Replace STBLTEST with USDC in testnet demos (#10)

* chore(USDC): add token and adapter addresses

* chore(USDC): fix token and adapter addresses

Previously mistakenly only changed variable names, but not addresses.

* nit(constants): adds comments for better readability

* nit(constants): fix typo

* docs(README): remove STBLTEST disclaimer and other

- Adds usage examples for each demo
- Adds a little more context in places for better readability

README.md

@@ -1,13 +1,7 @@
-> [!WARNING]
-> Currently this demo only works with the `STBLTEST` adapter and token, for which there is no
-> public faucet. If and when USDC deploys the adapter and the Celo community votes to make USDC an 
-> accepted fee currency, we'll have to update the addresses in [`constants.ts`](./constants.ts).
-
 # Fee Currencies on Celo
 
 > [!TIP] 
-> Code examples for
-> [docs.celo.org > Paying for Gas in Tokens](https://docs.celo.org/protocol/transaction/erc20-transaction-fees#alfajores-testnet).
+> Code examples for [docs.celo.org > Paying for Gas in Tokens](https://docs.celo.org/protocol/transaction/erc20-transaction-fees#alfajores-testnet).
 > Visit that page for more information.
 
 Fee currency transactions are unique to Celo. Fee currency transactions are made using a custom
@@ -22,28 +16,55 @@ JS/TS client libraries.
 
 ### `viem` (Recommended ✅)
 
-We recommend you build with `viem`, if you are starting from scratch. See demo in
-[`viem.ts`](/viem.ts).
+We recommend you build with `viem`, if you are starting from scratch. For a demo, see
+[`viem.ts`](/viem.ts). You can run the demo as follows:
+
+```sh
+$ yarn ts-node viem.ts
+
+Initiating fee currency transaction...
+USDC balance of 0x303C22e6ef01CbA9d03259248863836CB91336D5: 10
+Done! Transaction hash: 0x5242bb5340baa534f14285feac24fd8eac57cdd779b9a5cb2e88bbb5c3e6bb3d
+✨  Done in 4.66s.
+```
 
 ### `web3js` + `@celo/connect` (Discouraged ❌)
 
-We don't recommend you build with `web3js` and `@celo/connect`, if you are starting from scratch.
+To make fee currency transactions with `web3js` you need to use it in conjunction with
+`@celo/connect`. Bu, we don't recommend you build with `web3js` and `@celo/connect`, if you are
+starting from scratch. That's because `@celo/connect` only supports `[email protected]`, and not the 
+latest version `[email protected]`. Instead, we recommend you build with `viem`. 
 
-That's because `@celo/connect` only supports `[email protected]`, and not the latest version
-`[email protected]`.
+But, for completeness, we included a demo in
+[`web3.ts`](/web3.ts) so you can see usage patterns. You can run the demo as follows:
 
-Instead, we recommend you build with `viem`. But, for completeness, we included a demo in
-[`web3.ts`](/web3.ts) so you can see usage patterns.
+```sh
+$ yarn ts-node web3.ts
+
+Initiating fee currency transaction...
+USDC balance of 0x303c22e6ef01cba9d03259248863836cb91336d5: 9.989236
+Done! Transaction hash: 0x49fa99caa6c2a4aade1d3a979fedea5037542a7a7a39c70eeec14b7661a9b030
+✨  Done in 4.78s.
+```
 
 ### `@celo/contractkit` (Discouraged ❌)
 
 We don't recommend you build with `@celo/contractkit`, if you are starting from scratch.
-
 That's because `@celo/contractkit` is a library for developers who want to interact with
 [core contracts](https://docs.celo.org/contract-addresses) like `Governance.sol` or `Election.sol`.
+Instead, we recommend you build with `viem`. 
+
+But, for completeness, we included a demo in [`contractkit.ts`](/contractkit.ts) so you can see 
+usage patterns. You can run the demo as follows:
+
+```sh
+$ yarn ts-node contractkit.ts
 
