coverage: Migrate tests/run-coverage into tests/coverage

tests/coverage/yield.rs

@@ -0,0 +1,37 @@
+#![feature(coroutines, coroutine_trait)]
+#![allow(unused_assignments)]
+
+use std::ops::{Coroutine, CoroutineState};
+use std::pin::Pin;
+
+fn main() {
+    let mut coroutine = || {
+        yield 1;
+        return "foo";
+    };
+
+    match Pin::new(&mut coroutine).resume(()) {
+        CoroutineState::Yielded(1) => {}
+        _ => panic!("unexpected value from resume"),
+    }
+    match Pin::new(&mut coroutine).resume(()) {
+        CoroutineState::Complete("foo") => {}
+        _ => panic!("unexpected value from resume"),
+    }
+
+    let mut coroutine = || {
+        yield 1;
+        yield 2;
+        yield 3;
+        return "foo";
+    };
+
+    match Pin::new(&mut coroutine).resume(()) {
+        CoroutineState::Yielded(1) => {}
+        _ => panic!("unexpected value from resume"),
+    }
+    match Pin::new(&mut coroutine).resume(()) {
+        CoroutineState::Yielded(2) => {}
+        _ => panic!("unexpected value from resume"),
+    }
+}