added README for lazer evm example (#65)

Author: nidhi-singh02

lazer/evm/README.md

@@ -1,5 +1,160 @@
-## pyth-lazer-example-evm
+# Pyth Lazer EVM Examples
 
-This package is built using [Foundry](https://book.getfoundry.sh/).
+This directory contains Solidity smart contract examples demonstrating how to integrate Pyth Lazer price feeds into your Ethereum applications using Foundry.
 
-This example contract shows how to use Pyth Lazer SDK to verify signatures and parse payloads from Pyth Lazer.
+## What is Pyth Lazer?
+
+Pyth Lazer is a high-performance, low-latency price feed service that provides real-time financial market data to blockchain applications. It supports multiple blockchain networks and offers both JSON and binary message formats for optimal performance.
+
+## Prerequisites
+
+Before running these examples, make sure you have the following installed:
+
+- **Foundry** - [Installation Guide](https://book.getfoundry.sh/getting-started/installation)
+- Basic understanding of Solidity and smart contracts
+
+## Installation
+
+1. Navigate to the `lazer/evm` directory:
+   ```bash
+   cd lazer/evm
+   ```
+
+2. Install dependencies:
+   ```bash
+   forge install
+   ```
+
+3. Build the contracts:
+   ```bash
+   forge build
+   ```
+
+## Examples
+
+### 1. ExampleReceiver Contract (`src/ExampleReceiver.sol`)
+Demonstrates how to receive and process Pyth Lazer price updates in a smart contract.
+
+**What it does:**
+- Verifies Pyth Lazer signatures on-chain
+- Parses price feed payloads to extract price data
+- Handles verification fees and refunds excess payments
+- Extracts multiple price feed properties (price, timestamps, exponents, etc.)
+- Filters updates by feed ID and timestamp
+
+**Key Functions:**
+```solidity
+function updatePrice(bytes calldata update) public payable
+```
+
+**How to run the test:**
+```bash
+forge test -v
+```
+
+### 2. Test Suite (`test/ExampleReceiver.t.sol`)
+Comprehensive test demonstrating the contract functionality with real price data.
+
+**What it does:**
+- Sets up a PythLazer contract with trusted signer
+- Creates and funds test accounts
+- Submits a price update with verification fee
+- Validates parsed price data and fee handling
+
+**How to run:**
+```bash
+forge test -v
+```
+
+**Expected output:**
+- **Timestamp**: `1738270008001000` (microseconds since Unix epoch)
+- **Price**: `100000000` (raw price value)  
+- **Exponent**: `-8` (price = 100000000 × 10^-8 = $1.00)
+- **Publisher Count**: `1`
+
+## Understanding Price Data
+
+Pyth Lazer prices use a fixed-point representation:
+```
+actual_price = price × 10^exponent
+```
+
+**Example from the test:**
+- Raw price: `100000000`
+- Exponent: `-8`
+- Actual price: `100000000 × 10^-8 = $1.00`
+
+### Feed Properties
+
+The contract can extract multiple price feed properties:
+
+- **Price**: Main price value
+- **BestBidPrice**: Highest bid price in the market
+- **BestAskPrice**: Lowest ask price in the market
+- **Exponent**: Decimal exponent for price normalization
+- **PublisherCount**: Number of publishers contributing to this price
+
+## Integration Guide
+
+To integrate Pyth Lazer into your own contract:
+
+1. **Import the required libraries:**
+   ```solidity
+   import {PythLazer} from "pyth-lazer/PythLazer.sol";
+   import {PythLazerLib} from "pyth-lazer/PythLazerLib.sol";
+   ```
+
+2. **Set up the PythLazer contract:**
+   ```solidity
+   PythLazer pythLazer;
+   constructor(address pythLazerAddress) {
+       pythLazer = PythLazer(pythLazerAddress);
+   }
+   ```
+
+3. **Handle verification fees:**
+   ```solidity
+   uint256 verification_fee = pythLazer.verification_fee();
+   require(msg.value >= verification_fee, "Insufficient fee");
+   ```
+
+4. **Verify and parse updates:**
+   ```solidity
+   (bytes memory payload,) = pythLazer.verifyUpdate{value: verification_fee}(update);
+   // Parse payload using PythLazerLib functions
+   ```
+
+## Configuration
+
+### Feed IDs
+
+The example filters for feed ID `6`. To use different feeds:
+
+1. Update the feed ID check in `updatePrice()`:
+   ```solidity
+   if (feedId == YOUR_FEED_ID && _timestamp > timestamp) {
+       // Update logic
+   }
+   ```
+
+2. Obtain feed IDs from the Pyth Lazer documentation or API
+
+## Troubleshooting
+
+### Common Issues
+
+1. **Build Errors**: Make sure all dependencies are installed with `forge install`
+
+2. **Test Failures**: Ensure you're using a compatible Foundry version and all submodules are properly initialized
+
+3. **Gas Issues**: The contract includes gas optimization for parsing multiple feed properties
+
+## Resources
+
+- [Pyth Network Documentation](https://docs.pyth.network/)
+- [Foundry Book](https://book.getfoundry.sh/)
+- [Pyth Lazer SDK](https://github.com/pyth-network/pyth-crosschain)
+
+## License
+
+This project is licensed under the Apache-2.0 license.

lazer/evm/script/ExampleReceiver.s.sol

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: UNLICENSED
+// SPDX-License-Identifier: Apache-2.0
 pragma solidity ^0.8.13;
 
 import {console} from "forge-std/console.sol";

lazer/evm/src/ExampleReceiver.sol

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: UNLICENSED
+// SPDX-License-Identifier: Apache-2.0
 pragma solidity ^0.8.13;
 
 import {Test, console} from "forge-std/Test.sol";