-Instead, we recommend you build with `viem`. But, for completeness, we included a demo in
-[`contractkit.ts`](/contractkit.ts) so you can see usage patterns.
+Initiating fee currency transaction...
+USDC balance of 0x303C22e6ef01CbA9d03259248863836CB91336D5: 9.957260999999999
+Done! Transaction hash: 0x6a2c32283971ca90463fb58b00d4fe4c4d75b340bc3f646667a4bdc368f31a65
+✨  Done in 5.85s.
+```
 
 ### Raw transaction (Experts-only 🟠)
 
@@ -57,22 +78,20 @@ envelopes.
 But, if you would really like to construct fee currency transactions this way, you can learn more
 about the transaction arguments and format here: `celo-org/txtypes`.
 
-## Demo usage
+## Demos
 
 ### Requirements
 
 -   The private key of a Celo wallet with at least 1 USDC on the Alfajores testnet (you can get free
     USDC testnet tokens from [faucet.circle.com](https://faucet.circle.com/))
 
-### Installing Node.js
-
-We use [Node.js](https://nodejs.org/en/) to run the project locally. You need to install the
-**Node.js version** specified in [.nvmrc](./.nvmrc). To do so, run:
+-   We use [Node.js](https://nodejs.org/en/) to run the project locally. You need to install the
+    **Node.js version** specified in [.nvmrc](./.nvmrc). To do so, run:
 
-```sh
-$ nvm install
-$ nvm use
-```
+    ```sh
+    $ nvm install
+    $ nvm use
+    ```
 
 ### Installing dependencies
 
@@ -109,7 +128,7 @@ When you execute a script, you will see something akin to this output:
 $ yarn ts-node viem.ts
 
