Add arbitraries

This is incomplete as long as multiformats/rust-multihash#51 is not merged

Author: rklaehn

Cargo.toml

@@ -22,3 +22,12 @@ no-dev-version = true
 multihash = "~0.8.0"
 multibase = "~0.6.0"
 integer-encoding = "~1.0.3"
+quickcheck = { version = "0.9.2", optional = true }
+rand = { version = "0.7.3", optional = true }
+
+[dev-dependencies]
+quickcheck = "0.9.2"
+rand = "0.7.3"
+
+[features]
+test = ["quickcheck", "rand"]

src/arb.rs

@@ -0,0 +1,73 @@
+use crate::{Cid, Codec, Prefix, Version};
+use quickcheck::{Arbitrary, Gen};
+use rand::seq::SliceRandom;
+use rand::Rng;
+
+const CODECS: [Codec; 18] = [
+    Codec::Raw,
+    Codec::DagProtobuf,
+    Codec::DagCBOR,
+    Codec::GitRaw,
+    Codec::EthereumBlock,
+    Codec::EthereumBlockList,
+    Codec::EthereumTxTrie,
+    Codec::EthereumTx,
+    Codec::EthereumTxReceiptTrie,
+    Codec::EthereumTxReceipt,
+    Codec::EthereumStateTrie,
+    Codec::EthereumAccountSnapshot,
+    Codec::EthereumStorageTrie,
+    Codec::BitcoinBlock,
+    Codec::BitcoinTx,
+    Codec::ZcashBlock,
+    Codec::ZcashTx,
+    Codec::DagJSON,
+];
+
+const POPULAR: [Codec; 4] = [
+    Codec::Raw,
+    Codec::DagProtobuf,
+    Codec::DagCBOR,
+    Codec::DagJSON,
+];
+
+impl Arbitrary for Codec {
+    fn arbitrary<G: Gen>(g: &mut G) -> Self {
+        // chose the most frequently used codecs more often
+        if g.gen_bool(0.7) {
+            *POPULAR.choose(g).unwrap()
+        } else {
+            *CODECS.choose(g).unwrap()
+        }
+    }
+}
+
+impl Arbitrary for Prefix {
+    fn arbitrary<G: Gen>(g: &mut G) -> Self {
+        let version = if g.gen_bool(0.7) { 1 } else { 0 };
+        let codec: Codec = if version == 1 {
+            // v1 supports arbitrary encodings
+            Arbitrary::arbitrary(g)
+        } else {
+            // v0 does only support DagProtobuf encoding
+            Codec::DagProtobuf
+        };
+        let version = Version::from(version).unwrap();
+        Prefix {
+            version,
+            codec,
+            // todo: randomize this once https://github.com/multiformats/rust-multihash/pull/51 is merged
+            mh_type: multihash::Hash::SHA2256,
+            mh_len: 32,
+        }
+    }
+}
+
+impl Arbitrary for Cid {
+    fn arbitrary<G: Gen>(g: &mut G) -> Self {
+        let mut hash = [0u8; 32];
+        g.fill_bytes(&mut hash);
+        let prefix: Prefix = Arbitrary::arbitrary(g);
+        Cid::new_from_prefix(&prefix, &hash)
+    }
+}

src/error.rs

@@ -1,6 +1,6 @@
-use std::{fmt, error, io};
 use multibase;
 use multihash;
+use std::{error, fmt, io};
 
 pub type Result<T> = ::std::result::Result<T, Error>;
 

src/lib.rs

@@ -2,19 +2,17 @@
 /// !
 /// ! Implementation of [cid](https://github.com/ipld/cid) in Rust.
 
-extern crate multihash;
-extern crate multibase;
-extern crate integer_encoding;
-
-mod to_cid;
-mod error;
+#[cfg(any(test, feature = "test"))]
+mod arb;
 mod codec;
+mod error;
+mod to_cid;
 mod version;
 
-pub use to_cid::ToCid;
-pub use version::Version;
 pub use codec::Codec;
 pub use error::{Error, Result};
+pub use to_cid::ToCid;
+pub use version::Version;
 
 use integer_encoding::{VarIntReader, VarIntWriter};
 use std::fmt;

src/to_cid.rs

@@ -1,10 +1,10 @@
-use std::io::Cursor;
-use std::str::FromStr;
+use integer_encoding::VarIntReader;
 use multibase;
 use multihash;
-use integer_encoding::VarIntReader;
+use std::io::Cursor;
+use std::str::FromStr;
 
-use crate::{Cid, Version, Codec, Error, Result};
+use crate::{Cid, Codec, Error, Result, Version};
 
 pub trait ToCid {
     fn to_cid(&self) -> Result<Cid>;
@@ -39,7 +39,7 @@ impl ToCid for str {
 
         let hash = match self.find(IPFS_DELIMETER) {
             Some(index) => &self[index + IPFS_DELIMETER.len()..],
-            _ => self
+            _ => self,
         };
 
         if hash.len() < 2 {
@@ -60,7 +60,6 @@ impl ToCid for str {
     }
 }
 
-
 impl FromStr for Cid {
     type Err = Error;
     fn from_str(src: &str) -> Result<Self> {

src/version.rs

@@ -13,7 +13,7 @@ impl Version {
         match raw {
             0 => Ok(V0),
             1 => Ok(V1),
-            _ => Err(Error::InvalidCidVersion)
+            _ => Err(Error::InvalidCidVersion),
         }
     }
 
@@ -24,7 +24,7 @@ impl Version {
     }
 
     pub fn is_v0_binary(data: &[u8]) -> bool {
-        data.len() == 34 && data.starts_with(&[0x12,0x20])
+        data.len() == 34 && data.starts_with(&[0x12, 0x20])
     }
 }
 

tests/lib.rs

@@ -1,7 +1,7 @@
 extern crate cid;
 extern crate multihash;
 
-use cid::{Cid, Version, Codec, Error, Prefix};
+use cid::{Cid, Codec, Error, Prefix, Version};
 use std::collections::HashMap;
 
 #[test]
@@ -37,7 +37,9 @@ fn v0_handling() {
 
 #[test]
 fn from_str() {
-    let cid: Cid = "QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zR1n".parse().unwrap();
+    let cid: Cid = "QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zR1n"
+        .parse()
+        .unwrap();
     assert_eq!(cid.version, Version::V0);
 
     let bad = "QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zIII".parse::<Cid>();