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adding changeToAddress #24

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May 7, 2021
Merged

adding changeToAddress #24

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4 changes: 2 additions & 2 deletions bscript/address.go
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Original file line number Diff line number Diff line change
Expand Up @@ -77,7 +77,7 @@ func NewAddressFromPublicKeyHash(hash []byte, mainnet bool) (*Address, error) {
if !mainnet {
bb[0] = 111
}

// nolint:makezero // stop complaining
bb = append(bb, hash...)

return &Address{
Expand All @@ -99,7 +99,7 @@ func NewAddressFromPublicKey(pubKey *bsvec.PublicKey, mainnet bool) (*Address, e
if !mainnet {
bb[0] = 111
}

// nolint:makezero // stop complaining
bb = append(bb, hash...)

return &Address{
Expand Down
62 changes: 50 additions & 12 deletions txchange.go
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Original file line number Diff line number Diff line change
Expand Up @@ -18,45 +18,83 @@ func (tx *Tx) ChangeToAddress(addr string, f []*Fee) error {
}

// Change calculates the amount of fees needed to cover the transaction
// and adds the left over change in a new output using the script provided.
// and adds the left over change in a new output using the script provided.
func (tx *Tx) Change(s *bscript.Script, f []*Fee) error {
available, hasChange, err := tx.change(s, f, true)
if err != nil {
return err
}
if hasChange {
// add rest of available sats to the change output
tx.Outputs[len(tx.Outputs)-1].Satoshis = available
}
return nil
}

// ChangeToOutput will calculate fees and add them to an output at the index specified (0 based).
// If an invalid index is supplied and error is returned.
func (tx *Tx) ChangeToOutput(index uint, f []*Fee) error {
if int(index) > len(tx.Outputs)-1 {
return errors.New("index is greater than number of inputs in transaction")
}
available, hasChange, err := tx.change(tx.Outputs[index].LockingScript, f, false)
if err != nil {
return err
}
if hasChange {
tx.Outputs[index].Satoshis += available
}
return nil
}

// CalculateFee will return the amount of fees the current transaction will
// require.
func (tx *Tx) CalculateFee(f []*Fee) (uint64, error) {
total := tx.TotalInputSatoshis() - tx.TotalOutputSatoshis()
sats, _, err := tx.change(nil, f, false)
if err != nil {
return 0, err
}
return total - sats, nil
}

// change will return the amount of satoshis to add to an input after fees are removed.
// True will be returned if change has been added.
func (tx *Tx) change(s *bscript.Script, f []*Fee, newOutput bool) (uint64, bool, error) {
inputAmount := tx.TotalInputSatoshis()
outputAmount := tx.TotalOutputSatoshis()

if inputAmount < outputAmount {
return errors.New("satoshis inputted to the tx are less than the outputted satoshis")
return 0, false, errors.New("satoshis inputted to the tx are less than the outputted satoshis")
}

available := inputAmount - outputAmount

standardFees, err := ExtractStandardFee(f)
if err != nil {
return err
return 0, false, err
}

if !tx.canAddChange(available, standardFees) {
return nil
return 0, false, err
}
if newOutput {
tx.AddOutput(&Output{Satoshis: 0, LockingScript: s})
}

tx.AddOutput(&Output{Satoshis: 0, LockingScript: s})

var preSignedFeeRequired uint64
if preSignedFeeRequired, err = tx.getPreSignedFeeRequired(f); err != nil {
return err
return 0, false, err
}

var expectedUnlockingScriptFees uint64
if expectedUnlockingScriptFees, err = tx.getExpectedUnlockingScriptFees(f); err != nil {
return err
return 0, false, err
}

available -= preSignedFeeRequired + expectedUnlockingScriptFees

// add rest of available sats to the change output
tx.Outputs[len(tx.Outputs)-1].Satoshis = available

return nil
return available, true, nil
}

func (tx *Tx) canAddChange(available uint64, standardFees *Fee) bool {
Expand Down
138 changes: 138 additions & 0 deletions txchange_test.go
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
package bt_test

import (
"errors"
"testing"

"github.com/bitcoinsv/bsvutil"
Expand Down Expand Up @@ -299,3 +300,140 @@ func TestTx_Change(t *testing.T) {
assert.Equal(t, "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", tx.ToString())
})
}