 Initiating fee currency transaction...
-STBLTEST balance of 0x303C22e6ef01CbA9d03259248863836CB91336D5: 59.946671
-Done! Transaction hash: 0x8646968a8fe025fc7fd47a4e754953ddb4fe2936b43c06d82313463cb7851071
-✨  Done in 8.23s.
+USDC balance of 0x303C22e6ef01CbA9d03259248863836CB91336D5: 10
+Done! Transaction hash: 0x5242bb5340baa534f14285feac24fd8eac57cdd779b9a5cb2e88bbb5c3e6bb3d
+✨  Done in 4.66s.
 ```

constants.ts

@@ -1,9 +1,24 @@
 import "dotenv/config";
 
-export const RECIPIENT = "0x22579CA45eE22E2E16dDF72D955D6cf4c767B0eF"; // arbitrary address
-export const cUSD_CONTRACT_ADDRESS = "0x874069Fa1Eb16D44d622F2e0Ca25eeA172369bC1"; // ERC20
-export const USDC_CONTRACT_ADDRESS = "0x780c1551C2Be3ea3B1f8b1E4CeDc9C3CE40da24E"; // ERC20
-export const USDC_ADAPTER_ADDRESS = "0xDB93874fE111F5a87Acc11Ff09Ee9450Ac6509AE"; // Adapter
+/**
+ * Arbitrary recipient address. Feel free to change this to any address you like.
+ */
+export const RECIPIENT = "0x22579CA45eE22E2E16dDF72D955D6cf4c767B0eF";
+
+/**
+ * cUSD: Fee currency that doesn't require an adapter
+ */
+export const cUSD_TOKEN_ADDRESS = "0x874069Fa1Eb16D44d622F2e0Ca25eeA172369bC1";
+
+/**
+ * USDC: Fee currency that requires an adapter
+ */
+export const USDC_TOKEN_ADDRESS = "0x2F25deB3848C207fc8E0c34035B3Ba7fC157602B";
+export const USDC_ADAPTER_ADDRESS = "0x4822e58de6f5e485eF90df51C41CE01721331dC0";
+
+/**
+ * Private key of the account that will send the demo transaction
+ */
 export const PRIVATE_KEY = process.env.PRIVATE_KEY;
 if (!PRIVATE_KEY) {
     throw new Error(

contractkit.ts

@@ -1,5 +1,5 @@
 import { newKit } from "@celo/contractkit";
-import { PRIVATE_KEY, RECIPIENT, USDC_CONTRACT_ADDRESS, USDC_ADAPTER_ADDRESS } from "./constants";
+import { PRIVATE_KEY, RECIPIENT, USDC_TOKEN_ADDRESS, USDC_ADAPTER_ADDRESS } from "./constants";
 import { ERC20ABI } from "./erc20Abi";
 import { AbiItem, CeloTxReceipt } from "@celo/connect";
 
@@ -12,7 +12,7 @@ kit.connection.addAccount(`0x${PRIVATE_KEY}`);
 /**
  *  Set up ERC20 contract
  */
-const contract = new kit.web3.eth.Contract(ERC20ABI as AbiItem[], USDC_CONTRACT_ADDRESS);
+const contract = new kit.web3.eth.Contract(ERC20ABI as AbiItem[], USDC_TOKEN_ADDRESS);
 
 /**
  * Makes a transaction to transfer ERC20 tokens using a fee currency
@@ -39,7 +39,7 @@ async function erc20Transfer() {
     const transactionReceipt = (await kit
         .sendTransaction({
             from: sender,
-            to: USDC_CONTRACT_ADDRESS,
+            to: USDC_TOKEN_ADDRESS,
             feeCurrency: USDC_ADAPTER_ADDRESS,
             data: transactionObject.encodeABI(),
         })

viem.ts

@@ -12,7 +12,7 @@ import { celoAlfajores } from "viem/chains";
 import {
     PRIVATE_KEY,
     RECIPIENT,
-    USDC_CONTRACT_ADDRESS,
+    USDC_TOKEN_ADDRESS,
     USDC_ADAPTER_ADDRESS,
 } from "./constants";
 
@@ -33,7 +33,7 @@ const sender = privateKeyToAccount(`0x${PRIVATE_KEY}`);
  *  Set up ERC20 contract
  */
 const contract = getContract({
-    address: USDC_CONTRACT_ADDRESS,
+    address: USDC_TOKEN_ADDRESS,
     abi: erc20Abi,
     client: { public: read, wallet: write },
 });

web3.ts

@@ -4,7 +4,7 @@ import { LocalWallet } from "@celo/wallet-local";
 import "dotenv/config";
 import { AbiItem } from "web3-utils";
 import { ERC20ABI } from "./erc20Abi";
-import { PRIVATE_KEY, RECIPIENT, USDC_CONTRACT_ADDRESS, USDC_ADAPTER_ADDRESS } from "./constants";
+import { PRIVATE_KEY, RECIPIENT, USDC_TOKEN_ADDRESS, USDC_ADAPTER_ADDRESS } from "./constants";
 
 /**
  * Boilerplate to create a web3js client and web3js-compatible wallet
@@ -18,7 +18,7 @@ const connection = new Connection(web3, celoWallet);
 /**
  *  Set up ERC20 contract
  */
-const contract = new web3.eth.Contract(ERC20ABI as AbiItem[], USDC_CONTRACT_ADDRESS);
+const contract = new web3.eth.Contract(ERC20ABI as AbiItem[], USDC_TOKEN_ADDRESS);
 
 /**
  * Makes a transaction to transfer ERC20 tokens using a fee currency
@@ -41,7 +41,7 @@ async function erc20Transfer() {
     const transactionReceipt = (await connection
         .sendTransaction({
             from: sender,
-            to: USDC_CONTRACT_ADDRESS,
+            to: USDC_TOKEN_ADDRESS,
             feeCurrency: USDC_ADAPTER_ADDRESS,
             data: transactionObject.encodeABI(),
         })