1 files changed, 65 insertions, 0 deletions
diff --git a/third_party/rust/digest/src/dev/fixed.rs b/third_party/rust/digest/src/dev/fixed.rs
new file mode 100644
index 0000000000..24f380112d
--- /dev/null
+++ b/third_party/rust/digest/src/dev/fixed.rs
@@ -0,0 +1,65 @@
+use crate::{Digest, FixedOutput, FixedOutputReset, HashMarker, Update};
+use core::fmt::Debug;
+
+/// Fixed-output resettable digest test via the `Digest` trait
+pub fn fixed_reset_test<D>(input: &[u8], output: &[u8]) -> Option<&'static str>
+where
+    D: FixedOutputReset + Debug + Clone + Default + Update + HashMarker,
+{
+    let mut hasher = D::new();
+    // Test that it works when accepting the message all at once
+    hasher.update(input);
+    let mut hasher2 = hasher.clone();
+    if hasher.finalize()[..] != output[..] {
+        return Some("whole message");
+    }
+
+    // Test if reset works correctly
+    hasher2.reset();
+    hasher2.update(input);
+    if hasher2.finalize_reset()[..] != output[..] {
+        return Some("whole message after reset");
+    }
+
+    // Test that it works when accepting the message in chunks
+    for n in 1..core::cmp::min(17, input.len()) {
+        let mut hasher = D::new();
+        for chunk in input.chunks(n) {
+            hasher.update(chunk);
+            hasher2.update(chunk);
+        }
+        if hasher.finalize()[..] != output[..] {
+            return Some("message in chunks");
+        }
+        if hasher2.finalize_reset()[..] != output[..] {
+            return Some("message in chunks");
+        }
+    }
+
+    None
+}
+
+/// Variable-output resettable digest test
+pub fn fixed_test<D>(input: &[u8], output: &[u8]) -> Option<&'static str>
+where
+    D: FixedOutput + Default + Debug + Clone,
+{
+    let mut hasher = D::default();
+    // Test that it works when accepting the message all at once
+    hasher.update(input);
+    if hasher.finalize_fixed()[..] != output[..] {
+        return Some("whole message");
+    }
+
+    // Test that it works when accepting the message in chunks
+    for n in 1..core::cmp::min(17, input.len()) {
+        let mut hasher = D::default();
+        for chunk in input.chunks(n) {
+            hasher.update(chunk);
+        }
+        if hasher.finalize_fixed()[..] != output[..] {
+            return Some("message in chunks");
+        }
+    }
+    None
+}