From dd6872da317b6f7abde4eb4d4d2c8c6b7b65731f Mon Sep 17 00:00:00 2001
From: "Johan T. Halseth" <johanth@gmail.com>
Date: Wed, 14 Feb 2018 08:55:03 +0100
Subject: [PATCH] lnwallet test: add TestFeeRateTypes and
 TestStaticFeeEstimator

---
 lnwallet/fee_estimator_test.go | 94 ++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 lnwallet/fee_estimator_test.go

diff --git a/lnwallet/fee_estimator_test.go b/lnwallet/fee_estimator_test.go
new file mode 100644
index 00000000..3b1d9301
--- /dev/null
+++ b/lnwallet/fee_estimator_test.go
@@ -0,0 +1,94 @@
+package lnwallet_test
+
+import (
+	"testing"
+
+	"github.com/lightningnetwork/lnd/lnwallet"
+	"github.com/roasbeef/btcutil"
+)
+
+// TestFeeRateTypes checks that converting fee rates between the
+// different types that represent fee rates and calculating fees
+// work as expected.
+func TestFeeRateTypes(t *testing.T) {
+	t.Parallel()
+
+	// Let our fee rate be 100 sat/vbyte.
+	feePerVSize := lnwallet.SatPerVByte(100)
+
+	// It is also equivalent to 25000 sat/kw.
+	feePerKw := feePerVSize.FeePerKWeight()
+	if feePerKw != 25000 {
+		t.Fatalf("expected %d sat/kw, got %d sat/kw", 25000,
+			feePerKw)
+	}
+
+	const txVSize = 300
+
+	// We'll now run through a set of values for the fee per vsize type,
+	// making sure the conversion to sat/kw and fee calculation is done
+	// correctly.
+	for f := lnwallet.SatPerVByte(0); f <= 40; f++ {
+		fPerKw := f.FeePerKWeight()
+
+		// The kw is always 250*vsize.
+		if fPerKw != lnwallet.SatPerKWeight(f*250) {
+			t.Fatalf("expected %d sat/kw, got %d sat/kw, when "+
+				"converting %d sat/vbyte", f*250, fPerKw, f)
+		}
+
+		// The tx fee should simply be f*txvsize.
+		fee := f.FeeForVSize(txVSize)
+		if fee != btcutil.Amount(f*txVSize) {
+			t.Fatalf("expected tx fee to be %d sat, was %d sat",
+				f*txVSize, fee)
+		}
+
+		// The weight is 4*vsize. Fee calculation from the fee/kw
+		// should result in the same fee.
+		fee2 := fPerKw.FeeForWeight(txVSize * 4)
+		if fee != fee2 {
+			t.Fatalf("fee calculated from vsize (%d) not equal "+
+				"fee calculated from weight (%d)", fee, fee2)
+		}
+	}
+
+	// Do the same for fee per kw.
+	for f := lnwallet.SatPerKWeight(0); f < 1500; f++ {
+		weight := int64(txVSize * 4)
+
+		// The expected fee is weight*f / 1000, since the fee is
+		// denominated per 1000 wu.
+		expFee := btcutil.Amount(weight) * btcutil.Amount(f) / 1000
+		fee := f.FeeForWeight(weight)
+		if fee != expFee {
+			t.Fatalf("expected fee to be %d sat, was %d",
+				fee, expFee)
+		}
+	}
+}
+
+// TestStaticFeeEstimator checks that the StaticFeeEstimator
+// returns the expected fee rate.
+func TestStaticFeeEstimator(t *testing.T) {
+	t.Parallel()
+
+	const feePerVSize = 100
+
+	feeEstimator := &lnwallet.StaticFeeEstimator{
+		FeeRate: feePerVSize,
+	}
+	if err := feeEstimator.Start(); err != nil {
+		t.Fatalf("unable to start fee estimator: %v", err)
+	}
+	defer feeEstimator.Stop()
+
+	feeRate, err := feeEstimator.EstimateFeePerVSize(6)
+	if err != nil {
+		t.Fatalf("unable to get fee rate: %v", err)
+	}
+
+	if feeRate != feePerVSize {
+		t.Fatalf("expected fee rate %v, got %v", feePerVSize, feeRate)
+	}
+}