fix: allow empty accounts in solana additional fields for transactions (#324)

This pull request includes changes to the Solana SDK to allow empty
accounts in the additional fields for transactions. The changes allow
solana transactions to include empty account slices or `nil` account
slices.

### Validation updates:

*
[`sdk/solana/transaction.go`](diffhunk://#diff-818b97cb2182dd9070d9b993ec0a302ce1b35ca68828dd0013efb2523dd67567L20-R20):
Modified the `AdditionalFields` struct to make the `Accounts` field
optional by changing the validation tag from `required` to `omitempty`.
Also updated the error message in `ValidateAdditionalFields` to
correctly reference Solana instead of EVM.
[[1]](diffhunk://#diff-818b97cb2182dd9070d9b993ec0a302ce1b35ca68828dd0013efb2523dd67567L20-R20)
[[2]](diffhunk://#diff-818b97cb2182dd9070d9b993ec0a302ce1b35ca68828dd0013efb2523dd67567L32-R32)

### Test additions:

*
[`sdk/solana/transaction_test.go`](diffhunk://#diff-31bead2377fc131bd4de0aad5e09a1f88d4e5219ac05024bb3be8903af83e8e1R4-R5):
Added import statements for `encoding/json` and `math/big`.
*
[`sdk/solana/transaction_test.go`](diffhunk://#diff-31bead2377fc131bd4de0aad5e09a1f88d4e5219ac05024bb3be8903af83e8e1R64-R172):
Added `TestValidateAdditionalFields` to test various scenarios for the
`ValidateAdditionalFields` function, including valid fields, missing
accounts, empty accounts, malformed JSON, and empty input.
*
[`sdk/solana/transaction_test.go`](diffhunk://#diff-31bead2377fc131bd4de0aad5e09a1f88d4e5219ac05024bb3be8903af83e8e1R64-R172):
Added `TestAdditionalFieldsValidate` to test the `Validate` method of
the `AdditionalFields` struct with different account configurations.

### Documentation:

*
[`.changeset/silver-beans-design.md`](diffhunk://#diff-9774278eb988dd2dfd819b6b73aa54cc8c79ac5a8054349aaa9891f3bdf75b24R1-R5):
Added a changeset to document the patch for allowing empty accounts in
Solana additional fields for transactions.

Author: ecPablo

.changeset/silver-beans-design.md

@@ -0,0 +1,5 @@
+---
+"@smartcontractkit/mcms": patch
+---
+
+allow empty accounts in solana additional fields for transactions

sdk/solana/transaction.go

@@ -17,7 +17,7 @@ func ValidateAdditionalFields(additionalFields json.RawMessage) error {
 	}
 	if len(additionalFields) != 0 {
 		if err := json.Unmarshal(additionalFields, &fields); err != nil {
-			return fmt.Errorf("failed to unmarshal EVM additional fields: %w", err)
+			return fmt.Errorf("failed to unmarshal solana additional fields: %w", err)
 		}
 	}
 
@@ -29,7 +29,7 @@ func ValidateAdditionalFields(additionalFields json.RawMessage) error {
 }
 
 type AdditionalFields struct {
-	Accounts []*solana.AccountMeta `json:"accounts" validate:"required"`
+	Accounts []*solana.AccountMeta `json:"accounts" validate:"omitempty"`
 	Value    *big.Int              `json:"value" validate:"omitempty"`
 }
 

sdk/solana/transaction_test.go

@@ -1,6 +1,8 @@
 package solana
 
 import (
+	"encoding/json"
+	"math/big"
 	"testing"
 
 	"github.com/gagliardetto/solana-go"
@@ -59,3 +61,121 @@ func TestNewTransactionFromInstruction(t *testing.T) {
 		})
 	}
 }
+
+func TestValidateAdditionalFields(t *testing.T) {
+	t.Parallel()
+
+	validAccount := &solana.AccountMeta{
+		PublicKey: solana.MustPublicKeyFromBase58("11111111111111111111111111111111"),
+		IsSigner:  true,
+	}
+	tests := []struct {
+		name        string
+		input       json.RawMessage
+		wantErr     bool
+		errContains string
+	}{
+		{
+			name: "valid fields",
+			input: func() json.RawMessage {
+				fields := AdditionalFields{
+					Accounts: []*solana.AccountMeta{validAccount},
+					Value:    big.NewInt(100),
+				}
+				data, err := json.Marshal(fields)
+				require.NoError(t, err)
+
+				return data
+			}(),
+			wantErr: false,
+		},
+		{
+			name:    "missing accounts field",
+			input:   []byte(`{"value": 100}`),
+			wantErr: false,
+		},
+		{
+			name:    "empty accounts slice",
+			input:   []byte(`{"accounts": [], "value": 100}`),
+			wantErr: false,
+		},
+		{
+			name:        "malformed json",
+			input:       []byte(`invalid json`),
+			wantErr:     true,
+			errContains: "failed to unmarshal",
+		},
+		{
+			name:  "empty input",
+			input: []byte(""),
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			err := ValidateAdditionalFields(tc.input)
+			if tc.wantErr {
+				require.Error(t, err)
+				require.Contains(t, err.Error(), tc.errContains)
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
+}
+
+func TestAdditionalFieldsValidate(t *testing.T) {
+	t.Parallel()
+
+	validAccount := &solana.AccountMeta{
+		PublicKey: solana.MustPublicKeyFromBase58("11111111111111111111111111111111"),
+		IsSigner:  true,
+	}
+	tests := []struct {
+		name        string
+		fields      AdditionalFields
+		wantErr     bool
+		errContains string
+	}{
+		{
+			name: "valid additional fields",
+			fields: AdditionalFields{
+				Accounts: []*solana.AccountMeta{validAccount},
+				Value:    big.NewInt(123),
+			},
+			wantErr: false,
+		},
+		{
+			name: "nil accounts",
+			fields: AdditionalFields{
+				Accounts: nil,
+				Value:    big.NewInt(123),
+			},
+			wantErr: false,
+		},
+		{
+			name: "empty accounts",
+			fields: AdditionalFields{
+				Accounts: []*solana.AccountMeta{},
+				Value:    big.NewInt(123),
+			},
+			wantErr: false,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			err := tc.fields.Validate()
+			if tc.wantErr {
+				require.Error(t, err)
+				require.Contains(t, err.Error(), tc.errContains)
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
+}