diff --git a/Cargo.lock b/Cargo.lock
index 6237a3660..e3919220d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -559,6 +559,7 @@ dependencies = [
  "regex",
  "rlimit",
  "rstest",
+ "rstest_reuse",
  "rustc-hash",
  "selinux",
  "sha1",
@@ -2558,6 +2559,17 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "rstest_reuse"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b3a8fb4672e840a587a66fc577a5491375df51ddb88f2a2c2a792598c326fe14"
+dependencies = [
+ "quote",
+ "rand 0.8.5",
+ "syn",
+]
+
 [[package]]
 name = "rust-ini"
 version = "0.21.3"
diff --git a/Cargo.toml b/Cargo.toml
index 92013b0af..9ef80cd07 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -432,6 +432,7 @@ rayon = "1.10"
 regex = "1.10.4"
 rlimit = "0.11.0"
 rstest = "0.26.0"
+rstest_reuse = "0.7.0"
 rustc-hash = "2.1.1"
 rust-ini = "0.21.0"
 same-file = "1.0.6"
@@ -640,6 +641,7 @@ uucore = { workspace = true, features = [
 walkdir.workspace = true
 hex-literal = "1.0.0"
 rstest.workspace = true
+rstest_reuse.workspace = true
 
 [target.'cfg(unix)'.dev-dependencies]
 nix = { workspace = true, features = [
diff --git a/tests/by-util/test_cksum.rs b/tests/by-util/test_cksum.rs
index 67f96e907..1ab5bb452 100644
--- a/tests/by-util/test_cksum.rs
+++ b/tests/by-util/test_cksum.rs
@@ -5,6 +5,7 @@
 // spell-checker:ignore (words) asdf algo algos asha mgmt xffname hexa GFYEQ HYQK Yqxb dont checkfile
 
 use rstest::rstest;
+use rstest_reuse::{apply, template};
 
 use uutests::at_and_ucmd;
 use uutests::new_ucmd;
@@ -3287,3 +3288,112 @@ fn test_check_shake256_no_length() {
         .fails()
         .stderr_only("cksum: 'standard input': no properly formatted checksum lines found\n");
 }
+
+#[template]
+#[rstest]
+#[case::no_length(
+    b"foo",
+    "04e0bb39f30b1a3feb89f536c93be15055482df748674b00d26e5a75777702e9",
+    None
+)]
+#[case(
+    b"foo",
+    "04e0bb39f30b1a3feb89f536c93be15055482df748674b00d26e5a75777702e9",
+    Some(0)
+)]
+#[case(
+    b"foo",
+    "04e0bb39f30b1a3feb89f536c93be15055482df748674b00d26e5a75777702e9",
+    Some(256)
+)]
+#[case(
+    b"foo",
+    "04e0bb39f30b1a3feb89f536c93be15055482df748674b00d26e5a75777702e9791074b7511b59d31c71c62f5a745689fa6c",
+    Some(400)
+)]
+#[case(b"foo", "04e0bb39f3", Some(40))]
+#[case(b"foo", "04e0", Some(16))]
+#[case(b"foo", "04", Some(8))]
+fn test_blake3(#[case] input: &[u8], #[case] expected: &str, #[case] length: Option<usize>) {}
+
+#[apply(test_blake3)]
+fn test_compute_blake3(
+    #[case] input: &[u8],
+    #[case] expected: &str,
+    #[case] length: Option<usize>,
+) {
+    let length_args: &[String] = if let Some(len) = length {
+        &["-l".into(), len.to_string()]
+    } else {
+        &[]
+    };
+
+    new_ucmd!()
+        .arg("-a")
+        .arg("blake3")
+        .args(length_args)
+        .pipe_in(input)
+        .succeeds()
+        .stdout_only(format!(
+            "BLAKE3{} (-) = {expected}\n",
+            match length {
+                Some(0) | None => "-256".into(),
+                Some(i) => format!("-{i}"),
+            }
+        ));
+
+    // with --untagged
+    new_ucmd!()
+        .arg("-a")
+        .arg("blake3")
+        .arg("--untagged")
+        .args(length_args)
+        .pipe_in(input)
+        .succeeds()
+        .stdout_only(format!("{expected}  -\n"));
+}
+
+#[apply(test_blake3)]
+fn test_check_blake3_tagged(
+    #[case] input: &[u8],
+    #[case] digest: &str,
+    #[case] opt_len: Option<usize>,
+) {
+    let (at, mut ucmd) = at_and_ucmd!();
+    at.write_bytes("FILE", input);
+
+    let len = match opt_len {
+        Some(0) => "-256".into(),
+        Some(i) => format!("-{i}"),
+        None => String::new(),
+    };
+
+    let tagged = format!("BLAKE3{len} (FILE) = {digest}",);
+
+    ucmd.arg("-c")
+        .arg("-a")
+        .arg("blake3")
+        .pipe_in(tagged)
+        .succeeds()
+        .stdout_only("FILE: OK\n");
+}
+
+#[apply(test_blake3)]
+#[allow(clippy::used_underscore_binding)]
+fn test_check_blake3_untagged(
+    #[case] input: &[u8],
+    #[case] digest: &str,
+    #[case] _opt_len: Option<usize>,
+) {
+    let (at, mut ucmd) = at_and_ucmd!();
+    at.write_bytes("FILE", input);
+
+    let untagged = format!("{digest} FILE");
+
+    ucmd.arg("-c")
+        .arg("-a")
+        .arg("blake3")
+        .pipe_in(untagged)
+        .succeeds()
+        .stdout_only("FILE: OK\n");
+}