hdkeychain: Use mock net params in tests.

This implements a mock network params struct that implements the new
interface and modifies the test code to make use of the mock params
instead of chaincfg.  This completely decouples the tests, with the
exception of the example code, from chaincfg and therefore any updates
to it such as introducing new test networks will not require changes to
the tests.

hdkeychain/bench_test.go

@@ -7,8 +7,6 @@ package hdkeychain
 
 import (
 	"testing"
-
-	"github.com/decred/dcrd/chaincfg"
 )
 
 // bip0032MasterPriv1 is the master private extended key from the first set of
@@ -20,8 +18,7 @@ const bip0032MasterPriv1 = "dprv3hCznBesA6jBtmoyVFPfyMSZ1qYZ3WdjdebquvkEfmRfx" +
 // child from a master private extended key.
 func BenchmarkDeriveHardened(b *testing.B) {
 	b.StopTimer()
-	masterKey, err := NewKeyFromString(bip0032MasterPriv1,
-		&chaincfg.MainNetParams)
+	masterKey, err := NewKeyFromString(bip0032MasterPriv1, mockMainNetParams())
 	if err != nil {
 		b.Errorf("Failed to decode master seed: %v", err)
 	}
@@ -36,8 +33,7 @@ func BenchmarkDeriveHardened(b *testing.B) {
 // (non-hardened) child from a master private extended key.
 func BenchmarkDeriveNormal(b *testing.B) {
 	b.StopTimer()
-	masterKey, err := NewKeyFromString(bip0032MasterPriv1,
-		&chaincfg.MainNetParams)
+	masterKey, err := NewKeyFromString(bip0032MasterPriv1, mockMainNetParams())
 	if err != nil {
 		b.Errorf("Failed to decode master seed: %v", err)
 	}
@@ -52,8 +48,7 @@ func BenchmarkDeriveNormal(b *testing.B) {
 // key to a public extended key.
 func BenchmarkPrivToPub(b *testing.B) {
 	b.StopTimer()
-	masterKey, err := NewKeyFromString(bip0032MasterPriv1,
-		&chaincfg.MainNetParams)
+	masterKey, err := NewKeyFromString(bip0032MasterPriv1, mockMainNetParams())
 	if err != nil {
 		b.Errorf("Failed to decode master seed: %v", err)
 	}
@@ -67,8 +62,9 @@ func BenchmarkPrivToPub(b *testing.B) {
 // BenchmarkDeserialize benchmarks how long it takes to deserialize a private
 // extended key.
 func BenchmarkDeserialize(b *testing.B) {
+	mainNetParams := mockMainNetParams()
 	for i := 0; i < b.N; i++ {
-		NewKeyFromString(bip0032MasterPriv1, &chaincfg.MainNetParams)
+		NewKeyFromString(bip0032MasterPriv1, mainNetParams)
 	}
 }
 
@@ -76,8 +72,7 @@ func BenchmarkDeserialize(b *testing.B) {
 // extended key.
 func BenchmarkSerialize(b *testing.B) {
 	b.StopTimer()
-	masterKey, err := NewKeyFromString(bip0032MasterPriv1,
-		&chaincfg.MainNetParams)
+	masterKey, err := NewKeyFromString(bip0032MasterPriv1, mockMainNetParams())
 	if err != nil {
 		b.Errorf("Failed to decode master seed: %v", err)
 	}

hdkeychain/extendedkey_test.go

@@ -15,10 +15,51 @@ import (
 	"errors"
 	"reflect"
 	"testing"
-
-	"github.com/decred/dcrd/chaincfg"
 )
 
