add trybuild compile tests

actix-macros/tests/trybuild.rs

@@ -0,0 +1,9 @@
+#[test]
+fn compile_macros() {
+    let t = trybuild::TestCases::new();
+    t.pass("tests/trybuild/main-01-basic.rs");
+    t.compile_fail("tests/trybuild/main-02-only-async.rs");
+
+    t.pass("tests/trybuild/test-01-basic.rs");
+    t.pass("tests/trybuild/test-02-keep-attrs.rs");
+}

actix-macros/tests/trybuild/main-01-basic.rs

@@ -0,0 +1,4 @@
+#[actix_rt::main]
+async fn main() {
+    println!("Hello world");
+}

actix-macros/tests/trybuild/main-02-only-async.rs

@@ -0,0 +1,4 @@
+#[actix_rt::main]
+fn main() {
+    futures::future::ready(()).await
+}

actix-macros/tests/trybuild/main-02-only-async.stderr

@@ -0,0 +1,14 @@
+error: only async fn is supported
+ --> $DIR/main-02-only-async.rs:2:1
+  |
+2 | fn main() {
+  | ^^
+
+error[E0601]: `main` function not found in crate `$CRATE`
+ --> $DIR/main-02-only-async.rs:1:1
+  |
+1 | / #[actix_rt::main]
+2 | | fn main() {
+3 | |     futures::future::ready(()).await
+4 | | }
+  | |_^ consider adding a `main` function to `$DIR/tests/trybuild/main-02-only-async.rs`

actix-macros/tests/trybuild/test-01-basic.rs

@@ -0,0 +1,6 @@
+#[actix_rt::test]
+async fn my_test() {
+    assert!(true);
+}
+
+fn main() {}

actix-macros/tests/trybuild/test-02-keep-attrs.rs

@@ -0,0 +1,7 @@
+#[actix_rt::test]
+#[should_panic]
+async fn my_test() {
+    todo!()
+}
+
+fn main() {}