ps_uuid/methods/
nil.rs

1use crate::{UUID, UUID_BYTES};
2
3impl UUID {
4    #[must_use]
5    pub const fn nil() -> Self {
6        Self {
7            bytes: [0; UUID_BYTES],
8        }
9    }
10}
11
12#[cfg(test)]
13mod tests {
14    use super::*;
15
16    /// Tests that the `nil()` function correctly produces a UUID with all
17    /// zero bytes.
18    #[test]
19    fn test_nil_is_all_zeros() {
20        let nil_uuid = UUID::nil();
21        let expected_bytes = [0u8; UUID_BYTES];
22        assert_eq!(
23            nil_uuid.bytes, expected_bytes,
24            "The bytes of a nil UUID should all be zero"
25        );
26    }
27
28    /// Tests that the `nil()` function is deterministic and that two generated
29    /// nil UUIDs are equal to each other.
30    #[test]
31    fn test_nil_is_deterministic() {
32        let nil1 = UUID::nil();
33        let nil2 = UUID::nil();
34        assert_eq!(nil1, nil2, "Two nil UUIDs should be equal");
35    }
36
37    /// This test verifies the `const` nature of the `nil()` function.
38    /// The test logic itself is trivial; the key is that the code *compiles*.
39    /// By successfully assigning the result of `UUID::nil()` to a `const`
40    /// item, we prove that it can be evaluated at compile time.
41    #[test]
42    fn test_nil_can_be_used_in_const_context() {
43        const COMPILE_TIME_NIL: UUID = UUID::nil();
44        const EXPECTED_NIL: UUID = UUID {
45            bytes: [0; UUID_BYTES],
46        };
47
48        // This assertion is somewhat redundant if the other tests pass,
49        // but it completes the test case.
50        assert_eq!(
51            COMPILE_TIME_NIL, EXPECTED_NIL,
52            "A const-evaluated nil UUID should match the expected value"
53        );
54
55        // We can also use it directly in a match arm or other const places.
56        match UUID::nil() {
57            COMPILE_TIME_NIL => (), // This arm must match
58            _ => panic!("A const nil UUID should match UUID::nil()"),
59        }
60    }
61}
ps_uuid/methods/nil.rs

ps_uuid/methods/
nil.rs
