Remove EventSink from TestContext to simplify it

This replaces the EventSink callbacks with simple channel senders.
This simplifies the TestContext a lot as that is much simpler to
handle.  It then also removes the special-casing of the LogSink since
it now is another even sender, only injected at the very start.

src/sql.rs

@@ -678,11 +678,12 @@ async fn prune_tombstones(sql: &Sql) -> Result<()> {
 }
 
 #[cfg(test)]
-mod test {
+mod tests {
+    use async_std::channel;
     use async_std::fs::File;
 
     use crate::config::Config;
-    use crate::{test_utils::TestContext, Event, EventType};
+    use crate::{test_utils::TestContext, EventType};
 
     use super::*;
 
@@ -743,18 +744,8 @@ mod test {
             .await
             .unwrap();
 
-        t.add_event_sink(move |event: Event| async move {
-            match event.typ {
-                EventType::Info(s) => assert!(
-                    !s.contains("Keeping new unreferenced file"),
-                    "File {} was almost deleted, only reason it was kept is that it was created recently (as the tests don't run for a long time)",
-                    s
-                ),
-                EventType::Error(s) => panic!("{}", s),
-                _ => {}
-            }
-        })
-        .await;
+        let (event_sink, event_source) = channel::unbounded();
+        t.add_event_sender(event_sink).await;
 
         let a = t.get_config(Config::Selfavatar).await.unwrap().unwrap();
         assert_eq!(avatar_bytes, &async_std::fs::read(&a).await.unwrap()[..]);
@@ -765,6 +756,18 @@ mod test {
 
         let a = t.get_config(Config::Selfavatar).await.unwrap().unwrap();
         assert_eq!(avatar_bytes, &async_std::fs::read(&a).await.unwrap()[..]);
+
+        while let Ok(event) = event_source.try_recv() {
+            match event.typ {
+                EventType::Info(s) => assert!(
+                    !s.contains("Keeping new unreferenced file"),
+                    "File {} was almost deleted, only reason it was kept is that it was created recently (as the tests don't run for a long time)",
+                    s
+                ),
+                EventType::Error(s) => panic!("{}", s),
+                _ => {}
+            }
+        }
     }
 
     /// Regression test.