Fix naming consistency with attester crate.

Adjusted naming of files to ensure they match the name of the struct.
Also change the name of some structs so they don't look like tests.

eth2/attester/src/test_utils/simulated_beacon_node.rs

@@ -0,0 +1,44 @@
+use crate::traits::{BeaconNode, BeaconNodeError, PublishOutcome};
+use std::sync::RwLock;
+use types::{AttestationData, FreeAttestation};
+
+type ProduceResult = Result<Option<AttestationData>, BeaconNodeError>;
+type PublishResult = Result<PublishOutcome, BeaconNodeError>;
+
+/// A test-only struct used to simulate a Beacon Node.
+#[derive(Default)]
+pub struct SimulatedBeaconNode {
+    pub produce_input: RwLock<Option<(u64, u64)>>,
+    pub produce_result: RwLock<Option<ProduceResult>>,
+
+    pub publish_input: RwLock<Option<FreeAttestation>>,
+    pub publish_result: RwLock<Option<PublishResult>>,
+}
+
+impl SimulatedBeaconNode {
+    pub fn set_next_produce_result(&self, result: ProduceResult) {
+        *self.produce_result.write().unwrap() = Some(result);
+    }
+
+    pub fn set_next_publish_result(&self, result: PublishResult) {
+        *self.publish_result.write().unwrap() = Some(result);
+    }
+}
+
+impl BeaconNode for SimulatedBeaconNode {
+    fn produce_attestation_data(&self, slot: u64, shard: u64) -> ProduceResult {
+        *self.produce_input.write().unwrap() = Some((slot, shard));
+        match *self.produce_result.read().unwrap() {
+            Some(ref r) => r.clone(),
+            None => panic!("TestBeaconNode: produce_result == None"),
+        }
+    }
+
+    fn publish_attestation_data(&self, free_attestation: FreeAttestation) -> PublishResult {
+        *self.publish_input.write().unwrap() = Some(free_attestation.clone());
+        match *self.publish_result.read().unwrap() {
+            Some(ref r) => r.clone(),
+            None => panic!("TestBeaconNode: publish_result == None"),
+        }
+    }
+}