Validate custom executor is passed if needed

Author: t-moe

macros/src/attributes/tests/parse.rs

@@ -66,6 +66,18 @@ impl Input {
             validate_argument_type(test, expected_arg_type)?;
         }
 
+        // Validate a custom executor is provided if needed and at least one test/init is async
+        if cfg!(feature = "external-executor") && macro_args.executor.is_none() {
+            if tests.iter().any(|test| test.asyncness)
+                || init.as_ref().map_or(false, |i| i.asyncness)
+            {
+                return Err(parse::Error::new(
+                    proc_macro2::Span::call_site(),
+                    "async test/init func requires that an executor is provided via `#[embedded_test::tests(executor = ...)] because the feature `external-executor` is enabled",
+                ));
+            }
+        }
+
         Ok(Self {
             module_name: module.ident.to_string(),
             macro_args,

tests-build/cases/fail/embassy_no_executor_passed_but_needed_for_init.rs

@@ -0,0 +1,29 @@
+/*
+```cargo
+[dependencies]
+embassy-executor = { version = "0.7", features = ["arch-riscv32"] }
+embedded-test = { path = "../../..", features = ["embassy", "external-executor"] }
+
+[lib]
+harness = false
+```
+ */
+
+#![no_std]
+#![no_main]
+
+#[cfg(test)]
+#[embedded_test::tests]
+mod tests {
+    struct Context;
+
+    #[init]
+    async fn async_init() -> Context {
+        Context
+    }
+
+    #[test]
+    fn takes_state(_state: Context) {
+        assert!(true)
+    }
+}

tests-build/cases/fail/embassy_no_executor_passed_but_needed_for_init.stderr

@@ -0,0 +1 @@
+error: async test/init func requires that an executor is provided via `#[embedded_test::tests(executor = ...)] because the feature `external-executor` is enabled

tests-build/cases/fail/embassy_no_executor_passed_but_needed_for_test.rs

@@ -0,0 +1,29 @@
+/*
+```cargo
+[dependencies]
+embassy-executor = { version = "0.7", features = ["arch-riscv32"] }
+embedded-test = { path = "../../..", features = ["embassy", "external-executor"] }
+
+[lib]
+harness = false
+```
+ */
+
+#![no_std]
+#![no_main]
+
+#[cfg(test)]
+#[embedded_test::tests]
+mod tests {
+    struct Context;
+
+    #[init]
+    fn sync_init() -> Context {
+        Context
+    }
+
+    #[test]
+    async fn takes_state(_state: Context) {
+        assert!(true)
+    }
+}

tests-build/cases/fail/embassy_no_executor_passed_but_needed_for_test.stderr

@@ -0,0 +1 @@
+error: async test/init func requires that an executor is provided via `#[embedded_test::tests(executor = ...)] because the feature `external-executor` is enabled