fixed typos and updated readme

.gitignore

@@ -5,4 +5,6 @@ cache
 artifacts
 .env
 .openzeppelin
-package-lock.json
+package-lock.json
+coverage.json
+coverage

README.md

@@ -1,26 +1,34 @@
 # Openzeppelin upgradable smart-contract example
 
-Deploy upgradable smart contract using Openzeppelin on Polygon test network
+Deploy upgradable smart contract using Openzeppelin on local test network OR polygon test network. This example uses `Transparent Proxy` approach for deploying upgradeable smart contract.
 
 **Commands to create a new project using Hardhat**
 
 1. `mkdir openzeppelin_upgradable_sc`
 
-2. `cd hardhat_polygon_nft`
+2. `cd openzeppelin_upgradable_sc`
 
 3. `npm init --yes`
 
 4. `npm install --save-dev hardhat`
 
 5. `npx hardhat`
 
-6. Create an `.env` file and add the private-key and rpc api-key in this file. we require these keys for configuring hardhat.config.js file.
+6. Create an `.env` file by renaming `env.example` to `.env` and add the private-key and rpc api-key in this file. we require these keys for configuring hardhat.config.js file. please note that private-key and rpc api-key is only needed when using polygon_test network.
 
 7. Please add this `.env` file to `.gitignore` to avoid putting private information to github.
 
-8. Install `npm i dotenv` package to use the environment variables from `.env` file
+8. Install `npm i dotenv` package to use the environment variables from `.env` file.
 
-9. Since we are using openzeppelin then we have to add some plugins.
+9. We can add more plugins like `hardhat-gas-reporter`, `solidity-coverage` and `hardhat-solhint` using below commands.
+
+    A. `npm install hardhat-gas-reporter --save-dev`. For more info please refer [documentation](https://hardhat.org/plugins/hardhat-gas-reporter.html)
+
+    B. `npm install solidity-coverage --save-dev`. For more info please refer [documentation](https://hardhat.org/plugins/solidity-coverage.html)
+
+    C. `npm install @nomiclabs/hardhat-solhint --save-dev`. For more info please refer [documentation](https://hardhat.org/plugins/nomiclabs-hardhat-solhint.html).
+
+10. Since we are using openzeppelin then we have to add some plugins.
 
     A. `npm install @openzeppelin/contracts`
 
@@ -38,41 +46,23 @@ Deploy upgradable smart contract using Openzeppelin on Polygon test network
 
 **Deploy Project**
 
-***WARNING:*** This section requires some changes after the recent changes in the code.
+***WARNING:*** There is some issue with Polygon rpc testnet endpoints. They are not responding well when deploying the upgradeable smart-contract.
 
-1. Deploying `deployProxy` [script](https://github.com/prayagsingh/openzeppelin_upgrdabale_sc/blob/main/scripts/deployProxy_box.js) using command `npx hardhat run --network polygon_test scripts/deployProxy_box.js`. please note down the address. we will use it in Step `2.C`.
+1. Open a new terminal and start a hardhat local node using command `npx hardhat node`.
 
-2. Now interact with `Box` contract by using `Hardhat-console`. Please follow below steps.
+2. Deploying `deployProxy` [script](https://github.com/prayagsingh/openzeppelin_upgrdabale_sc/blob/main/scripts/deployProxy_box.js) using command `npx hardhat run --network localhost scripts/deployProxy_box.js`. please note down the address.
 
-    A. `npx hardhat console --network polygon_test`
-
-    B. `const Box = await ethers.getContractFactory('Box');`
-
-    C. `const box = await Box.attach('<the address of our proxy contract from when we deployed our Box contract>');`
-
-    D. `(await box.retrieve()).toString();` Result shoud be `42`. 
+3. Lets test the above smart-contract but first lets update the contract address [here](https://github.com/prayagsingh/openzeppelin_upgrdabale_sc/blob/71287be9032d9f57b1ac9e6663e76adee90137c4/scripts/execute_boxv1_func.js#L15) in `execute_boxv1_func.js` script. Now let's deploy the script using command `npx hardhat run scripts/execute_boxv1_func.js --network localhost`. It will return `13` as a value.
 
-3. Now it's time to deploy `BoxV2` smart-contract which contains additional functionality  when compared to `Box` smart-contract.
+4. Now it's time to deploy `BoxV2` smart-contract which contains additional functionality  when compared to `Box` smart-contract.
 
