foundry-protocol-exercise

Lending Protocol — Transparent Proxy pattern, inspired by Aave V2

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Struktur Project

foundry-protocol-exercise/
├── src/
│   ├── TransparentProxy.sol   ← EIP-1967 proxy (delegatecall)
│   ├── LendingPool.sol        ← Implementation V1
│   └── LendingPoolV2.sol      ← Implementation V2 (+ interest)
├── test/
│   └── LendingProtocol.t.sol  ← Full test suite
└── script/
    └── Deploy.s.sol           ← Deploy + Upgrade scripts

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Setup

forge init --no-commit  # jika belum ada
forge install foundry-rs/forge-std --no-commit
forge test -vvv

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Konsep yang Dipelajari

1. Transparent Proxy (EIP-1967)

User ──► Proxy ──delegatecall──► LendingPool (logic)
              ↑                        │
         stores state          runs code only
         (deposits, borrows)

Key insight: Kode dari LendingPool berjalan, tapi storage yang berubah adalah milik Proxy.

// Di Proxy fallback():
assembly {
    delegatecall(gas(), implementation, ...)
}

2. Storage Layout — Aturan Wajib Upgrade

Slot 0: owner          ← V1 ✓  V2 ✓  (jangan pindah!)
Slot 1: paused         ← V1 ✓  V2 ✓
Slot 2: totalDeposits  ← V1 ✓  V2 ✓
...
NEW → Slot 5: lastUpdateTimestamp  ← V2 tambah di bawah ✓

JANGAN PERNAH reorder variable saat upgrade → storage korup!

3. Protocol Logic

Deposit 4 ETH
    │
    └── maxBorrow = 4 ETH × 75% = 3 ETH
              │
              └── healthFactor = (deposit × 80%) / borrow
                                = (4 × 80) / 3 = 106 ✓ (aman)

Jika harga turun → deposit efektif < threshold:
    healthFactor < 100 → bisa dilikuidasi!

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Test Cases

Test	Yang Diuji
test_ProxyStorageIsolation	State impl selalu kosong
test_EIP1967Slots	Impl + admin di slot yang benar
test_OnlyAdminCanUpgrade	Access control upgrade
test_BorrowWithinLTV	Borrow max 75% collateral
test_Liquidation	Posisi unhealthy bisa dilikuidasi
test_UpgradePreservesState	State V1 tetap ada setelah upgrade
test_V2InterestAccrues	10% APR dihitung per detik
testFuzz_BorrowNeverExceedsLTV	Fuzz: LTV tidak pernah dilanggar

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Jalankan Test

# Semua test
forge test -vvv

# Test spesifik
forge test --match-test test_UpgradePreservesState -vvv

# Fuzz dengan lebih banyak runs
forge test --match-test testFuzz -vvv --fuzz-runs 1000

# Gas report
forge test --gas-report

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TODOs untuk Latihan Lanjutan

• Tambah ProxyAdmin contract (pisah admin dari deployer)
• Implementasi price oracle (mock Chainlink)
• Tambah ERC20 token sebagai collateral (bukan hanya ETH)
• UUPS pattern (upgrade logic di implementation, bukan proxy)
• Invariant testing: totalDeposits >= totalBorrows selalu true