papyrus_base_layer: sanity check test of data gas price after fusaka upgrade (#10488)

* papyrus_base_layer: fix the fusaka related default config values

* papyrus_base_layer: sanity check test of data gas price after fusaka upgrade

Author: guy-starkware

crates/papyrus_base_layer/src/ethereum_base_layer_contract.rs

@@ -39,6 +39,10 @@ use crate::{
 pub type EthereumBaseLayerResult<T> = Result<T, EthereumBaseLayerError>;
 pub type EthereumContractAddress = Address;
 
+#[cfg(test)]
+#[path = "ethereum_base_layer_contract_test.rs"]
+pub mod ethereum_base_layer_contract_test;
+
 // Wraps the Starknet contract with a type that implements its interface, and is aware of its
 // events.
 

crates/papyrus_base_layer/src/ethereum_base_layer_contract_test.rs

@@ -0,0 +1,82 @@
+use std::time::Duration;
+
+use url::Url;
+
+use crate::ethereum_base_layer_contract::{EthereumBaseLayerConfig, EthereumBaseLayerContract};
+use crate::BaseLayerContract;
+
+#[tokio::test]
+#[ignore = "This test uses external dependencies, like Infura. But still it is a good \
+            reference/sanity check."]
+async fn fusaka_blob_fee_sanity_check() {
+    let config = EthereumBaseLayerConfig {
+        fusaka_no_bpo_start_block_number: 0,
+        bpo1_start_block_number: 0,
+        bpo2_start_block_number: 0,
+        timeout_millis: Duration::from_millis(5000),
+        ..Default::default()
+    };
+
+    // Timeline: Sepolia went on Fusaka on epoch 272640 (slot 8724480) which is about block 9408577
+    // It went on BPO1 on epoch 274176 (slot 8773632) which is about block 9456501
+    // It went on BPO2 on epoch 275712 (slot 8822784) which is about block 9504747
+    let infura_api_key = std::env::var("INFURA_API_KEY")
+        .expect("expected infura api key to be set in INFURA_API_KEY environment variable");
+    let url = Url::parse(&format!("https://sepolia.infura.io/v3/{}", infura_api_key))
+        .expect("expected infura url to be valid");
+    let mut base_layer = EthereumBaseLayerContract::new(config.clone(), url);
+
+    // This is a known time when the data gas price was relatively high:
+    // https://sepolia.blobscan.com/block/9716185
+    // The blob fee here is 0.010629722 wei.
+    let block_number = 9716185;
+    let base_fee_from_blobscan = 10629722;
+    let block_header = base_layer
+        .get_block_header(block_number)
+        .await
+        .expect("expected call to get block header to succeed")
+        .expect("expected block header to be found");
+
+    assert_eq!(block_header.blob_fee, base_fee_from_blobscan);
+
+    // Now try to unset the fusaka configuration, to see if we get a massively bigger blob fee.
+    base_layer.config.fusaka_no_bpo_start_block_number = 100000000;
+    base_layer.config.bpo1_start_block_number = 1000000000;
+    base_layer.config.bpo2_start_block_number = 1000000000;
+    let block_header = base_layer
+        .get_block_header(block_number)
+        .await
+        .expect("expected call to get block header to succeed")
+        .expect("expected block header to be found");
+
+    assert!(block_header.blob_fee > 1000 * base_fee_from_blobscan);
+
+    // Choose a mainnet block number that is not yet on Fusaka (but has non-zero blob fee).
+    // https://blobscan.com/block/23824000
+    // The blob fee here is 31.042082881 Gwei.
+    let url = Url::parse(&format!("https://mainnet.infura.io/v3/{}", infura_api_key))
+        .expect("expected infura url to be valid");
+    let mut base_layer = EthereumBaseLayerContract::new(config, url);
+    base_layer.config.fusaka_no_bpo_start_block_number = 100000000;
+    base_layer.config.bpo1_start_block_number = 1000000000;
+    base_layer.config.bpo2_start_block_number = 1000000000;
+    let block_number = 23824000;
+    let base_fee_from_blobscan = 31042082881;
+    let block_header = base_layer
+        .get_block_header(block_number)
+        .await
+        .expect("expected call to get block header to succeed")
+        .expect("expected block header to be found");
+    assert_eq!(block_header.blob_fee, base_fee_from_blobscan);
+
+    // But if we set the fusaka update to have already happened, we should get a much lower fee.
+    base_layer.config.fusaka_no_bpo_start_block_number = 0;
+    base_layer.config.bpo1_start_block_number = 0;
+    base_layer.config.bpo2_start_block_number = 0;
+    let block_header = base_layer
+        .get_block_header(block_number)
+        .await
+        .expect("expected call to get block header to succeed")
+        .expect("expected block header to be found");
+    assert!(block_header.blob_fee * 1000 < base_fee_from_blobscan);
+}