Pharma Chain

On-chain pharmaceutical batch tracking with role-based access control. This repo focuses on smart contracts, deployment, and automated tests before any frontend work so the protocol behavior and permissions are fixed and verifiable first.

What you built (high level)

• contracts/PharmaChain.sol — A PharmaChain contract using OpenZeppelin AccessControl with manufacturer / distributor / pharmacist roles, batch storage, strict status progression, and BatchUpdated events for an audit trail.
• scripts/deploy.ts — Deploys PharmaChain (e.g. local or Sepolia via npm run deploy:sepolia).
• test/PharmaRole.test.ts — End-to-end supply-chain tests plus negative tests for invalid skips, wrong recipients, and bad status transitions.
• hardhat.config.ts — Solidity 0.8.28 with optimizer, Sepolia + Etherscan env wiring, gas reporter.
• tsconfig.json — TypeScript settings compatible with Hardhat + TypeChain (including rootDir).

Roles used (Access Control)

Role	Constant	Purpose
Admin	DEFAULT_ADMIN_ROLE (built-in)	Granted to deployer in the constructor; can grant/revoke other roles.
Manufacturer	MANUFACTURER_ROLE	Creates batches via manufactureBatch.
Distributor	DISTRIBUTOR_ROLE	Receives batch when status moves to InTransit (from manufacturer).
Pharmacist	PHARMACIST_ROLE	Receives batch when status moves to Delivered (from distributor).
Patient	(no on-chain role)	Final owner after Sold; no special role required for the recipient address in that step.

Status enum (numeric values used in tests): 0 Manufactured → 1 InTransit → 2 Delivered → 3 Sold.

transferBatch enforces: only the current owner can transfer; status must strictly increase; each step checks sender role, prior status, and recipient role where applicable (see contract comments in PharmaChain.sol).

Tools and libraries

Tool / package	Why it’s here
Hardhat	Solidity compile, local network, test runner, scripts.
@nomicfoundation/hardhat-toolbox	Bundles testing (Mocha/Chai), Ethers v6, TypeChain, coverage helpers, etc.
@openzeppelin/contracts	Battle-tested AccessControl instead of custom auth.
hardhat-gas-reporter	Optional gas / cost insight during tests (gasReporter in hardhat.config.ts).
dotenv	Loads .env for SEPOLIA_RPC_URL, PRIVATE_KEY, ETHERSCAN_API_KEY (never commit real keys).
TypeScript + TypeChain	Generated types under typechain-types/ for safer contract calls from tests/scripts.

Node.js: Hardhat officially supports current LTS Node versions. If you use an older Node (e.g. v17), you may see warnings or odd TypeScript behavior; prefer Node 20 LTS for this project.

Configuration notes (fixes you applied along the way)

1. HardhatUserConfig / solidity.settings — Optimizer and compiler settings belong under solidity: { version, settings }, not as a stray top-level settings key.
2. gasReporter.L2 — The gas reporter only accepts certain L2 presets (e.g. arbitrum); "polygon" is not in the allowed union for that option.
3. tsconfig.json → rootDir — With TypeScript 5.x and Hardhat’s layout, setting "rootDir": "." avoids TS5011 (“common source directory is ./test…”) when running hardhat test.

After changing the ABI (new functions on the contract), run npx hardhat compile so TypeChain regenerates typechain-types/ and stays in sync with PharmaChain.sol.

Test workflow

Commands

npm install          # once
npm run compile      # or: npx hardhat compile
npm test             # or: npx hardhat test

For Sepolia deployment (after filling .env):

npm run deploy:sepolia

How the tests are structured

1. beforeEach — Fresh contract each test; five signers (admin, manufacturer, distributor, pharmacist, patient); admin grants the three operational roles.
2. Happy path — One test walks the full chain: manufacture → InTransit to distributor → Delivered to pharmacist → Sold to patient; asserts final batches(batchId) owner and status.
3. Negative tests — Skip distributor, wrong recipient role, invalid status progression / regression, illegal jump to Sold.

Why Chai + Hardhat matchers

• expect(...).to.emit — Asserts the contract emitted BatchUpdated with the expected indexed args (and anyValue for timestamps you don’t need to pin exactly).
• expect(...).to.be.revertedWith(...) — Asserts require string reverts match y0 '/our security rules.

Using automated tests here catches permission and state-machine bugs before a UI exists; the frontend can then trust a stable ABI and documented flows.

Deploy script

scripts/deploy.ts uses ethers.deployContract("PharmaChain"), waits for deployment, and logs the address — that address is what you will plug into a frontend (e.g. wagmi/ethers config) later.

Suggested order: why contracts and tests before the frontend

1. Single source of truth — Rules live on-chain; the UI only reflects them.
2. Cheaper iteration — Tests run in seconds; changing Solidity after a UI is wired is slower and error-prone.
3. Clear ABI — Compile once; export address + ABI to the app when you start the frontend.
4. Security — Role and status checks are proven in tests, not only in UI validation (which can be bypassed).

Original Hardhat boilerplate (optional)

The lines below were from the sample template; this project’s real entry points are PharmaChain, test/PharmaRole.test.ts, and scripts/deploy.ts.

npx hardhat help-0-```