toBuffer()],
+		programId,
+	);
+	/**
+	 * Here's what we want to write to the blockchain
+	 */
+	const favoriteNumber = new anchor.BN(23);
+	const favoriteColor = "purple";
+	const favoriteHobbies = ["skiing", "skydiving", "biking"];
+
+	it("Writes our favorites to the blockchain", () => {
+		const ixArgs = {
+			number: favoriteNumber,
+			color: favoriteColor,
+			hobbies: favoriteHobbies,
+		};
+
+		const data = coder.instruction.encode("set_favorites", ixArgs);
+		const ix = new TransactionInstruction({
+			keys: [
+				{ pubkey: payer.publicKey, isSigner: true, isWritable: true },
+				{ pubkey: favPdaAccount, isSigner: false, isWritable: true },
+				{ pubkey: SystemProgram.programId, isSigner: false, isWritable: false },
+			],
+			programId,
+			data,
+		});
+
+		const tx = new Transaction().add(ix);
+		tx.feePayer = payer.publicKey;
+		tx.recentBlockhash = svm.latestBlockhash();
+		tx.sign(payer);
+		svm.sendTransaction(tx);
+
+		/**
+		 * Fetch the account and check its favorites
+		 */
+		const favAccountInfo = svm.getAccount(favPdaAccount);
+		const favAccount = coder.accounts.decode(
+			"Favorites",
+			Buffer.from(favAccountInfo.data),
+		);
+
+		assert.equal(favAccount.number.toNumber(), favoriteNumber.toNumber());
+		assert.equal(favAccount.color, favoriteColor);
+		assert.deepStrictEqual(favAccount.hobbies, favoriteHobbies);
+	});
+
+	it("Updates the favorites", () => {
+		const newFavoriteHobbies = ["coding", "reading", "biking", "swimming"];
+		const ixArgs = {
+			number: favoriteNumber,
+			color: favoriteColor,
+			hobbies: newFavoriteHobbies,
+		};
+
+		const data = coder.instruction.encode("set_favorites", ixArgs);
+		const ix = new TransactionInstruction({
+			keys: [
+				{ pubkey: payer.publicKey, isSigner: true, isWritable: true },
+				{ pubkey: favPdaAccount, isSigner: false, isWritable: true },
+				{ pubkey: SystemProgram.programId, isSigner: false, isWritable: false },
+			],
+			programId,
+			data,
+		});
+
+		const tx = new Transaction().add(ix);
+		tx.feePayer = payer.publicKey;
+		tx.recentBlockhash = svm.latestBlockhash();
+		tx.sign(payer);
+		svm.sendTransaction(tx);
+
+		/**
+		 * Fetch the account and check its favorites
+		 */
+		const favAccountInfo = svm.getAccount(favPdaAccount);
+		const favAccount = coder.accounts.decode(
+			"Favorites",
+			Buffer.from(favAccountInfo.data),
+		);
+
+		assert.equal(favAccount.number.toNumber(), favoriteNumber.toNumber());
+		assert.equal(favAccount.color, favoriteColor);
+		assert.deepStrictEqual(favAccount.hobbies, newFavoriteHobbies);
+	});
+
+	it("Rejects transactions from unauthorized signers", () => {
+		const newFavoriteHobbies = ["coding", "reading", "biking"];
+		const someRandomGuy = Keypair.generate();
+
+		const ixArgs = {
+			number: favoriteNumber,
+			color: favoriteColor,
+			hobbies: newFavoriteHobbies,
+		};
+
+		const data = coder.instruction.encode("set_favorites", ixArgs);
+		const ix = new TransactionInstruction({
+			keys: [
+				{ pubkey: payer.publicKey, isSigner: true, isWritable: true },
+				{ pubkey: favPdaAccount, isSigner: false, isWritable: true },
+				{ pubkey: SystemProgram.programId, isSigner: false, isWritable: false },
+			],
+			programId,
+			data,
+		});
+
+		const tx = new Transaction().add(ix);
+		tx.feePayer = payer.publicKey;
+		tx.recentBlockhash = svm.latestBlockhash();
+
+		assert.Throw(() => {
+			tx.sign(someRandomGuy);
+			svm.sendTransaction(tx);
+		}, "unknown signer");
+	});
+});