fix: don't allow self transfer in msg-send

x/ecocredit/base/keeper/msg_send.go

@@ -16,11 +16,16 @@ import (
 
 // Send sends credits to a recipient.
 // Send also retires credits if the amount to retire is specified in the request.
+// NOTE: This method will return an error if both sender and recipient are same.
 func (k Keeper) Send(ctx context.Context, req *types.MsgSend) (*types.MsgSendResponse, error) {
 	sdkCtx := sdk.UnwrapSDKContext(ctx)
 	sender, _ := sdk.AccAddressFromBech32(req.Sender)
 	recipient, _ := sdk.AccAddressFromBech32(req.Recipient)
 
+	if sender.Equals(recipient) {
+		return nil, sdkerrors.ErrInvalidRequest.Wrap("sender and recipient cannot be the same")
+	}
+
 	for _, credit := range req.Credits {
 		err := k.sendEcocredits(sdkCtx, credit, recipient, sender)
 		if err != nil {

x/ecocredit/base/types/v1/features/msg_send.feature

@@ -283,3 +283,23 @@ Feature: MsgSend
       }
     }
     """
+
+  Scenario: an error is returned if sender and recipient are the same
+    Given the message
+    """
+    {
+      "sender":"regen1depk54cuajgkzea6zpgkq36tnjwdzv4ak663u6",
+      "recipient":"regen1depk54cuajgkzea6zpgkq36tnjwdzv4ak663u6",
+      "credits": [
+        {
+          "batch_denom": "C01-001-20200101-20210101-001",
+          "tradable_amount": "100",
+          "retired_amount": "100",
+          "retirement_jurisdiction": "US-WA",
+          "retirement_reason": "offsetting electricity consumption"
+        }
+      ]
+    }
+    """
+    When the message is validated
+    Then expect the error "sender and recipient cannot be the same: invalid request"

x/ecocredit/base/types/v1/msg_send.go

@@ -37,6 +37,10 @@ func (m *MsgSend) ValidateBasic() error {
 		return sdkerrors.ErrInvalidAddress.Wrapf("recipient: %s", err)
 	}
 
+	if m.Sender == m.Recipient {
+		return sdkerrors.ErrInvalidRequest.Wrap("sender and recipient cannot be the same")
+	}
+
 	if len(m.Credits) == 0 {
 		return sdkerrors.ErrInvalidRequest.Wrap("credits cannot be empty")
 	}