From fc925a99d7a8a59d1c8bcad7c664687161b967cc Mon Sep 17 00:00:00 2001 From: Marius van der Wijden Date: Tue, 21 Apr 2020 12:38:16 +0200 Subject: [PATCH] accounts/abi: added tuple test cases --- accounts/abi/pack_test.go | 3 +- accounts/abi/packing_test.go | 323 +++++++++++++++++------------------ accounts/abi/unpack_test.go | 85 +++++---- 3 files changed, 209 insertions(+), 202 deletions(-) diff --git a/accounts/abi/pack_test.go b/accounts/abi/pack_test.go index dea83a3dc0..284215a7d7 100644 --- a/accounts/abi/pack_test.go +++ b/accounts/abi/pack_test.go @@ -30,7 +30,8 @@ import ( "github.com/ethereum/go-ethereum/common" ) -func TestPack_Pack(t *testing.T) { +// TestPack tests the general pack/unpack tests in packing_test.go +func TestPack(t *testing.T) { for i, test := range packUnpackTests { t.Run(strconv.Itoa(i), func(t *testing.T) { encb, err := hex.DecodeString(test.packed) diff --git a/accounts/abi/packing_test.go b/accounts/abi/packing_test.go index be20373e21..2bbad54338 100644 --- a/accounts/abi/packing_test.go +++ b/accounts/abi/packing_test.go @@ -819,7 +819,6 @@ var packUnpackTests = []packUnpackTest{ "0400000000000000000000000000000000000000000000000000000000000000" + // array[1][1] "0500000000000000000000000000000000000000000000000000000000000000", // array[1][2] }, - { def: `[{"type": "bytes32[3][2]"}]`, unpacked: [2][3][32]byte{{{1}, {2}, {3}}, {{3}, {4}, {5}}}, @@ -830,178 +829,160 @@ var packUnpackTests = []packUnpackTest{ "0400000000000000000000000000000000000000000000000000000000000000" + // array[1][1] "0500000000000000000000000000000000000000000000000000000000000000", // array[1][2] }, + { + // static tuple + def: `[{"name":"a","type":"int64"}, + {"name":"b","type":"int256"}, + {"name":"c","type":"int256"}, + {"name":"d","type":"bool"}, + {"name":"e","type":"bytes32[3][2]"}]`, + unpacked: struct { + A int64 + B *big.Int + C *big.Int + D bool + E [2][3][32]byte + }{1, big.NewInt(1), big.NewInt(-1), true, [2][3][32]byte{{{1}, {2}, {3}}, {{3}, {4}, {5}}}}, + packed: "0000000000000000000000000000000000000000000000000000000000000001" + // struct[a] + "0000000000000000000000000000000000000000000000000000000000000001" + // struct[b] + "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" + // struct[c] + "0000000000000000000000000000000000000000000000000000000000000001" + // struct[d] + "0100000000000000000000000000000000000000000000000000000000000000" + // struct[e] array[0][0] + "0200000000000000000000000000000000000000000000000000000000000000" + // struct[e] array[0][1] + "0300000000000000000000000000000000000000000000000000000000000000" + // struct[e] array[0][2] + "0300000000000000000000000000000000000000000000000000000000000000" + // struct[e] array[1][0] + "0400000000000000000000000000000000000000000000000000000000000000" + // struct[e] array[1][1] + "0500000000000000000000000000000000000000000000000000000000000000", // struct[e] array[1][2] + }, + { + def: `[{"name":"a","type":"string"}, + {"name":"b","type":"int64"}, + {"name":"c","type":"bytes"}, + {"name":"d","type":"string[]"}, + {"name":"e","type":"int256[]"}, + {"name":"f","type":"address[]"}]`, + unpacked: struct { + FieldA string `abi:"a"` // Test whether abi tag works + FieldB int64 `abi:"b"` + C []byte + D []string + E []*big.Int + F []common.Address + }{"foobar", 1, []byte{1}, []string{"foo", "bar"}, []*big.Int{big.NewInt(1), big.NewInt(-1)}, []common.Address{{1}, {2}}}, + packed: "00000000000000000000000000000000000000000000000000000000000000c0" + // struct[a] offset + "0000000000000000000000000000000000000000000000000000000000000001" + // struct[b] + "0000000000000000000000000000000000000000000000000000000000000100" + // struct[c] offset + "0000000000000000000000000000000000000000000000000000000000000140" + // struct[d] offset + "0000000000000000000000000000000000000000000000000000000000000220" + // struct[e] offset + "0000000000000000000000000000000000000000000000000000000000000280" + // struct[f] offset + "0000000000000000000000000000000000000000000000000000000000000006" + // struct[a] length + "666f6f6261720000000000000000000000000000000000000000000000000000" + // struct[a] "foobar" + "0000000000000000000000000000000000000000000000000000000000000001" + // struct[c] length + "0100000000000000000000000000000000000000000000000000000000000000" + // []byte{1} + "0000000000000000000000000000000000000000000000000000000000000002" + // struct[d] length + "0000000000000000000000000000000000000000000000000000000000000040" + // foo offset + "0000000000000000000000000000000000000000000000000000000000000080" + // bar offset + "0000000000000000000000000000000000000000000000000000000000000003" + // foo length + "666f6f0000000000000000000000000000000000000000000000000000000000" + // foo + "0000000000000000000000000000000000000000000000000000000000000003" + // bar offset + "6261720000000000000000000000000000000000000000000000000000000000" + // bar + "0000000000000000000000000000000000000000000000000000000000000002" + // struct[e] length + "0000000000000000000000000000000000000000000000000000000000000001" + // 1 + "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" + // -1 + "0000000000000000000000000000000000000000000000000000000000000002" + // struct[f] length + "0000000000000000000000000100000000000000000000000000000000000000" + // common.Address{1} + "0000000000000000000000000200000000000000000000000000000000000000", // common.Address{2} + }, + { + def: `[{"components": [{"name": "a","type": "uint256"}, + {"name": "b","type": "uint256[]"}], + "name": "a","type": "tuple"}, + {"name": "b","type": "uint256[]"}]`, + unpacked: struct { + A struct { + FieldA *big.Int `abi:"a"` + B []*big.Int + } + B []*big.Int + }{ + A: struct { + FieldA *big.Int `abi:"a"` // Test whether abi tag works for nested tuple + B []*big.Int + }{big.NewInt(1), []*big.Int{big.NewInt(1), big.NewInt(2)}}, + B: []*big.Int{big.NewInt(1), big.NewInt(2)}}, + packed: "0000000000000000000000000000000000000000000000000000000000000040" + // a offset + "00000000000000000000000000000000000000000000000000000000000000e0" + // b offset + "0000000000000000000000000000000000000000000000000000000000000001" + // a.a value + "0000000000000000000000000000000000000000000000000000000000000040" + // a.b offset + "0000000000000000000000000000000000000000000000000000000000000002" + // a.b length + "0000000000000000000000000000000000000000000000000000000000000001" + // a.b[0] value + "0000000000000000000000000000000000000000000000000000000000000002" + // a.b[1] value + "0000000000000000000000000000000000000000000000000000000000000002" + // b length + "0000000000000000000000000000000000000000000000000000000000000001" + // b[0] value + "0000000000000000000000000000000000000000000000000000000000000002", // b[1] value + }, - /* - { - // static tuple - "tuple", - []ArgumentMarshaling{ - {Name: "a", Type: "int64"}, - {Name: "b", Type: "int256"}, - {Name: "c", Type: "int256"}, - {Name: "d", Type: "bool"}, - {Name: "e", Type: "bytes32[3][2]"}, - }, - struct { - A int64 - B *big.Int - C *big.Int - D bool - E [][]common.Hash - }{1, big.NewInt(1), big.NewInt(-1), true, [][]common.Hash{{{1}, {2}, {3}}, {{3}, {4}, {5}}}}, - packed: "0000000000000000000000000000000000000000000000000000000000000001" + // struct[a] - "0000000000000000000000000000000000000000000000000000000000000001" + // struct[b] - "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" + // struct[c] - "0000000000000000000000000000000000000000000000000000000000000001" + // struct[d] - "0100000000000000000000000000000000000000000000000000000000000000" + // struct[e] array[0][0] - "0200000000000000000000000000000000000000000000000000000000000000" + // struct[e] array[0][1] - "0300000000000000000000000000000000000000000000000000000000000000" + // struct[e] array[0][2] - "0300000000000000000000000000000000000000000000000000000000000000" + // struct[e] array[1][0] - "0400000000000000000000000000000000000000000000000000000000000000" + // struct[e] array[1][1] - "0500000000000000000000000000000000000000000000000000000000000000", // struct[e] array[1][2] + { + def: `[{"components": [{"name": "a","type": "int256"}, + {"name": "b","type": "int256[]"}], + "name": "a","type": "tuple[]"}]`, + unpacked: []struct { + A *big.Int + B []*big.Int + }{ + {big.NewInt(-1), []*big.Int{big.NewInt(1), big.NewInt(3)}}, + {big.NewInt(1), []*big.Int{big.NewInt(2), big.NewInt(-1)}}, }, - { - // dynamic tuple - "tuple", - []ArgumentMarshaling{ - {Name: "a", Type: "string"}, - {Name: "b", Type: "int64"}, - {Name: "c", Type: "bytes"}, - {Name: "d", Type: "string[]"}, - {Name: "e", Type: "int256[]"}, - {Name: "f", Type: "address[]"}, - }, - struct { - FieldA string `abi:"a"` // Test whether abi tag works - FieldB int64 `abi:"b"` - C []byte - D []string - E []*big.Int - F []common.Address - }{"foobar", 1, []byte{1}, []string{"foo", "bar"}, []*big.Int{big.NewInt(1), big.NewInt(-1)}, []common.Address{{1}, {2}}}, - packed: "00000000000000000000000000000000000000000000000000000000000000c0" + // struct[a] offset - "0000000000000000000000000000000000000000000000000000000000000001" + // struct[b] - "0000000000000000000000000000000000000000000000000000000000000100" + // struct[c] offset - "0000000000000000000000000000000000000000000000000000000000000140" + // struct[d] offset - "0000000000000000000000000000000000000000000000000000000000000220" + // struct[e] offset - "0000000000000000000000000000000000000000000000000000000000000280" + // struct[f] offset - "0000000000000000000000000000000000000000000000000000000000000006" + // struct[a] length - "666f6f6261720000000000000000000000000000000000000000000000000000" + // struct[a] "foobar" - "0000000000000000000000000000000000000000000000000000000000000001" + // struct[c] length - "0100000000000000000000000000000000000000000000000000000000000000" + // []byte{1} - "0000000000000000000000000000000000000000000000000000000000000002" + // struct[d] length - "0000000000000000000000000000000000000000000000000000000000000040" + // foo offset - "0000000000000000000000000000000000000000000000000000000000000080" + // bar offset - "0000000000000000000000000000000000000000000000000000000000000003" + // foo length - "666f6f0000000000000000000000000000000000000000000000000000000000" + // foo - "0000000000000000000000000000000000000000000000000000000000000003" + // bar offset - "6261720000000000000000000000000000000000000000000000000000000000" + // bar - "0000000000000000000000000000000000000000000000000000000000000002" + // struct[e] length - "0000000000000000000000000000000000000000000000000000000000000001" + // 1 - "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" + // -1 - "0000000000000000000000000000000000000000000000000000000000000002" + // struct[f] length - "0000000000000000000000000100000000000000000000000000000000000000" + // common.Address{1} - "0000000000000000000000000200000000000000000000000000000000000000", // common.Address{2} + packed: "0000000000000000000000000000000000000000000000000000000000000020" + + "0000000000000000000000000000000000000000000000000000000000000002" + // tuple length + "0000000000000000000000000000000000000000000000000000000000000040" + // tuple[0] offset + "00000000000000000000000000000000000000000000000000000000000000e0" + // tuple[1] offset + "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" + // tuple[0].A + "0000000000000000000000000000000000000000000000000000000000000040" + // tuple[0].B offset + "0000000000000000000000000000000000000000000000000000000000000002" + // tuple[0].B length + "0000000000000000000000000000000000000000000000000000000000000001" + // tuple[0].B[0] value + "0000000000000000000000000000000000000000000000000000000000000003" + // tuple[0].B[1] value + "0000000000000000000000000000000000000000000000000000000000000001" + // tuple[1].A + "0000000000000000000000000000000000000000000000000000000000000040" + // tuple[1].B offset + "0000000000000000000000000000000000000000000000000000000000000002" + // tuple[1].B length + "0000000000000000000000000000000000000000000000000000000000000002" + // tuple[1].B[0] value + "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", // tuple[1].B[1] value + }, + { + def: `[{"components": [{"name": "a","type": "int256"}, + {"name": "b","type": "int256"}], + "name": "a","type": "tuple[2]"}]`, + unpacked: [2]struct { + A *big.Int + B *big.Int + }{ + {big.NewInt(-1), big.NewInt(1)}, + {big.NewInt(1), big.NewInt(-1)}, }, - { - // nested tuple - "tuple", - []ArgumentMarshaling{ - {Name: "a", Type: "tuple", Components: []ArgumentMarshaling{{Name: "a", Type: "uint256"}, {Name: "b", Type: "uint256[]"}}}, - {Name: "b", Type: "int256[]"}, - }, - struct { - A struct { - FieldA *big.Int `abi:"a"` - B []*big.Int - } - B []*big.Int - }{ - A: struct { - FieldA *big.Int `abi:"a"` // Test whether abi tag works for nested tuple - B []*big.Int - }{big.NewInt(1), []*big.Int{big.NewInt(1), big.NewInt(0)}}, - B: []*big.Int{big.NewInt(1), big.NewInt(0)}}, - packed: "0000000000000000000000000000000000000000000000000000000000000040" + // a offset - "00000000000000000000000000000000000000000000000000000000000000e0" + // b offset - "0000000000000000000000000000000000000000000000000000000000000001" + // a.a value - "0000000000000000000000000000000000000000000000000000000000000040" + // a.b offset - "0000000000000000000000000000000000000000000000000000000000000002" + // a.b length - "0000000000000000000000000000000000000000000000000000000000000001" + // a.b[0] value - "0000000000000000000000000000000000000000000000000000000000000000" + // a.b[1] value - "0000000000000000000000000000000000000000000000000000000000000002" + // b length - "0000000000000000000000000000000000000000000000000000000000000001" + // b[0] value - "0000000000000000000000000000000000000000000000000000000000000000", // b[1] value + packed: "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" + // tuple[0].a + "0000000000000000000000000000000000000000000000000000000000000001" + // tuple[0].b + "0000000000000000000000000000000000000000000000000000000000000001" + // tuple[1].a + "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", // tuple[1].b + }, + { + def: `[{"components": [{"name": "a","type": "int256[]"}], + "name": "a","type": "tuple[2]"}]`, + unpacked: [2]struct { + A []*big.Int + }{ + {[]*big.Int{big.NewInt(-1), big.NewInt(1)}}, + {[]*big.Int{big.NewInt(1), big.NewInt(-1)}}, }, - { - // tuple slice - "tuple[]", - []ArgumentMarshaling{ - {Name: "a", Type: "int256"}, - {Name: "b", Type: "int256[]"}, - }, - []struct { - A *big.Int - B []*big.Int - }{ - {big.NewInt(-1), []*big.Int{big.NewInt(1), big.NewInt(0)}}, - {big.NewInt(1), []*big.Int{big.NewInt(2), big.NewInt(-1)}}, - }, - packed: "0000000000000000000000000000000000000000000000000000000000000002" + // tuple length - "0000000000000000000000000000000000000000000000000000000000000040" + // tuple[0] offset - "00000000000000000000000000000000000000000000000000000000000000e0" + // tuple[1] offset - "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" + // tuple[0].A - "0000000000000000000000000000000000000000000000000000000000000040" + // tuple[0].B offset - "0000000000000000000000000000000000000000000000000000000000000002" + // tuple[0].B length - "0000000000000000000000000000000000000000000000000000000000000001" + // tuple[0].B[0] value - "0000000000000000000000000000000000000000000000000000000000000000" + // tuple[0].B[1] value - "0000000000000000000000000000000000000000000000000000000000000001" + // tuple[1].A - "0000000000000000000000000000000000000000000000000000000000000040" + // tuple[1].B offset - "0000000000000000000000000000000000000000000000000000000000000002" + // tuple[1].B length - "0000000000000000000000000000000000000000000000000000000000000002" + // tuple[1].B[0] value - "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", // tuple[1].B[1] value - }, - { - // static tuple array - "tuple[2]", - []ArgumentMarshaling{ - {Name: "a", Type: "int256"}, - {Name: "b", Type: "int256"}, - }, - [2]struct { - A *big.Int - B *big.Int - }{ - {big.NewInt(-1), big.NewInt(1)}, - {big.NewInt(1), big.NewInt(-1)}, - }, - packed: "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" + // tuple[0].a - "0000000000000000000000000000000000000000000000000000000000000001" + // tuple[0].b - "0000000000000000000000000000000000000000000000000000000000000001" + // tuple[1].a - "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", // tuple[1].b - }, - { - // dynamic tuple array - "tuple[2]", - []ArgumentMarshaling{ - {Name: "a", Type: "int256[]"}, - }, - [2]struct { - A []*big.Int - }{ - {[]*big.Int{big.NewInt(-1), big.NewInt(1)}}, - {[]*big.Int{big.NewInt(1), big.NewInt(-1)}}, - }, - packed: "0000000000000000000000000000000000000000000000000000000000000040" + // tuple[0] offset - "00000000000000000000000000000000000000000000000000000000000000c0" + // tuple[1] offset - "0000000000000000000000000000000000000000000000000000000000000020" + // tuple[0].A offset - "0000000000000000000000000000000000000000000000000000000000000002" + // tuple[0].A length - "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" + // tuple[0].A[0] - "0000000000000000000000000000000000000000000000000000000000000001" + // tuple[0].A[1] - "0000000000000000000000000000000000000000000000000000000000000020" + // tuple[1].A offset - "0000000000000000000000000000000000000000000000000000000000000002" + // tuple[1].A length - "0000000000000000000000000000000000000000000000000000000000000001" + // tuple[1].A[0] - "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", // tuple[1].A[1] - }, - */ + packed: "0000000000000000000000000000000000000000000000000000000000000020" + + "0000000000000000000000000000000000000000000000000000000000000040" + // tuple[0] offset + "00000000000000000000000000000000000000000000000000000000000000c0" + // tuple[1] offset + "0000000000000000000000000000000000000000000000000000000000000020" + // tuple[0].A offset + "0000000000000000000000000000000000000000000000000000000000000002" + // tuple[0].A length + "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" + // tuple[0].A[0] + "0000000000000000000000000000000000000000000000000000000000000001" + // tuple[0].A[1] + "0000000000000000000000000000000000000000000000000000000000000020" + // tuple[1].A offset + "0000000000000000000000000000000000000000000000000000000000000002" + // tuple[1].A length + "0000000000000000000000000000000000000000000000000000000000000001" + // tuple[1].A[0] + "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", // tuple[1].A[1] + }, } diff --git a/accounts/abi/unpack_test.go b/accounts/abi/unpack_test.go index cd47a2f964..97a2723080 100644 --- a/accounts/abi/unpack_test.go +++ b/accounts/abi/unpack_test.go @@ -30,6 +30,34 @@ import ( "github.com/stretchr/testify/require" ) +// TestUnpack tests the general pack/unpack tests in packing_test.go +func TestUnpack(t *testing.T) { + for i, test := range packUnpackTests { + t.Run(strconv.Itoa(i), func(t *testing.T) { + //Unpack + def := fmt.Sprintf(`[{ "name" : "method", "type": "function", "outputs": %s}]`, test.def) + abi, err := JSON(strings.NewReader(def)) + if err != nil { + t.Fatalf("invalid ABI definition %s: %v", def, err) + } + encb, err := hex.DecodeString(test.packed) + if err != nil { + t.Fatalf("invalid hex %s: %v", test.packed, err) + } + outptr := reflect.New(reflect.TypeOf(test.unpacked)) + err = abi.Unpack(outptr.Interface(), "method", encb) + if err != nil { + t.Errorf("test %d (%v) failed: %v", i, test.def, err) + return + } + out := outptr.Elem().Interface() + if !reflect.DeepEqual(test.unpacked, out) { + t.Errorf("test %d (%v) failed: expected %v, got %v", i, test.def, test.unpacked, out) + } + }) + } +} + type unpackTest struct { def string // ABI definition JSON enc string // evm return data @@ -50,7 +78,7 @@ func (test unpackTest) checkError(err error) error { return nil } -var unpackFailTests = []unpackTest{ +var unpackTests = []unpackTest{ // Bools { def: `[{ "type": "bool" }]`, @@ -155,10 +183,34 @@ var unpackFailTests = []unpackTest{ }{}, err: "abi: purely underscored output cannot unpack to struct", }, + // Make sure only the first argument is consumed + { + def: `[{"name":"int_one","type":"int256"}]`, + enc: "00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002", + want: struct { + IntOne *big.Int + }{big.NewInt(1)}, + }, + { + def: `[{"name":"int__one","type":"int256"}]`, + enc: "00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002", + want: struct { + IntOne *big.Int + }{big.NewInt(1)}, + }, + { + def: `[{"name":"int_one_","type":"int256"}]`, + enc: "00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002", + want: struct { + IntOne *big.Int + }{big.NewInt(1)}, + }, } -func TestUnpackFails(t *testing.T) { - for i, test := range unpackFailTests { +// TestLocalUnpackTests runs test specially designed only for unpacking. +// All test cases that can be used to test packing and unpacking should move to packing_test.go +func TestLocalUnpackTests(t *testing.T) { + for i, test := range unpackTests { t.Run(strconv.Itoa(i), func(t *testing.T) { //Unpack def := fmt.Sprintf(`[{ "name" : "method", "type": "function", "outputs": %s}]`, test.def) @@ -184,33 +236,6 @@ func TestUnpackFails(t *testing.T) { } } -func TestUnpack(t *testing.T) { - for i, test := range packUnpackTests { - t.Run(strconv.Itoa(i), func(t *testing.T) { - //Unpack - def := fmt.Sprintf(`[{ "name" : "method", "type": "function", "outputs": %s}]`, test.def) - abi, err := JSON(strings.NewReader(def)) - if err != nil { - t.Fatalf("invalid ABI definition %s: %v", def, err) - } - encb, err := hex.DecodeString(test.packed) - if err != nil { - t.Fatalf("invalid hex %s: %v", test.packed, err) - } - outptr := reflect.New(reflect.TypeOf(test.unpacked)) - err = abi.Unpack(outptr.Interface(), "method", encb) - if err != nil { - t.Errorf("test %d (%v) failed: %v", i, test.def, err) - return - } - out := outptr.Elem().Interface() - if !reflect.DeepEqual(test.unpacked, out) { - t.Errorf("test %d (%v) failed: expected %v, got %v", i, test.def, test.unpacked, out) - } - }) - } -} - func TestUnpackSetDynamicArrayOutput(t *testing.T) { abi, err := JSON(strings.NewReader(`[{"constant":true,"inputs":[],"name":"testDynamicFixedBytes15","outputs":[{"name":"","type":"bytes15[]"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"testDynamicFixedBytes32","outputs":[{"name":"","type":"bytes32[]"}],"payable":false,"stateMutability":"view","type":"function"}]`)) if err != nil {