tests(dmq): add fake test double for 'UnixTimestampProvider'

Author: jpraynaud

internal/mithril-dmq/src/test/double/mod.rs

@@ -4,6 +4,8 @@
 
 mod consumer;
 mod publisher;
+mod timestamp;
 
 pub use consumer::*;
 pub use publisher::*;
+pub use timestamp::*;

internal/mithril-dmq/src/test/double/timestamp.rs

@@ -0,0 +1,26 @@
+use mithril_common::StdResult;
+
+use crate::model::UnixTimestampProvider;
+
+/// Fake implementation of a Unix current timestamp provider. For testing purposes only.
+pub struct FakeUnixTimestampProvider(u64);
+
+impl FakeUnixTimestampProvider {
+    /// Creates a new `FakeUnixTimestampProvider` with the given timestamp.
+    pub fn new(timestamp: u64) -> Self {
+        Self(timestamp)
+    }
+
+    /// Computes the maximum timestamp that can be used with the given TTL and builds a new FakeUnixTimestampProvider.
+    ///
+    /// This is useful to create messages that are valid for the maximum possible time.
+    pub fn max_timestamp_for_ttl(ttl: u16) -> Self {
+        Self(u32::MAX as u64 - ttl as u64 - 1)
+    }
+}
+
+impl UnixTimestampProvider for FakeUnixTimestampProvider {
+    fn current_timestamp(&self) -> StdResult<u64> {
+        Ok(self.0)
+    }
+}