math_test.go

package keeper

import (
	"testing"

	sdk "github.com/cosmos/cosmos-sdk/types"

	"github.com/stretchr/testify/require"
)

func TestCalcSpotPrice(t *testing.T) {
	// TODO: Change test to be table driven
	tokenBalanceIn, err := sdk.NewDecFromStr("100")
	require.NoError(t, err)
	tokenWeightIn, err := sdk.NewDecFromStr("0.1")
	require.NoError(t, err)
	tokenBalanceOut, err := sdk.NewDecFromStr("200")
	require.NoError(t, err)
	tokenWeightOut, err := sdk.NewDecFromStr("0.3")
	require.NoError(t, err)

	actual_spot_price := calcSpotPrice(tokenBalanceIn, tokenWeightIn, tokenBalanceOut, tokenWeightOut)
	// s = (100/.1) / (200 / .3) = (1000) / (2000 / 3) = 1.5
	expected_spot_price, err := sdk.NewDecFromStr("1.5")
	require.NoError(t, err)

	// assert that the spot prices are within the error margin from one another.
	require.True(
		t,
		expected_spot_price.Sub(actual_spot_price).Abs().LTE(powPrecision),
		"expected value & actual value's difference should less than precision",
	)

}

// TODO: Create test vectors with balancer contract
func TestCalcSpotPriceWithSwapFee(t *testing.T) {
	tokenBalanceIn, err := sdk.NewDecFromStr("100")
	require.NoError(t, err)
	tokenWeightIn, err := sdk.NewDecFromStr("0.1")
	require.NoError(t, err)
	tokenBalanceOut, err := sdk.NewDecFromStr("200")
	require.NoError(t, err)
	tokenWeightOut, err := sdk.NewDecFromStr("0.3")
	require.NoError(t, err)
	swapFee, err := sdk.NewDecFromStr("0.01")
	require.NoError(t, err)

	s := calcSpotPriceWithSwapFee(tokenBalanceIn, tokenWeightIn, tokenBalanceOut, tokenWeightOut, swapFee)

	expectedDec, err := sdk.NewDecFromStr("1.51515151")
	require.NoError(t, err)

	require.True(
		t,
		expectedDec.Sub(s).Abs().LTE(powPrecision),
		"expected value & actual value's difference should less than precision",
	)

}

func TestCalcOutGivenIn(t *testing.T) {

	tokenBalanceIn, err := sdk.NewDecFromStr("100")
	require.NoError(t, err)
	tokenWeightIn, err := sdk.NewDecFromStr("0.1")
	require.NoError(t, err)
	tokenBalanceOut, err := sdk.NewDecFromStr("200")
	require.NoError(t, err)
	tokenWeightOut, err := sdk.NewDecFromStr("0.3")