add a test for the new serde feature

.github/workflows/ci.yml

@@ -52,17 +52,17 @@ jobs:
     - name: print instruction set support
       run: cargo run --quiet
       working-directory: ./tools/instruction_set_support
-    # Default tests plus Rayon and RustCrypto trait implementations.
-    - run: cargo test --features=rayon,traits-preview,zeroize
+    # Default tests plus Rayon and trait implementations.
+    - run: cargo test --features=rayon,traits-preview,serde,zeroize
     # Same but with only one thread in the Rayon pool. This can find deadlocks.
     - name: "again with RAYON_NUM_THREADS=1"
-      run: cargo test --features=rayon,traits-preview,zeroize
+      run: cargo test --features=rayon,traits-preview,serde,zeroize
       env:
         RAYON_NUM_THREADS: 1
     # The mmap feature by itself (update_mmap_rayon is omitted).
     - run: cargo test --features=mmap
     # All public features put together.
-    - run: cargo test --features=mmap,rayon,traits-preview,zeroize
+    - run: cargo test --features=mmap,rayon,traits-preview,serde,zeroize
     # no_std tests.
     - run: cargo test --no-default-features
 

Cargo.toml

@@ -88,8 +88,8 @@ no_avx512 = []
 no_neon = []
 
 [package.metadata.docs.rs]
-# Document the rayon/mmap methods and the Zeroize impls on docs.rs.
-features = ["mmap", "rayon", "zeroize"]
+# Document the rayon/mmap methods and the Serialize/Deserialize/Zeroize impls on docs.rs.
+features = ["mmap", "rayon", "serde", "zeroize"]
 
 [dependencies]
 arrayref = "0.3.5"
@@ -110,6 +110,7 @@ rand = "0.8.0"
 rand_chacha = "0.3.0"
 reference_impl = { path = "./reference_impl" }
 tempfile = "3.8.0"
+serde_json = "1.0.107"
 
 [build-dependencies]
 cc = "1.0.4"

src/lib.rs

@@ -56,6 +56,11 @@
 //! [`Zeroize`](https://docs.rs/zeroize/latest/zeroize/trait.Zeroize.html) for
 //! this crate's types.
 //!
+//! The `serde` feature (disabled by default, but enabled for [docs.rs]) implements
+//! [`serde::Serialize`](https://docs.rs/serde/latest/serde/trait.Serialize.html) and
+//! [`serde::Deserialize`](https://docs.rs/serde/latest/serde/trait.Deserialize.html)
+//! for [`Hash`](struct@Hash).
+//!
 //! The NEON implementation is enabled by default for AArch64 but requires the
 //! `neon` feature for other ARM targets. Not all ARMv7 CPUs support NEON, and
 //! enabling this feature will produce a binary that's not portable to CPUs
@@ -69,9 +74,6 @@
 //! expect breaking changes between patch versions. (The "-preview" feature name
 //! follows the conventions of the RustCrypto [`signature`] crate.)
 //!
-//! The `serde` feature (disabled by default) enables serde compatibility for
-//! the `Hash` struct.
-//!
 //! [`Hasher::update_rayon`]: struct.Hasher.html#method.update_rayon
 //! [BLAKE3]: https://blake3.io
 //! [Rayon]: https://github.com/rayon-rs/rayon

src/test.rs

@@ -806,3 +806,17 @@ fn test_mmap_rayon() -> Result<(), std::io::Error> {
     );
     Ok(())
 }
+
+#[test]
+#[cfg(feature = "std")]
+#[cfg(feature = "serde")]
+fn test_serde() {
+    let hash: crate::Hash = [7; 32].into();
+    let json = serde_json::to_string(&hash).unwrap();
+    assert_eq!(
+        json,
+        "[7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7]",
+    );
+    let hash2: crate::Hash = serde_json::from_str(&json).unwrap();
+    assert_eq!(hash, hash2);
+}