Add AsyncIter and test for it

src/async_iter.rs

@@ -0,0 +1,57 @@
+use async_trait::async_trait;
+use futures::stream::BoxStream;
+use futures::{stream };
+
+#[async_trait]
+trait AsyncIter {
+    type Item: Sized;
+    async fn next(&mut self) -> Option<Self::Item>;
+
+    fn into_stream(self) -> BoxStream<'static, Self::Item>
+    where
+        Self: Sized + Send + 'static,
+    {
+        async fn helper<I>(mut iter: I) -> Option<(I::Item, I)>
+        where
+            I: AsyncIter,
+        {
+            let value = iter.next().await?;
+            Some((value, iter))
+        }
+        Box::pin(stream::unfold(self, helper))
+    }
+}
+
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use futures::StreamExt;
+    use futures::executor;
+
+    struct Numbers(usize);
+    impl Numbers {
+        fn new() -> Self {
+            Numbers(0)
+        }
+    }
+
+    #[async_trait]
+    impl AsyncIter for Numbers {
+        type Item = usize;
+
+        async fn next(&mut self) -> Option<Self::Item> {
+            self.0 = self.0.checked_add(1)?;
+            Some(self.0)
+        }
+    }
+    #[test]
+    fn test_numbers() {
+        let a = async {
+            let vec1: Vec<_> = Numbers::new().into_stream().take(10).collect().await;
+            let vec2: Vec<_> = (1..=10).into_iter().collect();
+            assert_eq!(vec1, vec2);
+        };
+        executor::block_on(a);
+    }
+}

src/main.rs

@@ -1,3 +1,4 @@
+mod async_iter;
 mod config;
 mod output;
 mod tile;

src/tiles/time.rs

@@ -49,7 +49,7 @@ impl Stream for TimeStream {
     type Item = Result<Block, Box<dyn Error + Send + Sync>>;
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
         let project = Pin::as_mut(&mut self).project();
-        ready!(Future::poll(project.delay, cx));
+        let () = ready!(Future::poll(project.delay, cx));
 
         let now = Local::now();
         Pin::as_mut(&mut self)