add a test for #507 (#508)

* add a test for #507

* CI: test uint on a big-endian platform

* a workaround for gmp

* grumbles

* bump byteorder to 1.4.2

Author: ordian

.travis.yml

@@ -18,6 +18,7 @@ matrix:
         - cargo install cross
       script:
         - cross test --target=aarch64-linux-android -p parity-util-mem
+        - cross test --target=mips64-unknown-linux-gnuabi64 -p uint
     - os: osx
       osx_image: xcode11.3
       addons:

fixed-hash/Cargo.toml

@@ -14,7 +14,7 @@ edition = "2018"
 features = ["quickcheck", "api-dummy"]
 
 [dependencies]
-byteorder = { version = "1.3.2", optional = true, default-features = false }
+byteorder = { version = "1.4.2", optional = true, default-features = false }
 quickcheck = { version = "0.9.0", optional = true }
 rand = { version = "0.8.0", optional = true, default-features = false }
 rustc-hex = { version = "2.0.1", optional = true, default-features = false }

uint/Cargo.toml

@@ -10,7 +10,7 @@ readme = "README.md"
 edition = "2018"
 
 [dependencies]
-byteorder = { version = "1.3.2", default-features = false }
+byteorder = { version = "1.4.2", default-features = false }
 crunchy = { version = "0.2.2", default-features = false }
 qc = { package = "quickcheck", version = "0.9.0", optional = true }
 rand07 = { package = "rand", version = "0.7", default-features = false, optional = true }
@@ -34,7 +34,7 @@ required-features = ["std"]
 criterion = "0.3.0"
 num-bigint = "0.3.1"
 
-[target.'cfg(unix)'.dev-dependencies]
+[target.'cfg(all(unix, target_arch = "x86_64"))'.dev-dependencies]
 rug = { version = "1.6.0", default-features = false, features = ["integer"] }
 
 [[bench]]

uint/tests/uint_tests.rs

@@ -1018,6 +1018,15 @@ fn leading_zeros() {
 	assert_eq!(U256::from("0000000000000000000000000000000000000000000000000000000000000000").leading_zeros(), 256);
 }
 
+#[test]
+fn issue_507_roundtrip() {
+	let mut b32 = <[u8; 32]>::default();
+	let a = U256::from(10);
+	a.to_little_endian(&mut b32);
+	let b = U256::from_little_endian(&b32[..]);
+	assert_eq!(a, b);
+}
+
 #[test]
 fn trailing_zeros() {
 	assert_eq!(U256::from("1adbdd6bd6ff027485484b97f8a6a4c7129756dd100000000000000000000000").trailing_zeros(), 92);