Add README.md in external_program_for_testing

Author: zpoken

solana/Anchor.toml

@@ -8,7 +8,6 @@ members = ["programs/staking"]
 
 [programs.localnet]
 staking = "DgCSKsLDXXufYeEkvf21YSX5DMnFK89xans5WdSsUbeY"
-external_program = "eLUV8cwhgUC2Bcu4UA16uhuMwK8zPkx3XSzt4hd3JJ3"
 
 [programs.devnet]
 staking = "DgCSKsLDXXufYeEkvf21YSX5DMnFK89xans5WdSsUbeY"

solana/programs/external_program/Cargo.lock solana/programs/external_program_for_testing/Cargo.lock

@@ -0,0 +1,26 @@
+# External Program for EVM-Solana E2E Testing
+
+This folder contains a simple Anchor-based Solana program used exclusively for end-to-end (E2E) testing in the development environment. 
+
+The purpose of this program is to verify the proper execution of the `ReceiveMessage` instruction in the Solana devnet. By doing so, this program helps validate the delivery of cross-chain messages from EVM to Solana.
+
+## Program Details
+The program consists of the following key elements:
+- **Initialize Instruction**: Sets up a configuration account with an admin address and initializes a counter to `0`.
+- **AdminAction Instruction**: Increments the counter only if the provided admin address matches the stored admin address.
+
+### Purpose of the Counter
+The counter is used to ensure that the `AdminAction` instruction executes successfully in the Solana devnet. Each successful call increments the counter, which is logged for verification.
+
+## How to Use
+1. Deploy the program to Solana devnet.
+2. Use the accompanying E2E test scripts to interact with this program.
+3. Verify that the instruction executes properly by observing the counter value in the logs.
+
+## Testing Flow
+1. **Generate Payload**: The script generates a Solana instruction payload using this external program.
+2. **Dispatch Payload**: The payload is dispatched to Solana via the EVM contract (`HubSolanaMessageDispatcher`).
+3. **Verify Execution**: Check the success of the instruction by checking the increment of the counter.
+
+## Note
+This program is intended **only for testing purposes** in the devnet and should not be used in production.