func TestTx_ChangeToOutput(t *testing.T) {
tests := map[string]struct {
tx *bt.Tx
index uint
fees []*bt.Fee
expOutputTotal uint64
expChangeOutput uint64
err error
}{
"no change to add should return no change output": {
tx: func() *bt.Tx {
tx := bt.NewTx()
assert.NoError(t, tx.From(
"07912972e42095fe58daaf09161c5a5da57be47c2054dc2aaa52b30fefa1940b",
0,
"76a914af2590a45ae401651fdbdf59a76ad43d1862534088ac",
1000))
assert.NoError(t, tx.PayTo("mxAoAyZFXX6LZBWhoam3vjm6xt9NxPQ15f", 1000))
return tx
}(),
index: 0,
fees: bt.DefaultFees(),
expOutputTotal: 1000,
expChangeOutput: 1000,
err: nil,
}, "change to add should add change to output": {
tx: func() *bt.Tx {
tx := bt.NewTx()
assert.NoError(t, tx.From(
"07912972e42095fe58daaf09161c5a5da57be47c2054dc2aaa52b30fefa1940b",
0,
"76a914af2590a45ae401651fdbdf59a76ad43d1862534088ac",
1000))
assert.NoError(t, tx.PayTo("mxAoAyZFXX6LZBWhoam3vjm6xt9NxPQ15f", 500))
return tx
}(),
index: 0,
fees: bt.DefaultFees(),
expOutputTotal: 904,
expChangeOutput: 904,
err: nil,
}, "change to add should add change to specified output": {
tx: func() *bt.Tx {
tx := bt.NewTx()
assert.NoError(t, tx.From(
"07912972e42095fe58daaf09161c5a5da57be47c2054dc2aaa52b30fefa1940b",
0,
"76a914af2590a45ae401651fdbdf59a76ad43d1862534088ac",
2500))
assert.NoError(t, tx.PayTo("mxAoAyZFXX6LZBWhoam3vjm6xt9NxPQ15f", 500))
assert.NoError(t, tx.PayTo("mxAoAyZFXX6LZBWhoam3vjm6xt9NxPQ15f", 500))
assert.NoError(t, tx.PayTo("mxAoAyZFXX6LZBWhoam3vjm6xt9NxPQ15f", 500))
assert.NoError(t, tx.PayTo("mxAoAyZFXX6LZBWhoam3vjm6xt9NxPQ15f", 500))
return tx
}(),
index: 3,
fees: bt.DefaultFees(),
expOutputTotal: 2353,
expChangeOutput: 853,
err: nil,
}, "index out of range should return error": {
tx: func() *bt.Tx {
tx := bt.NewTx()
assert.NoError(t, tx.From(
"07912972e42095fe58daaf09161c5a5da57be47c2054dc2aaa52b30fefa1940b",
0,
"76a914af2590a45ae401651fdbdf59a76ad43d1862534088ac",
1000))
assert.NoError(t, tx.PayTo("mxAoAyZFXX6LZBWhoam3vjm6xt9NxPQ15f", 500))
return tx
}(),
index: 1,
fees: bt.DefaultFees(),
err: errors.New("index is greater than number of inputs in transaction"),
},
}
for name, test := range tests {
t.Run(name, func(t *testing.T) {
err := test.tx.ChangeToOutput(test.index, test.fees)
if test.err != nil {
assert.Error(t, err)
assert.Equal(t, test.err, err)
return
}
assert.Equal(t, test.expOutputTotal, test.tx.TotalOutputSatoshis())
assert.Equal(t, test.expChangeOutput, test.tx.Outputs[test.index].Satoshis)
})
}
}

func TestTx_CalculateChange(t *testing.T) {
tests := map[string]struct {
tx *bt.Tx
fees []*bt.Fee
expFees uint64
err error
}{
"Transaction with one input one output should return 96": {
tx: func() *bt.Tx {
tx := bt.NewTx()
assert.NoError(t, tx.From(
"07912972e42095fe58daaf09161c5a5da57be47c2054dc2aaa52b30fefa1940b",
0,
"76a914af2590a45ae401651fdbdf59a76ad43d1862534088ac",
1000))
assert.NoError(t, tx.PayTo("mxAoAyZFXX6LZBWhoam3vjm6xt9NxPQ15f", 500))
return tx
}(),
fees: bt.DefaultFees(),
expFees: 96,
}, "Transaction with one input 4 outputs should return 147": {
tx: func() *bt.Tx {
tx := bt.NewTx()
assert.NoError(t, tx.From(
"07912972e42095fe58daaf09161c5a5da57be47c2054dc2aaa52b30fefa1940b",
0,
"76a914af2590a45ae401651fdbdf59a76ad43d1862534088ac",
2500))
assert.NoError(t, tx.PayTo("mxAoAyZFXX6LZBWhoam3vjm6xt9NxPQ15f", 500))
assert.NoError(t, tx.PayTo("mxAoAyZFXX6LZBWhoam3vjm6xt9NxPQ15f", 500))
assert.NoError(t, tx.PayTo("mxAoAyZFXX6LZBWhoam3vjm6xt9NxPQ15f", 500))
assert.NoError(t, tx.PayTo("mxAoAyZFXX6LZBWhoam3vjm6xt9NxPQ15f", 500))
return tx
}(),
fees: bt.DefaultFees(),
expFees: 147,
},
}
for name, test := range tests {
t.Run(name, func(t *testing.T) {
fee, err := test.tx.CalculateFee(test.fees)
assert.Equal(t, test.err, err)
assert.Equal(t, test.expFees, fee)
})
}
}