-4. We will be using `upgradeProxy` [script](https://github.com/prayagsingh/openzeppelin_upgrdabale_sc/blob/main/scripts/upgradeProxy_box.js) for this operation. But before deploying this script please make sure to replace the address [here](https://github.com/prayagsingh/openzeppelin_upgrdabale_sc/blob/7473f927600b716cb9265d3e5dc95d939521781b/scripts/upgradeProxy_box.js#L8) with the address created in Step 1. 
+5. We will be using `upgradeProxy` [script](https://github.com/prayagsingh/openzeppelin_upgrdabale_sc/blob/main/scripts/upgradeProxy_box.js) for this operation. But before deploying this script, please make sure to replace the address [here](https://github.com/prayagsingh/openzeppelin_upgrdabale_sc/blob/71287be9032d9f57b1ac9e6663e76adee90137c4/scripts/upgradeProxy_box.js#L8) with the contract address generated in Step 2. 
 
-5. Deploy the script using command `npx hardhat run --network polygon_test scripts/upgradeProxy_box.js`
+6. Deploy the script using command `npx hardhat run --network localhost scripts/upgradeProxy_box.js`
 
-6. Now we have successfully upgraded the smart-contract `Box` to `Boxv2` while ***keeping its state and the same address as before***.
+7. Now we have successfully upgraded the smart-contract `Box` to `Boxv2` while ***keeping its state and the same contract address as before***. Compare the output of Step 2 and Step 5. Both are using same contract address.
 
-7. Verify the upgradation using below commands.
-
-    A. `npx hardhat console --network polygon_test`
-
-    B. `const BoxV2 = await ethers.getContractFactory('BoxV2');`
-
-    C. `const box = await BoxV2.attach('< same address as in Step 2.C >');`
-
-    D. `(await box.retrieve()).toString();` Result shoud be `42`.
-
-    E. execute increment function using command `await box.increment();` 
-
-    F. `(await box.retrieve()).toString();` Result should be `43`.
+8. Now lets test the `BoxV2` smart-contract by deploying the `execute_boxv2_func.js` script. But before deploying it, update the contract address [here](https://github.com/prayagsingh/openzeppelin_upgrdabale_sc/blob/71287be9032d9f57b1ac9e6663e76adee90137c4/scripts/execute_boxv2_func.js#L15). Now lets deploy the script using command `npx hardhat run scripts/execute_boxv2_func.js --network localhost`. It will return `35` as a value.
 
 **References:** 
 

contracts/Box.sol

@@ -45,7 +45,8 @@ contract BoxV2 is Box {
     bool v2Initialized;
 
     // @note not possible to override the initialize function since it executes only once and not virtual in nature
-    // @note In upgradable smart contract we can't change anything in the Box contract. we can only add new functions and variables
+    // @note In upgradable smart contract we can't change anything in the Box contract. 
+    //       we can only add new functions and variables
     // @note https://forum.openzeppelin.com/t/understanding-upgradeable-smart-contract/15485
 
     function initializeV2() public returns (bool) {

env.example

@@ -0,0 +1,4 @@
+POLYGON_TEST_API_KEY=
+POLYGON_TEST_PRIVATE_KEY=
+METADATA_CID=
+REPORT_GAS=true

hardhat.config.js

@@ -1,6 +1,9 @@
 require("@nomiclabs/hardhat-waffle");
 require('@nomiclabs/hardhat-ethers');
 require('@openzeppelin/hardhat-upgrades');
+require("hardhat-gas-reporter");
+require("solidity-coverage");
+require("@nomiclabs/hardhat-solhint");
 
 // for using .env file which contains private info. 
 require('dotenv').config();
@@ -29,6 +32,7 @@ module.exports = {
   defaultNetwork: "hardhat",
   networks: {
     hardhat: {
+      initialBaseFeePerGas: 0, // workaround from https://github.com/sc-forks/solidity-coverage/issues/652#issuecomment-896330136 . Remove when that issue is closed.
     },
     // rinkeby: {
     //   url: "https://eth-mainnet.alchemyapi.io/v2/123abc123abc123abc123abc123abcde",
@@ -58,6 +62,12 @@ module.exports = {
       timeout: 60000,
     }
   },
+
+  gasReporter: {
+    enabled: process.env.REPORT_GAS !== undefined,
+    currency: "USD",
+  },
+
   solidity: {
     version: "0.8.4",
     settings: {
@@ -67,6 +77,7 @@ module.exports = {
       }
     }
   },
+
   paths: {
     sources: "./contracts",
     tests: "./test",