added unit test to `multithreading`

src/multithreading/mod.rs

@@ -346,3 +346,54 @@ fn execute<F, T>(
         result
     }));
 }
+
+#[cfg(test)]
+mod tests {
+    use std::time::Duration;
+
+    use super::*;
+
+    #[test]
+    fn test_thread_pool() {
+        // auto determine the amount of threads to use
+        let mut pool = ThreadPool::new();
+
+        // launch 4 jobs to run on our pool
+        for i in 0..4 {
+            pool.enqueue(move || (0..=i).sum::<usize>());
+        }
+
+        // wait for the threads to finish and sum their results
+        let sum = pool
+            .join_all()
+            .into_iter()
+            .map(|r| r.unwrap())
+            .sum::<usize>();
+
+        assert_eq!(sum, 10);
+    }
+
+    #[test]
+    fn test_drop_stalled() {
+        // auto determine the amount of threads to use
+        let mut pool = ThreadPool::with_threads(NonZeroUsize::new(1).unwrap());
+
+        // launch 2 jobs: 1 will immediately return, the other one will sleep for 20 seconds
+        for i in 0..1 {
+            pool.enqueue(move || {
+                thread::sleep(Duration::from_secs(i * 20));
+                i
+            });
+        }
+
+        // wait 10 secs
+        thread::sleep(Duration::from_secs(2));
+        // discard job that should still run
+        pool.discard_stalled();
+
+        // wait for the threads to finish and sum their results
+        let sum = pool.join_all().into_iter().map(|r| r.unwrap()).sum::<u64>();
+
+        assert_eq!(sum, 0);
+    }
+}