feat: add library lifecycle utility in omrf

omrf/tests/library_lifecycle.rs

@@ -0,0 +1,141 @@
+//! Integration tests for the `library_lifecycle` module.
+
+use sarasacw_omrf::library_lifecycle::LibraryLifecycle;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use thiserror::Error as TeError;
+
+#[derive(Debug, TeError)]
+enum TestErr {
+    #[error("boom")]
+    Boom,
+}
+
+#[derive(Debug)]
+struct State {
+    value: usize,
+}
+
+/// Coverage: a single paired startup/shutdown runs init once and destroy once, destroy receives the
+/// state produced by init, and the count returns to zero.
+#[test]
+fn paired_startup_shutdown() {
+    let inits = AtomicUsize::new(0);
+    let destroys = AtomicUsize::new(0);
+    let lc: LibraryLifecycle<State> = LibraryLifecycle::new();
+
+    lc.startup(|| -> Result<State, TestErr> {
+        inits.fetch_add(1, Ordering::SeqCst);
+        Ok(State { value: 42 })
+    })
+    .unwrap();
+
+    lc.shutdown(|s| {
+        destroys.fetch_add(1, Ordering::SeqCst);
+        assert_eq!(s.value, 42);
+    })
+    .unwrap();
+
+    assert_eq!(inits.load(Ordering::SeqCst), 1);
+    assert_eq!(destroys.load(Ordering::SeqCst), 1);
+    assert_eq!(lc.count(), 0);
+}
+
+/// Coverage: multiple startups followed by matching shutdowns run init and destroy only on the
+/// boundary transitions (once each); the init/destroy closures passed on non-transition calls are
+/// dropped without being run.
+#[test]
+fn multiple_startups_shutdowns_run_only_on_boundaries() {
+    let inits = AtomicUsize::new(0);
+    let destroys = AtomicUsize::new(0);
+    let lc: LibraryLifecycle<State> = LibraryLifecycle::new();
+
+    for _ in 0..3 {
+        lc.startup(|| -> Result<State, TestErr> {
+            inits.fetch_add(1, Ordering::SeqCst);
+            Ok(State { value: 7 })
+        })
+        .unwrap();
+    }
+    assert_eq!(lc.count(), 3);
+    assert_eq!(inits.load(Ordering::SeqCst), 1);
+
+    for _ in 0..3 {
+        lc.shutdown(|_s| {
+            destroys.fetch_add(1, Ordering::SeqCst);
+        })
+        .unwrap();
+    }
+
+    assert_eq!(inits.load(Ordering::SeqCst), 1);
+    assert_eq!(destroys.load(Ordering::SeqCst), 1);
+    assert_eq!(lc.count(), 0);
+}
+
+/// Coverage: after a full cycle, a new cycle re-runs init and destroy (re-initialization works).
+#[test]
+fn reinitialization_runs_init_and_destroy_again() {
+    let inits = AtomicUsize::new(0);
+    let destroys = AtomicUsize::new(0);
+    let lc: LibraryLifecycle<State> = LibraryLifecycle::new();
+
+    for _ in 0..2 {
+        lc.startup(|| -> Result<State, TestErr> {
+            inits.fetch_add(1, Ordering::SeqCst);
+            Ok(State { value: 1 })
+        })
+        .unwrap();
+        lc.shutdown(|_s| {
+            destroys.fetch_add(1, Ordering::SeqCst);
+        })
+        .unwrap();
+    }
+
+    assert_eq!(inits.load(Ordering::SeqCst), 2);
+    assert_eq!(destroys.load(Ordering::SeqCst), 2);
+    assert_eq!(lc.count(), 0);
+}
+
+/// Coverage: `shutdown` with the count already at zero is an error (unbalanced call).
+#[test]
+fn shutdown_when_idle_is_error() {
+    let lc: LibraryLifecycle<State> = LibraryLifecycle::new();
+    assert!(lc.shutdown(|_| ()).is_err());
+}
+
+/// Coverage: `with_state` before any `startup` (and after the matching `shutdown`) is an error
+/// because there is no active state.
+#[test]
+fn with_state_when_not_active_is_error() {
+    let lc: LibraryLifecycle<State> = LibraryLifecycle::new();
+    assert!(lc.with_state(|_s| ()).is_err());
+
+    lc.startup(|| -> Result<State, TestErr> { Ok(State { value: 5 }) })
+        .unwrap();
+    lc.shutdown(|_| ()).unwrap();
+    assert!(lc.with_state(|_s| ()).is_err());
+}
+
+/// Coverage: a failing init closure leaves the count at zero and the state absent, and the error is
+/// propagated (type-erased into `Error::Init`).
+#[test]
+fn init_failure_keeps_count_zero_and_propagates_error() {
+    let lc: LibraryLifecycle<State> = LibraryLifecycle::new();
+    let r = lc.startup(|| -> Result<State, TestErr> { Err(TestErr::Boom) });
+    assert!(r.is_err());
+    assert_eq!(lc.count(), 0);
+    // State is absent, so accessing it errors.
+    assert!(lc.with_state(|_s| ()).is_err());
+}
+
+/// Coverage: `with_state` reads the stored state during an active lifecycle.
+#[test]
+fn with_state_reads_active_state() {
+    let lc: LibraryLifecycle<State> = LibraryLifecycle::new();
+    lc.startup(|| -> Result<State, TestErr> { Ok(State { value: 99 }) })
+        .unwrap();
+
+    let observed = lc.with_state(|s| s.value).unwrap();
+    assert_eq!(observed, 99);
+
+    lc.shutdown(|_| ()).unwrap();
+}