Revert import changes in tests

After rust-lang#2216, these redundant imports are unneeded.
This reverts almost all of rust-lang#2101.
This also includes some minor cleanup of imports in tests.

Author: taiki-e

futures/tests/abortable.rs

@@ -1,9 +1,11 @@
+use futures::channel::oneshot;
+use futures::executor::block_on;
+use futures::future::{abortable, Aborted, FutureExt};
+use futures::task::{Context, Poll};
+use futures_test::task::new_count_waker;
+
 #[test]
 fn abortable_works() {
-    use futures::channel::oneshot;
-    use futures::future::{abortable, Aborted};
-    use futures::executor::block_on;
-
     let (_tx, a_rx) = oneshot::channel::<()>();
     let (abortable_rx, abort_handle) = abortable(a_rx);
 
@@ -13,11 +15,6 @@ fn abortable_works() {
 
 #[test]
 fn abortable_awakens() {
-    use futures::channel::oneshot;
-    use futures::future::{abortable, Aborted, FutureExt};
-    use futures::task::{Context, Poll};
-    use futures_test::task::new_count_waker;
-
     let (_tx, a_rx) = oneshot::channel::<()>();
     let (mut abortable_rx, abort_handle) = abortable(a_rx);
 
@@ -33,9 +30,6 @@ fn abortable_awakens() {
 
 #[test]
 fn abortable_resolves() {
-    use futures::channel::oneshot;
-    use futures::future::abortable;
-    use futures::executor::block_on;
     let (tx, a_rx) = oneshot::channel::<()>();
     let (abortable_rx, _abort_handle) = abortable(a_rx);
 

futures/tests/arc_wake.rs

@@ -1,69 +1,65 @@
-mod countingwaker {
-    use futures::task::{self, ArcWake, Waker};
-    use std::sync::{Arc, Mutex};
+use futures::task::{self, ArcWake, Waker};
+use std::panic;
+use std::sync::{Arc, Mutex};
 
-    struct CountingWaker {
-        nr_wake: Mutex<i32>,
-    }
+struct CountingWaker {
+    nr_wake: Mutex<i32>,
+}
 
-    impl CountingWaker {
-        fn new() -> Self {
-            Self {
-                nr_wake: Mutex::new(0),
-            }
+impl CountingWaker {
+    fn new() -> Self {
+        Self {
+            nr_wake: Mutex::new(0),
         }
+    }
 
-        fn wakes(&self) -> i32 {
-            *self.nr_wake.lock().unwrap()
-        }
+    fn wakes(&self) -> i32 {
+        *self.nr_wake.lock().unwrap()
     }
+}
 
-    impl ArcWake for CountingWaker {
-        fn wake_by_ref(arc_self: &Arc<Self>) {
-            let mut lock = arc_self.nr_wake.lock().unwrap();
-            *lock += 1;
-        }
+impl ArcWake for CountingWaker {
+    fn wake_by_ref(arc_self: &Arc<Self>) {
+        let mut lock = arc_self.nr_wake.lock().unwrap();
+        *lock += 1;
     }
+}
 
-    #[test]
-    fn create_from_arc() {
-        let some_w = Arc::new(CountingWaker::new());
+#[test]
+fn create_from_arc() {
+    let some_w = Arc::new(CountingWaker::new());
 
-        let w1: Waker = task::waker(some_w.clone());
-        assert_eq!(2, Arc::strong_count(&some_w));
-        w1.wake_by_ref();
-        assert_eq!(1, some_w.wakes());
+    let w1: Waker = task::waker(some_w.clone());
+    assert_eq!(2, Arc::strong_count(&some_w));
+    w1.wake_by_ref();
+    assert_eq!(1, some_w.wakes());
 
-        let w2 = w1.clone();
-        assert_eq!(3, Arc::strong_count(&some_w));
+    let w2 = w1.clone();
+    assert_eq!(3, Arc::strong_count(&some_w));
 
-        w2.wake_by_ref();
-        assert_eq!(2, some_w.wakes());
+    w2.wake_by_ref();
+    assert_eq!(2, some_w.wakes());
 
-        drop(w2);
-        assert_eq!(2, Arc::strong_count(&some_w));
-        drop(w1);
-        assert_eq!(1, Arc::strong_count(&some_w));
-    }
+    drop(w2);
+    assert_eq!(2, Arc::strong_count(&some_w));
+    drop(w1);
+    assert_eq!(1, Arc::strong_count(&some_w));
+}
 
-    #[test]
-    fn ref_wake_same() {
-        let some_w = Arc::new(CountingWaker::new());
+#[test]
+fn ref_wake_same() {
+    let some_w = Arc::new(CountingWaker::new());
 
-        let w1: Waker = task::waker(some_w.clone());
-        let w2 = task::waker_ref(&some_w);
-        let w3 = w2.clone();
+    let w1: Waker = task::waker(some_w.clone());
+    let w2 = task::waker_ref(&some_w);
+    let w3 = w2.clone();
 
-        assert!(w1.will_wake(&w2));
-        assert!(w2.will_wake(&w3));
-    }
+    assert!(w1.will_wake(&w2));
+    assert!(w2.will_wake(&w3));
 }
 
 #[test]
 fn proper_refcount_on_wake_panic() {
-    use futures::task::{self, ArcWake, Waker};
-    use std::sync::Arc;
-
     struct PanicWaker;
 
     impl ArcWake for PanicWaker {
@@ -75,7 +71,13 @@ fn proper_refcount_on_wake_panic() {
     let some_w = Arc::new(PanicWaker);
 
     let w1: Waker = task::waker(some_w.clone());
-    assert_eq!("WAKE UP", *std::panic::catch_unwind(|| w1.wake_by_ref()).unwrap_err().downcast::<&str>().unwrap());
+    assert_eq!(
+        "WAKE UP",
+        *panic::catch_unwind(|| w1.wake_by_ref())
+            .unwrap_err()
+            .downcast::<&str>()
+            .unwrap()
+    );
     assert_eq!(2, Arc::strong_count(&some_w)); // some_w + w1
     drop(w1);
     assert_eq!(1, Arc::strong_count(&some_w)); // some_w