Add tests for periodic reader from various RT combinations (#2147)

These tests should help with testing #2142

opentelemetry-sdk/src/metrics/periodic_reader.rs

@@ -381,29 +381,41 @@ mod tests {
     use std::sync::mpsc;
 
     #[test]
-    fn collection_triggered_by_interval() {
-        // Arrange
-        let interval = std::time::Duration::from_millis(1);
-        let exporter = InMemoryMetricsExporter::default();
-        let reader = PeriodicReader::builder(exporter.clone(), runtime::TokioCurrentThread)
-            .with_interval(interval)
-            .build();
-        let (sender, receiver) = mpsc::channel();
+    fn collection_triggered_by_interval_tokio_current() {
+        collection_triggered_by_interval_helper(runtime::TokioCurrentThread);
+    }
 
-        // Act
-        let meter_provider = SdkMeterProvider::builder().with_reader(reader).build();
-        let meter = meter_provider.meter("test");
-        let _counter = meter
-            .u64_observable_counter("testcounter")
-            .with_callback(move |_| {
-                sender.send(()).expect("channel should still be open");
-            })
-            .init();
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn collection_triggered_by_interval_from_tokio_multi_one_thread_on_runtime_tokio() {
+        collection_triggered_by_interval_helper(runtime::Tokio);
+    }
 
-        // Assert
-        receiver
-            .recv()
-            .expect("message should be available in channel, indicating a collection occurred");
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    async fn collection_triggered_by_interval_from_tokio_multi_two_thread_on_runtime_tokio() {
+        collection_triggered_by_interval_helper(runtime::Tokio);
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
+    async fn collection_triggered_by_interval_from_tokio_multi_one_thread_on_runtime_tokio_current()
+    {
+        collection_triggered_by_interval_helper(runtime::TokioCurrentThread);
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    async fn collection_triggered_by_interval_from_tokio_multi_two_thread_on_runtime_tokio_current()
+    {
+        collection_triggered_by_interval_helper(runtime::TokioCurrentThread);
+    }
+
+    #[tokio::test(flavor = "current_thread")]
+    #[ignore = "See issue https://github.com/open-telemetry/opentelemetry-rust/issues/2056"]
+    async fn collection_triggered_by_interval_from_tokio_current_on_runtime_tokio() {
+        collection_triggered_by_interval_helper(runtime::Tokio);
+    }
+
+    #[tokio::test(flavor = "current_thread")]
+    async fn collection_triggered_by_interval_from_tokio_current_on_runtime_tokio_current() {
+        collection_triggered_by_interval_helper(runtime::TokioCurrentThread);
     }
 
     #[test]
@@ -424,4 +436,31 @@ mod tests {
             matches!(result.unwrap_err(), MetricsError::Other(err) if err == "reader is not registered")
         );
     }
+
+    fn collection_triggered_by_interval_helper<RT>(runtime: RT)
+    where
+        RT: crate::runtime::Runtime,
+    {
+        let interval = std::time::Duration::from_millis(1);
+        let exporter = InMemoryMetricsExporter::default();
+        let reader = PeriodicReader::builder(exporter.clone(), runtime)
+            .with_interval(interval)
+            .build();
+        let (sender, receiver) = mpsc::channel();
+
+        // Act
+        let meter_provider = SdkMeterProvider::builder().with_reader(reader).build();
+        let meter = meter_provider.meter("test");
+        let _counter = meter
+            .u64_observable_counter("testcounter")
+            .with_callback(move |_| {
+                sender.send(()).expect("channel should still be open");
+            })
+            .init();
+
+        // Assert
+        receiver
+            .recv()
+            .expect("message should be available in channel, indicating a collection occurred");
+    }
 }