From 3d469e138340b7743f5a0695059b2b163edb149e Mon Sep 17 00:00:00 2001
From: Guillaume Leroy <pro.guillaume.leroy@gmail.com>
Date: Tue, 19 Sep 2023 17:01:03 +0200
Subject: [PATCH] feat: add clock

---
 Cargo.toml   |  3 +++
 src/clock.rs | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs   |  8 ++++++
 3 files changed, 81 insertions(+)
 create mode 100644 src/clock.rs

diff --git a/Cargo.toml b/Cargo.toml
index dd83e83..9d738a7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,7 +10,10 @@ keywords = ["mock", "mockable", "mocking", "test"]
 categories = ["development-tools::testing"]
 
 [features]
+clock = ["dep:chrono"]
+full = ["clock"]
 mock = ["dep:mockall"]
 
 [dependencies]
+chrono = { version = "0.4", optional = true }
 mockall = { version = "0.11", optional = true }
diff --git a/src/clock.rs b/src/clock.rs
new file mode 100644
index 0000000..9b57cde
--- /dev/null
+++ b/src/clock.rs
@@ -0,0 +1,70 @@
+use chrono::{DateTime, Local, Utc};
+use mockall::mock;
+
+// Clock
+
+/// A trait for getting the current time.
+///
+/// **This is supported on `feature=clock` only.**
+/// # Examples
+///
+/// ```
+/// use chrono::{DateTime, Utc, Duration};
+/// use mockable::{Clock, DefaultClock, MockClock};
+///
+/// fn now(clock: &dyn Clock) -> DateTime<Utc> {
+///    clock.utc()
+/// }
+///
+/// // Default
+/// let time = now(&DefaultClock);
+/// assert!(time < Utc::now() + Duration::seconds(1));
+///
+/// // Mock
+/// let expected = Utc::now();
+/// let mut clock = MockClock::new();
+/// clock
+///     .expect_utc()
+///     .returning(move || expected);
+/// let time = now(&clock);
+/// assert_eq!(time, expected);
+/// ```
+pub trait Clock: Send + Sync {
+    /// Returns the current time in the local timezone.
+    fn local(&self) -> DateTime<Local>;
+
+    /// Returns the current time in UTC.
+    fn utc(&self) -> DateTime<Utc>;
+}
+
+// DefaultClock
+
+/// Default implementation of `Clock`.
+///
+/// **This is supported on `feature=clock` only.**
+pub struct DefaultClock;
+
+impl Clock for DefaultClock {
+    fn local(&self) -> DateTime<Local> {
+        Local::now()
+    }
+
+    fn utc(&self) -> DateTime<Utc> {
+        Utc::now()
+    }
+}
+
+// MockClock
+
+#[cfg(feature = "mock")]
+mock! {
+    /// `mockall` implementation of `Clock`.
+    ///
+    /// **This is supported on `feature=clock,mock` only.**
+    pub Clock {}
+
+    impl super::Clock for Clock {
+        fn local(&self) -> DateTime<Local>;
+        fn utc(&self) -> DateTime<Utc>;
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 8b13789..92568d9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1 +1,9 @@
+// Re-use
 
+#[cfg(feature = "clock")]
+pub use self::clock::*;
+
+// Mods
+
+#[cfg(feature = "clock")]
+mod clock;