handling invalid spec jsons properly, additional tests, closes #1840

ethcore/src/engines/basic_authority.rs

@@ -187,7 +187,10 @@ mod tests {
 	use spec::Spec;
 
 	/// Create a new test chain spec with `BasicAuthority` consensus engine.
-	fn new_test_authority() -> Spec { Spec::load(include_bytes!("../../res/test_authority.json")) }
+	fn new_test_authority() -> Spec {
+		let bytes: &[u8] = include_bytes!("../../res/test_authority.json");
+		Spec::load(bytes).expect("invalid chain spec")
+	}
 
 	#[test]
 	fn has_valid_metadata() {

ethcore/src/engines/instant_seal.rs

@@ -72,7 +72,10 @@ mod tests {
 	use block::*;
 
 	/// Create a new test chain spec with `BasicAuthority` consensus engine.
-	fn new_test_instant() -> Spec { Spec::load(include_bytes!("../../res/instant_seal.json")) }
+	fn new_test_instant() -> Spec {
+		let bytes: &[u8] = include_bytes!("../../res/instant_seal.json");
+		Spec::load(bytes).expect("invalid chain spec")
+	}
 
 	#[test]
 	fn instant_can_seal() {

ethcore/src/ethereum/mod.rs

@@ -29,29 +29,33 @@ pub use self::denominations::*;
 
 use super::spec::*;
 
+fn load(b: &[u8]) -> Spec {
+	Spec::load(b).expect("chain spec is invalid")
+}
+
 /// Create a new Olympic chain spec.
-pub fn new_olympic() -> Spec { Spec::load(include_bytes!("../../res/ethereum/olympic.json")) }
+pub fn new_olympic() -> Spec { load(include_bytes!("../../res/ethereum/olympic.json")) }
 
 /// Create a new Frontier mainnet chain spec.
-pub fn new_frontier() -> Spec { Spec::load(include_bytes!("../../res/ethereum/frontier.json")) }
+pub fn new_frontier() -> Spec { load(include_bytes!("../../res/ethereum/frontier.json")) }
 
 /// Create a new Frontier mainnet chain spec without the DAO hardfork.
-pub fn new_classic() -> Spec { Spec::load(include_bytes!("../../res/ethereum/classic.json")) }
+pub fn new_classic() -> Spec { load(include_bytes!("../../res/ethereum/classic.json")) }
 
 /// Create a new Frontier chain spec as though it never changes to Homestead.
-pub fn new_frontier_test() -> Spec { Spec::load(include_bytes!("../../res/ethereum/frontier_test.json")) }
+pub fn new_frontier_test() -> Spec { load(include_bytes!("../../res/ethereum/frontier_test.json")) }
 
 /// Create a new Homestead chain spec as though it never changed from Frontier.
-pub fn new_homestead_test() -> Spec { Spec::load(include_bytes!("../../res/ethereum/homestead_test.json")) }
+pub fn new_homestead_test() -> Spec { load(include_bytes!("../../res/ethereum/homestead_test.json")) }
 
 /// Create a new Frontier/Homestead/DAO chain spec with transition points at #5 and #8.
-pub fn new_daohardfork_test() -> Spec { Spec::load(include_bytes!("../../res/ethereum/daohardfork_test.json")) }
+pub fn new_daohardfork_test() -> Spec { load(include_bytes!("../../res/ethereum/daohardfork_test.json")) }
 
 /// Create a new Frontier main net chain spec without genesis accounts.
-pub fn new_mainnet_like() -> Spec { Spec::load(include_bytes!("../../res/ethereum/frontier_like_test.json")) }
+pub fn new_mainnet_like() -> Spec { load(include_bytes!("../../res/ethereum/frontier_like_test.json")) }
 
 /// Create a new Morden chain spec.
-pub fn new_morden() -> Spec { Spec::load(include_bytes!("../../res/ethereum/morden.json")) }
+pub fn new_morden() -> Spec { load(include_bytes!("../../res/ethereum/morden.json")) }
 
 #[cfg(test)]
 mod tests {

ethcore/src/spec/spec.rs

@@ -244,18 +244,21 @@ impl Spec {
 	}
 
 	/// Loads spec from json file.
-	pub fn load(reader: &[u8]) -> Self {
-		From::from(ethjson::spec::Spec::load(reader).expect("invalid json file"))
+	pub fn load<R>(reader: R) -> Result<Self, String> where R: Read {
+		match ethjson::spec::Spec::load(reader) {
+			Ok(spec) => Ok(spec.into()),
+			_ => Err("Spec json is invalid".into()),
+		}
 	}
 
 	/// Create a new Spec which conforms to the Frontier-era Morden chain except that it's a NullEngine consensus.
-	pub fn new_test() -> Spec {
-		Spec::load(include_bytes!("../../res/null_morden.json"))
+	pub fn new_test() -> Self {
+		Spec::load(include_bytes!("../../res/null_morden.json") as &[u8]).expect("null_morden.json is invalid")
 	}
 
 	/// Create a new Spec which is a NullEngine consensus with a premine of address whose secret is sha3('').
-	pub fn new_null() -> Spec {
-		Spec::load(include_bytes!("../../res/null.json"))
+	pub fn new_null() -> Self {
+		Spec::load(include_bytes!("../../res/null.json") as &[u8]).expect("null.json is invalid")
 	}
 }
 
@@ -267,6 +270,12 @@ mod tests {
 	use views::*;
 	use super::*;
 
+	// https://github.com/ethcore/parity/issues/1840
+	#[test]
+	fn test_load_empty() {
+		assert!(Spec::load(&vec![] as &[u8]).is_err());
+	}
+
 	#[test]
 	fn test_chain() {
 		let test_spec = Spec::new_test();