Add v0.8 genesis tests (#466)

Closes #452

tests/ef_tests/src/cases/genesis_validity.rs

@@ -0,0 +1,42 @@
+use super::*;
+use crate::bls_setting::BlsSetting;
+use serde_derive::Deserialize;
+use state_processing::is_valid_genesis_state;
+use types::{BeaconState, EthSpec};
+
+#[derive(Debug, Clone, Deserialize)]
+#[serde(bound = "E: EthSpec")]
+pub struct GenesisValidity<E: EthSpec> {
+    pub description: String,
+    pub bls_setting: Option<BlsSetting>,
+    pub genesis: BeaconState<E>,
+    pub is_valid: bool,
+}
+
+impl<E: EthSpec> YamlDecode for GenesisValidity<E> {
+    fn yaml_decode(yaml: &str) -> Result<Self, Error> {
+        Ok(serde_yaml::from_str(yaml).unwrap())
+    }
+}
+
+impl<E: EthSpec> Case for GenesisValidity<E> {
+    fn description(&self) -> String {
+        self.description.clone()
+    }
+
+    fn result(&self, _case_index: usize) -> Result<(), Error> {
+        self.bls_setting.unwrap_or_default().check()?;
+        let spec = &E::default_spec();
+
+        let is_valid = is_valid_genesis_state(&self.genesis, spec);
+
+        if is_valid == self.is_valid {
+            Ok(())
+        } else {
+            Err(Error::NotEqual(format!(
+                "Got {}, expected {}",
+                is_valid, self.is_valid
+            )))
+        }
+    }
+}