4 files changed, 143 insertions, 1 deletions

diff --git a/.github/ci/test.sh b/.github/ci/test.sh
index af0f21c2a..e48d6e65b 100755
--- a/.github/ci/test.sh
+++ b/.github/ci/test.sh
@@ -15,6 +15,8 @@ export CARGO_NET_GIT_FETCH_WITH_CLI=true
 hashtime restore /ci/cache/filetime.json || true
 hashtime save /ci/cache/filetime.json
 
+MIRIFLAGS=-Zmiri-ignore-leaks cargo miri test --manifest-path ./embassy-executor/Cargo.toml --features nightly
+
 cargo test --manifest-path ./embassy-sync/Cargo.toml 
 cargo test --manifest-path ./embassy-embedded-hal/Cargo.toml 
 cargo test --manifest-path ./embassy-hal-internal/Cargo.toml 
diff --git a/embassy-executor/Cargo.toml b/embassy-executor/Cargo.toml
index 54ea1a548..f0e85a2c8 100644
--- a/embassy-executor/Cargo.toml
+++ b/embassy-executor/Cargo.toml
@@ -68,3 +68,6 @@ cortex-m = { version = "0.7.6", optional = true }
 # arch-wasm dependencies
 wasm-bindgen = { version = "0.2.82", optional = true }
 js-sys = { version = "0.3", optional = true }
+
+[dev-dependencies]
+critical-section = { version = "1.1", features = ["std"] }
diff --git a/embassy-executor/tests/test.rs b/embassy-executor/tests/test.rs
new file mode 100644
index 000000000..0dbd391e8
--- /dev/null
+++ b/embassy-executor/tests/test.rs
@@ -0,0 +1,137 @@
+#![cfg_attr(feature = "nightly", feature(type_alias_impl_trait))]
+
+use std::boxed::Box;
+use std::future::poll_fn;
+use std::sync::{Arc, Mutex};
+use std::task::Poll;
+
+use embassy_executor::raw::Executor;
+use embassy_executor::task;
+
+#[export_name = "__pender"]
+fn __pender(context: *mut ()) {
+    unsafe {
+        let trace = &*(context as *const Trace);
+        trace.push("pend");
+    }
+}
+
+#[derive(Clone)]
+struct Trace {
+    trace: Arc<Mutex<Vec<&'static str>>>,
+}
+
+impl Trace {
+    fn new() -> Self {
+        Self {
+            trace: Arc::new(Mutex::new(Vec::new())),
+        }
+    }
+    fn push(&self, value: &'static str) {
+        self.trace.lock().unwrap().push(value)
+    }
+
+    fn get(&self) -> Vec<&'static str> {
+        self.trace.lock().unwrap().clone()
+    }
+}
+
+fn setup() -> (&'static Executor, Trace) {
+    let trace = Trace::new();
+    let context = Box::leak(Box::new(trace.clone())) as *mut _ as *mut ();
+    let executor = &*Box::leak(Box::new(Executor::new(context)));
+    (executor, trace)
+}
+
+#[test]
+fn executor_noop() {
+    let (executor, trace) = setup();
+    unsafe { executor.poll() };
+    assert!(trace.get().is_empty())
+}
+
+#[test]
+fn executor_task() {
+    #[task]
+    async fn task1(trace: Trace) {
+        trace.push("poll task1")
+    }
+
+    let (executor, trace) = setup();
+    executor.spawner().spawn(task1(trace.clone())).unwrap();
+
+    unsafe { executor.poll() };
+    unsafe { executor.poll() };
+
+    assert_eq!(
+        trace.get(),
+        &[
+            "pend",       // spawning a task pends the executor
+            "poll task1", // poll only once.
+        ]
+    )
+}
+
+#[test]
+fn executor_task_self_wake() {
+    #[task]
+    async fn task1(trace: Trace) {
+        poll_fn(|cx| {
+            trace.push("poll task1");
+            cx.waker().wake_by_ref();
+            Poll::Pending
+        })
+        .await
+    }
+
+    let (executor, trace) = setup();
+    executor.spawner().spawn(task1(trace.clone())).unwrap();
+
+    unsafe { executor.poll() };
+    unsafe { executor.poll() };
+
+    assert_eq!(
+        trace.get(),
+        &[
+            "pend",       // spawning a task pends the executor
+            "poll task1", //
+            "pend",       // task self-wakes
+            "poll task1", //
+            "pend",       // task self-wakes
+        ]
+    )
+}
+
+#[test]
+fn executor_task_self_wake_twice() {
+    #[task]
+    async fn task1(trace: Trace) {
+        poll_fn(|cx| {
+            trace.push("poll task1");
+            cx.waker().wake_by_ref();
+            trace.push("poll task1 wake 2");
+            cx.waker().wake_by_ref();
+            Poll::Pending
+        })
+        .await
+    }
+
+    let (executor, trace) = setup();
+    executor.spawner().spawn(task1(trace.clone())).unwrap();
+
+    unsafe { executor.poll() };
+    unsafe { executor.poll() };
+
+    assert_eq!(
+        trace.get(),
+        &[
+            "pend",              // spawning a task pends the executor
+            "poll task1",        //
+            "pend",              // task self-wakes
+            "poll task1 wake 2", // task self-wakes again, shouldn't pend
+            "poll task1",        //
+            "pend",              // task self-wakes
+            "poll task1 wake 2", // task self-wakes again, shouldn't pend
+        ]
+    )
+}
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index 419c31085..11f53ee4a 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -2,7 +2,7 @@
 # https://rust-lang.github.io/rustup-components-history
 [toolchain]
 channel = "nightly-2023-11-01"
-components = [ "rust-src", "rustfmt", "llvm-tools" ]
+components = [ "rust-src", "rustfmt", "llvm-tools", "miri" ]
 targets = [
     "thumbv7em-none-eabi",
     "thumbv7m-none-eabi",