+// mockNetParams implements the NetworkParams interface and is used throughout
+// the tests to mock multiple networks.
+type mockNetParams struct {
+	privKeyID [4]byte
+	pubKeyID  [4]byte
+}
+
+// HDPrivKeyVersion returns the extended private key version bytes associated
+// with the mock params.
+//
+// This is part of the NetworkParams interface.
+func (p *mockNetParams) HDPrivKeyVersion() [4]byte {
+	return p.privKeyID
+}
+
+// HDPubKeyVersion returns the extended public key version bytes associated with
+// the mock params.
+//
+// This is part of the NetworkParams interface.
+func (p *mockNetParams) HDPubKeyVersion() [4]byte {
+	return p.pubKeyID
+}
+
+// mockMainNetParams returns mock mainnet parameters to use throughout the
+// tests.  They match the Decred mainnet params as of the time this comment was
+// written.
+func mockMainNetParams() *mockNetParams {
+	return &mockNetParams{
+		privKeyID: [4]byte{0x02, 0xfd, 0xa4, 0xe8}, // starts with dprv
+		pubKeyID:  [4]byte{0x02, 0xfd, 0xa9, 0x26}, // starts with dpub
+	}
+}
+
+// mockTestNetParams returns mock testnet parameters to use throughout the
+// tests.  They match the Decred testnet version 3 params as of the time this
+// comment was written.
+func mockTestNetParams() *mockNetParams {
+	return &mockNetParams{
+		privKeyID: [4]byte{0x04, 0x35, 0x83, 0x97}, // starts with tprv
+		pubKeyID:  [4]byte{0x04, 0x35, 0x87, 0xd1}, // starts with tpub
+	}
+}
+
 // TestBIP0032Vectors tests the vectors provided by [BIP32] to ensure the
 // derivation works as intended.
 func TestBIP0032Vectors(t *testing.T) {
@@ -27,15 +68,15 @@ func TestBIP0032Vectors(t *testing.T) {
 	testVec2MasterHex := "fffcf9f6f3f0edeae7e4e1dedbd8d5d2cfccc9c6c3c0bdbab7b4b1aeaba8a5a29f9c999693908d8a8784817e7b7875726f6c696663605d5a5754514e4b484542"
 	hkStart := uint32(0x80000000)
 
-	mainNetParams := &chaincfg.MainNetParams
-	testNetParams := &chaincfg.TestNet3Params
+	mainNetParams := mockMainNetParams()
+	testNetParams := mockTestNetParams()
 	tests := []struct {
 		name     string
 		master   string
 		path     []uint32
 		wantPub  string
 		wantPriv string
-		net      *chaincfg.Params
+		net      NetworkParams
 	}{
 		// Test vector 1
 		{
@@ -346,7 +387,7 @@ func TestPrivateDerivation(t *testing.T) {
 		},
 	}
 
-	mainNetParms := &chaincfg.MainNetParams
+	mainNetParms := mockMainNetParams()
 tests:
 	for i, test := range tests {
 		extKey, err := NewKeyFromString(test.master, mainNetParms)
@@ -466,7 +507,7 @@ func TestPublicDerivation(t *testing.T) {
 		},
 	}
 
-	mainNetParams := &chaincfg.MainNetParams
+	mainNetParams := mockMainNetParams()
 tests:
 	for i, test := range tests {
 		extKey, err := NewKeyFromString(test.master, mainNetParams)
@@ -563,7 +604,7 @@ func TestExtendedKeyAPI(t *testing.T) {
 		},
 	}
 
-	mainNetParams := &chaincfg.MainNetParams
+	mainNetParams := mockMainNetParams()
 	for i, test := range tests {
 		key, err := NewKeyFromString(test.extKey, mainNetParams)
 		if err != nil {
@@ -631,7 +672,7 @@ func TestExtendedKeyAPI(t *testing.T) {
 // the errors are handled properly.
 func TestErrors(t *testing.T) {
 	// Should get an error when seed has too few bytes.
-	net := &chaincfg.MainNetParams
+	net := mockMainNetParams()
 	_, err := NewMaster(bytes.Repeat([]byte{0x00}, 15), net)
 	if err != ErrInvalidSeedLen {
 		t.Errorf("NewMaster: mismatched error -- got: %v, want: %v",
@@ -699,7 +740,7 @@ func TestErrors(t *testing.T) {
 		},
 	}
 
-	mainNetParams := &chaincfg.MainNetParams
+	mainNetParams := mockMainNetParams()
 	for i, test := range tests {
 		extKey, err := NewKeyFromString(test.key, mainNetParams)
 		if !reflect.DeepEqual(err, test.err) {
@@ -723,12 +764,12 @@ func TestErrors(t *testing.T) {
 
 // TestZero ensures that zeroing an extended key works as intended.
 func TestZero(t *testing.T) {
-	mainNetParams := &chaincfg.MainNetParams
+	mainNetParams := mockMainNetParams()
 	tests := []struct {
 		name   string
 		master string
 		extKey string
-		net    *chaincfg.Params
+		net    NetworkParams
 	}{
 		// Test vector 1
 		{