Fix http api tests ci (#7943)

Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>

Co-Authored-By: Michael Sproul <micsproul@gmail.com>

Co-Authored-By: Michael Sproul <michael@sigmaprime.io>

Co-Authored-By: hopinheimer <knmanas6@gmail.com>

beacon_node/http_api/src/test_utils.rs

@@ -60,8 +60,15 @@ type Mutator<E> = BoxedMutator<E, MemoryStore<E>, MemoryStore<E>>;
 
 impl<E: EthSpec> InteractiveTester<E> {
     pub async fn new(spec: Option<ChainSpec>, validator_count: usize) -> Self {
-        Self::new_with_initializer_and_mutator(spec, validator_count, None, None, Config::default())
-            .await
+        Self::new_with_initializer_and_mutator(
+            spec,
+            validator_count,
+            None,
+            None,
+            Config::default(),
+            true,
+        )
+        .await
     }
 
     pub async fn new_with_initializer_and_mutator(
@@ -70,6 +77,7 @@ impl<E: EthSpec> InteractiveTester<E> {
         initializer: Option<Initializer<E>>,
         mutator: Option<Mutator<E>>,
         config: Config,
+        use_mock_builder: bool,
     ) -> Self {
         let mut harness_builder = BeaconChainHarness::builder(E::default())
             .spec_or_default(spec.map(Arc::new))
@@ -91,7 +99,7 @@ impl<E: EthSpec> InteractiveTester<E> {
             harness_builder = harness_builder.initial_mutator(mutator);
         }
 
-        let harness = harness_builder.build();
+        let mut harness = harness_builder.build();
 
         let ApiServer {
             ctx,
@@ -103,6 +111,40 @@ impl<E: EthSpec> InteractiveTester<E> {
 
         tokio::spawn(server);
 
+        // Late-initalize the mock builder now that the mock execution node and beacon API ports
+        // have been allocated.
+        let beacon_api_ip = listening_socket.ip();
+        let beacon_api_port = listening_socket.port();
+        let beacon_url =
+            SensitiveUrl::parse(format!("http://{beacon_api_ip}:{beacon_api_port}").as_str())
+                .unwrap();
+
+        // We disable apply_operations because it breaks the mock builder's ability to return
+        // payloads.
+        let apply_operations = false;
+
+        // We disable strict registration checks too, because it makes HTTP tests less fiddly to
+        // write.
+        let strict_registrations = false;
+
+        // Broadcast to the BN only if Fulu is scheduled. In the broadcast validation tests we want
+        // to infer things from the builder return code, and pre-Fulu it's simpler to let the BN
+        // handle broadcast and return detailed codes. Post-Fulu the builder doesn't return the
+        // block at all, so we *need* the builder to do the broadcast and return a 400 if the block
+        // is invalid.
+        let broadcast_to_bn = ctx.chain.as_ref().unwrap().spec.is_fulu_scheduled();
+
+        if use_mock_builder {
+            let mock_builder_server = harness.set_mock_builder(
+                beacon_url.clone(),
+                strict_registrations,
+                apply_operations,
+                broadcast_to_bn,
+            );
+
+            tokio::spawn(mock_builder_server);
+        }
+
         // Override the default timeout to 2s to timeouts on CI, as CI seems to require longer
         // to process. The 1s timeouts for other tasks have been working for a long time, so we'll
         // keep it as it is, as it may help identify a performance regression.
@@ -110,15 +152,7 @@ impl<E: EthSpec> InteractiveTester<E> {
             default: Duration::from_secs(2),
             ..Timeouts::set_all(Duration::from_secs(1))
         };
-        let client = BeaconNodeHttpClient::new(
-            SensitiveUrl::parse(&format!(
-                "http://{}:{}",
-                listening_socket.ip(),
-                listening_socket.port()
-            ))
-            .unwrap(),
-            timeouts,
-        );
+        let client = BeaconNodeHttpClient::new(beacon_url.clone(), timeouts);
 
         Self {
             ctx,