feat(lazer): Update EVM example to attach fee for verification (#39)

* Add fee but still failing

* Fee correctly used

* Update function stub

* Fix format issue

* Pull fee from lazer contract

Author: darunrs

lazer/evm/lib/forge-std

@@ -14,8 +14,14 @@ contract ExampleReceiver {
         pythLazer = PythLazer(pythLazerAddress);
     }
 
-    function updatePrice(bytes calldata update) public {
-        (bytes memory payload,) = pythLazer.verifyUpdate(update);
+    function updatePrice(bytes calldata update) public payable {
+        uint256 verification_fee = pythLazer.verification_fee();
+        require(msg.value >= verification_fee, "Insufficient fee provided");
+        (bytes memory payload,) = pythLazer.verifyUpdate{value: verification_fee}(update);
+        if (msg.value > verification_fee) {
+            payable(msg.sender).transfer(msg.value - verification_fee);
+        }
+
         (uint64 _timestamp, PythLazerLib.Channel channel, uint8 feedsLen, uint16 pos) =
             PythLazerLib.parsePayloadHeader(payload);
         console.log("timestamp %d", _timestamp);

lazer/evm/lib/openzeppelin-contracts-upgradeable

@@ -12,19 +12,30 @@ contract ExampleReceiverTest is Test {
         address trustedSigner = 0xEfEf56cD66896f6799A90A4e4d512C330c094e44;
         console.log("trustedSigner %s", trustedSigner);
 
+        address lazer = makeAddr("lazer");
         PythLazer pythLazer = new PythLazer();
-        pythLazer.initialize(address(0x1));
-        vm.prank(address(0x1));
+        pythLazer.initialize(lazer);
+
+        vm.prank(lazer);
         pythLazer.updateTrustedSigner(trustedSigner, 3000000000000000);
+        uint256 fee = pythLazer.verification_fee();
 
-        ExampleReceiver receiver = new ExampleReceiver(address(pythLazer));
+        address consumer = makeAddr("consumer");
+        vm.deal(consumer, 10 wei);
 
+        ExampleReceiver receiver = new ExampleReceiver(address(pythLazer));
         bytes memory update =
             hex"2a22999a577d3cc0202197939d736bc0dcf71b9dde7b9470e4d16fa8e2120c0787a1c0d744d0c39cc372af4d1ecf2d09e84160ca905f3f597d20e2eec144a446a0459ad600001c93c7d3750006240af373971c01010000000201000000000005f5e100";
         console.logBytes(update);
 
-        receiver.updatePrice(update);
+        vm.prank(consumer);
+        receiver.updatePrice{value: 5 * fee}(update);
+
         assertEq(receiver.price(), 100000000);
         assertEq(receiver.timestamp(), 1728479312975644);
+
+        assertEq(address(pythLazer).balance, fee);
+        assertEq(address(receiver).balance, 0);
+        assertEq(consumer.balance, 10 wei - fee);
     }
 }