Add bones of YAML state test parsing.

Is incomplete, need to update all our types to v0.5.0 first

eth2/state_processing/tests/tests.rs

@@ -0,0 +1,42 @@
+use serde_derive::Deserialize;
+use types::*;
+
+#[derive(Debug, Deserialize)]
+pub struct TestCase {
+    pub name: String,
+    pub config: ChainSpec,
+    pub verify_signatures: bool,
+    pub initial_state: BeaconState,
+    pub blocks: Vec<BeaconBlock>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct TestDoc {
+    pub title: String,
+    pub summary: String,
+    pub fork: String,
+    pub version: String,
+    pub test_cases: Vec<TestCase>,
+}
+
+#[test]
+#[ignore]
+fn yaml() {
+    use serde_yaml;
+    use std::{fs::File, io::prelude::*, path::PathBuf};
+
+    let mut file = {
+        let mut file_path_buf = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
+        file_path_buf.push("specs/example.yml");
+
+        File::open(file_path_buf).unwrap()
+    };
+
+    let mut yaml_str = String::new();
+
+    file.read_to_string(&mut yaml_str).unwrap();
+
+    let yaml_str = yaml_str.to_lowercase();
+
+    let _doc: TestDoc = serde_yaml::from_str(&yaml_str.as_str()).unwrap();
+}