EtherFi rate provider

contracts/providers/EtherFiRateProvider.vy

@@ -0,0 +1,14 @@
+# @version 0.3.7
+
+interface EtherFiLiquidityPool:
+    def amountForShare(_shares: uint256) -> uint256: view
+
+ASSET: constant(address) = 0xCd5fE23C85820F7B72D0926FC9b05b43E359b7ee # weETH
+LIQUIDITY_POOL: constant(address) = 0x308861A430be4cce5502d0A12724771Fc6DaF216
+UNIT: constant(uint256) = 1_000_000_000_000_000_000
+
+@external
+@view
+def rate(_asset: address) -> uint256:
+    assert _asset == ASSET
+    return EtherFiLiquidityPool(LIQUIDITY_POOL).amountForShare(UNIT)

tests/test_etherfi_rate_provider.py

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+from ape import Contract
+import pytest
+
+ASSET = '0xCd5fE23C85820F7B72D0926FC9b05b43E359b7ee'
+UNDERLYING = '0x35fA164735182de50811E8e2E824cFb9B6118ac2'
+UNIT = 1_000_000_000_000_000_000
+
+@pytest.fixture
+def provider(project, deployer):
+    return project.EtherFiRateProvider.deploy(sender=deployer)
+
+def test_rate_provider(provider, accounts):
+    asset = Contract(ASSET)
+    account = accounts['0x2b0024ecee0626E9cFB5F0195F69DCaC5b759Dc9']
+    underlying = Contract(UNDERLYING)
+    rate = provider.rate(ASSET)
+    asset.unwrap(UNIT, sender=account)
+    assert rate > UNIT and rate < UNIT * 12 // 10
+    assert abs(underlying.balanceOf(account) - rate) <= 1 # rounding difference due to rebase mechanism