diff --git a/examples/price_impact.py b/examples/price_impact.py index 15c3a0a6..e9c99c99 100644 --- a/examples/price_impact.py +++ b/examples/price_impact.py @@ -27,7 +27,7 @@ def usdt_to_vxv_v2(): # Compare the results with the output of: # https://app.uniswap.org/#/swap?use=v2&inputCurrency=0xdac17f958d2ee523a2206206994597c13d831ec7&outputCurrency=0x7d29a64504629172a429e64183d6673b9dacbfce - qty = 10 * 10 ** 8 + qty = 10 * 10**8 # price = uniswap.get_price_input(usdt, vxv, qty, route=route) / 10 ** 18 # print(price) @@ -38,7 +38,7 @@ def usdt_to_vxv_v2(): # The slippage for v3 (in example below) returns correct results. print(f"Impact for buying VXV on v2 with {qty / 10**8} USDT: {_perc(impact)}") - qty = 13900 * 10 ** 8 + qty = 13900 * 10**8 impact = uniswap.estimate_price_impact(usdt, vxv, qty, route=route) print(f"Impact for buying VXV on v2 with {qty / 10**8} USDT: {_perc(impact)}") @@ -49,11 +49,11 @@ def eth_to_vxv_v3(): # Compare the results with the output of: # https://app.uniswap.org/#/swap?use=v3&inputCurrency=ETH&outputCurrency=0x7d29a64504629172a429e64183d6673b9dacbfce - qty = 1 * 10 ** 18 + qty = 1 * 10**18 impact = uniswap.estimate_price_impact(eth, vxv, qty, fee=10000) print(f"Impact for buying VXV on v3 with {qty / 10**18} ETH: {_perc(impact)}") - qty = 100 * 10 ** 18 + qty = 100 * 10**18 impact = uniswap.estimate_price_impact(eth, vxv, qty, fee=10000) print(f"Impact for buying VXV on v3 with {qty / 10**18} ETH: {_perc(impact)}") diff --git a/tests/test_uniswap.py b/tests/test_uniswap.py index 12ba29c7..1e1a4b6f 100644 --- a/tests/test_uniswap.py +++ b/tests/test_uniswap.py @@ -69,6 +69,7 @@ def test_assets(client: Uniswap): """ tokens = get_tokens(client.netname) + for token_name, amount in [ ("DAI", 10_000 * ONE_DAI), ("USDC", 10_000 * ONE_USDC), @@ -133,6 +134,13 @@ def does_not_raise(): yield + +ONE_ETH = 10**18 +ONE_USDC = 10**6 + +ZERO_ADDRESS = "0x0000000000000000000000000000000000000000" + + # TODO: Change pytest.param(..., mark=pytest.mark.xfail) to the expectation/raises method @pytest.mark.usefixtures("client", "web3") class TestUniswap(object): diff --git a/uniswap/constants.py b/uniswap/constants.py index 12959a72..de6d06a5 100644 --- a/uniswap/constants.py +++ b/uniswap/constants.py @@ -78,7 +78,12 @@ MAX_TICK = -MIN_TICK # Source: https://github.com/Uniswap/v3-core/blob/v1.0.0/contracts/UniswapV3Factory.sol#L26-L31 -_tick_spacing = {100:1, 500: 10, 3_000: 60, 10_000: 200} +_tick_spacing = {100: 1, 500: 10, 3_000: 60, 10_000: 200} # Derived from (MIN_TICK//tick_spacing) >> 8 and (MAX_TICK//tick_spacing) >> 8 -_tick_bitmap_range = {100:(-3466, 3465), 500: (-347, 346), 3_000: (-58, 57), 10_000: (-18, 17)} +_tick_bitmap_range = { + 100: (-3466, 3465), + 500: (-347, 346), + 3_000: (-58, 57), + 10_000: (-18, 17), +} diff --git a/uniswap/uniswap.py b/uniswap/uniswap.py index e517eea3..47a97acd 100644 --- a/uniswap/uniswap.py +++ b/uniswap/uniswap.py @@ -33,6 +33,7 @@ encode_sqrt_ratioX96, is_same_address, nearest_tick, + realised_fee_percentage, ) from .decorators import supports, check_approval from .constants import ( @@ -1926,7 +1927,14 @@ def estimate_price_impact( cost_amount / (amount_in / (10 ** self.get_token(token_in).decimals)) ) / 10 ** self.get_token(token_out).decimals - return float((price_small - price_amount) / price_small) + # calculate and subtract the realised fees from the price impact. See: + # https://github.com/uniswap-python/uniswap-python/issues/310 + # The fee calculation will need to be updated when adding support for the AutoRouter. + price_impact_with_fees = float((price_small - price_amount) / price_small) + fee_realised_percentage = realised_fee_percentage(fee, amount_in) + price_impact_real = price_impact_with_fees - fee_realised_percentage + + return price_impact_real # ------ Exchange ------------------------------------------------------------------ @supports([1, 2]) diff --git a/uniswap/util.py b/uniswap/util.py index 761e6347..6cb7d4a2 100644 --- a/uniswap/util.py +++ b/uniswap/util.py @@ -126,3 +126,19 @@ def nearest_tick(tick: int, fee: int) -> int: def chunks(arr: Sequence[Any], n: int) -> Generator: for i in range(0, len(arr), n): yield arr[i : i + n] + + +def fee_to_fraction(fee: int): + return fee / 1000000 + + +def realised_fee_percentage(fee: int, amount_in: int) -> float: + """ + Calculate realised fee expressed as a percentage of the amount_in. + The realised fee is rounded up as fractional units cannot be used - + this correlates to how the fees are rounded by Uniswap. + """ + + fee_percentage = fee_to_fraction(fee) + fee_realised = math.ceil(amount_in * fee_percentage) + return fee_realised / amount_in