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

tests/coverage/coroutine.rs

@@ -0,0 +1,30 @@
+#![feature(coroutines, coroutine_trait)]
+
+use std::ops::{Coroutine, CoroutineState};
+use std::pin::Pin;
+
+// The following implementation of a function called from a `yield` statement
+// (apparently requiring the Result and the `String` type or constructor)
+// creates conditions where the `coroutine::StateTransform` MIR transform will
+// drop all `Counter` `Coverage` statements from a MIR. `simplify.rs` has logic
+// to handle this condition, and still report dead block coverage.
+fn get_u32(val: bool) -> Result<u32, String> {
+    if val { Ok(1) } else { Err(String::from("some error")) }
+}
+
+fn main() {
+    let is_true = std::env::args().len() == 1;
+    let mut coroutine = || {
+        yield get_u32(is_true);
+        return "foo";
+    };
+
+    match Pin::new(&mut coroutine).resume(()) {
+        CoroutineState::Yielded(Ok(1)) => {}
+        _ => panic!("unexpected return from resume"),
+    }
+    match Pin::new(&mut coroutine).resume(()) {
+        CoroutineState::Complete("foo") => {}
+        _ => panic!("unexpected return from resume"),
+    }
+}