Introduce toy runtime for testing inside substrate. (#66)

* Introduce simple blockchain runtime for substrate tests.

* Remove bad files.

* Add needed wasm binaries.

* Refactoring.

- Repot files in test-runtime.
- Rename troublesome `Joiner::join` to `Joiner::and`.
- Rework `Slicable` to dedup code.

* More fixes and refactoring

* Rebuild substrate test wasm.

* Fix merge errors.

* Rename the disasterously named `to_vec` to `encode`.

Also rename `as_slice_then` to `with_encoded`.

* Tests for toy runtime.

* Fix doc nit

substrate/polkadot/primitives/src/block.rs

@@ -42,8 +42,8 @@ impl Slicable for Log {
 		Vec::<u8>::decode(input).map(Log)
 	}
 
-	fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
-		self.0.as_slice_then(f)
+	fn using_encoded<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
+		self.0.using_encoded(f)
 	}
 }
 
@@ -62,8 +62,8 @@ impl Slicable for Digest {
 		Vec::<Log>::decode(input).map(|logs| Digest { logs })
 	}
 
-	fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
-		self.logs.as_slice_then(f)
+	fn using_encoded<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
+		self.logs.using_encoded(f)
 	}
 }
 
@@ -86,18 +86,14 @@ impl Slicable for Block {
 		Some(Block { header, transactions })
 	}
 
-	fn to_vec(&self) -> Vec<u8> {
+	fn encode(&self) -> Vec<u8> {
 		let mut v = Vec::new();
 
-		v.extend(self.header.to_vec());
-		v.extend(self.transactions.to_vec());
+		v.extend(self.header.encode());
+		v.extend(self.transactions.encode());
 
 		v
 	}
-
-	fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
-		f(self.to_vec().as_slice())
-	}
 }
 
 /// A relay chain block header.
@@ -144,21 +140,17 @@ impl Slicable for Header {
 		})
 	}
 
-	fn to_vec(&self) -> Vec<u8> {
+	fn encode(&self) -> Vec<u8> {
 		let mut v = Vec::new();
 
-		self.parent_hash.as_slice_then(|s| v.extend(s));
-		self.number.as_slice_then(|s| v.extend(s));
-		self.state_root.as_slice_then(|s| v.extend(s));
-		self.transaction_root.as_slice_then(|s| v.extend(s));
-		self.digest.as_slice_then(|s| v.extend(s));
+		self.parent_hash.using_encoded(|s| v.extend(s));
+		self.number.using_encoded(|s| v.extend(s));
+		self.state_root.using_encoded(|s| v.extend(s));
+		self.transaction_root.using_encoded(|s| v.extend(s));
+		self.digest.using_encoded(|s| v.extend(s));
 
 		v
 	}
-
-	fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
-		f(self.to_vec().as_slice())
-	}
 }
 
 #[cfg(test)]
@@ -189,7 +181,7 @@ mod tests {
   }
 }"#);
 
-		let v = header.to_vec();
+		let v = header.encode();
 		assert_eq!(Header::decode(&mut &v[..]).unwrap(), header);
 	}
 }