diff --git a/.github/workflows/test-suite.yml b/.github/workflows/test-suite.yml
index 72945a3..81359db 100644
--- a/.github/workflows/test-suite.yml
+++ b/.github/workflows/test-suite.yml
@@ -57,8 +57,9 @@ jobs:
     - name: Check code coverage with cargo-tarpaulin (all features)
       run: cargo-tarpaulin --workspace --out xml --skip-clean --all-features
     - name: Upload to codecov.io
-      uses: codecov/codecov-action@v3
+      uses: codecov/codecov-action@v5
+      env:
+        CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
       with:
-        fail_ci_if_error: true
-        token: ${{ secrets.CODECOV_TOKEN }}
+        fail_ci_if_error: false
         informational: true
diff --git a/src/lib.rs b/src/lib.rs
index a41443b..a139d3f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7,6 +7,9 @@
 //! Now this crate serves primarily as a wrapper over two SHA256 crates: `sha2` and `ring` – which
 //! it switches between at runtime based on the availability of SHA intrinsics.
 
+#[cfg(test)]
+mod tests;
+
 mod sha2_impl;
 
 pub use self::DynamicContext as Context;
@@ -241,33 +244,3 @@ pub static ZERO_HASHES: LazyLock<Vec<[u8; HASH_LEN]>> = LazyLock::new(|| {
 
     hashes
 });
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use rustc_hex::FromHex;
-
-    #[cfg(target_arch = "wasm32")]
-    use wasm_bindgen_test::*;
-
-    #[cfg_attr(not(target_arch = "wasm32"), test)]
-    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
-    fn test_hashing() {
-        let input: Vec<u8> = b"hello world".as_ref().into();
-
-        let output = hash(input.as_ref());
-        let expected_hex = "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9";
-        let expected: Vec<u8> = expected_hex.from_hex().unwrap();
-        assert_eq!(expected, output);
-    }
-
-    #[cfg(feature = "zero_hash_cache")]
-    mod zero_hash {
-        use super::*;
-
-        #[test]
-        fn zero_hash_zero() {
-            assert_eq!(ZERO_HASHES[0], [0; 32]);
-        }
-    }
-}
diff --git a/src/tests.rs b/src/tests.rs
new file mode 100644
index 0000000..9d42deb
--- /dev/null
+++ b/src/tests.rs
@@ -0,0 +1,108 @@
+use super::*;
+use rustc_hex::FromHex;
+
+#[cfg(target_arch = "wasm32")]
+use wasm_bindgen_test::*;
+
+#[cfg_attr(not(target_arch = "wasm32"), test)]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+fn test_hash() {
+    let output = hash(b"hello world");
+    let expected: Vec<u8> = "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
+        .from_hex()
+        .unwrap();
+    assert_eq!(expected, output);
+}
+
+#[cfg_attr(not(target_arch = "wasm32"), test)]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+fn test_hash_fixed() {
+    let output = hash_fixed(b"hello world");
+    let expected: Vec<u8> = "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
+        .from_hex()
+        .unwrap();
+    assert_eq!(expected.as_slice(), &output);
+}
+
+#[cfg_attr(not(target_arch = "wasm32"), test)]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+fn test_hash32_concat() {
+    let h1 = [0u8; 32];
+    let h2 = [1u8; 32];
+    let mut combined = Vec::new();
+    combined.extend_from_slice(&h1);
+    combined.extend_from_slice(&h2);
+    assert_eq!(hash32_concat(&h1, &h2), hash_fixed(&combined));
+}
+
+#[cfg_attr(not(target_arch = "wasm32"), test)]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+fn test_have_sha_extensions() {
+    let _ = have_sha_extensions();
+}
+
+#[cfg(feature = "ring")]
+mod ring_tests {
+    use super::*;
+
+    #[test]
+    fn test_ring_impl() {
+        let ring_impl = RingImpl;
+        let expected: Vec<u8> = "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
+            .from_hex()
+            .unwrap();
+        assert_eq!(expected, ring_impl.hash(b"hello world"));
+        assert_eq!(expected.as_slice(), &ring_impl.hash_fixed(b"hello world"));
+    }
+
+    #[test]
+    fn test_ring_context() {
+        let mut ctx: ring::digest::Context = Sha256Context::new();
+        Sha256Context::update(&mut ctx, b"hello world");
+        let expected: Vec<u8> = "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
+            .from_hex()
+            .unwrap();
+        assert_eq!(expected.as_slice(), &Sha256Context::finalize(ctx));
+    }
+}
+
+#[cfg(any(target_arch = "x86_64", feature = "sha2"))]
+mod sha2_tests {
+    use super::*;
+    use crate::sha2_impl::Sha2CrateImpl;
+
+    #[test]
+    fn test_sha2_impl() {
+        let sha2_impl = Sha2CrateImpl;
+        let expected: Vec<u8> = "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
+            .from_hex()
+            .unwrap();
+        assert_eq!(expected, sha2_impl.hash(b"hello world"));
+        assert_eq!(expected.as_slice(), &sha2_impl.hash_fixed(b"hello world"));
+    }
+
+    #[test]
+    fn test_sha2_context() {
+        let mut ctx: sha2::Sha256 = Sha256Context::new();
+        Sha256Context::update(&mut ctx, b"hello world");
+        let expected: Vec<u8> = "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
+            .from_hex()
+            .unwrap();
+        assert_eq!(expected.as_slice(), &Sha256Context::finalize(ctx));
+    }
+}
+
+#[cfg(feature = "zero_hash_cache")]
+mod zero_hash_tests {
+    use super::*;
+
+    #[test]
+    fn test_zero_hashes() {
+        assert_eq!(ZERO_HASHES[0], [0; 32]);
+        assert_eq!(
+            ZERO_HASHES[1],
+            hash32_concat(&ZERO_HASHES[0], &ZERO_HASHES[0])
+        );
+        assert_eq!(ZERO_HASHES.len(), ZERO_HASHES_MAX_INDEX + 1);
+    }
+}