Implement first trybuild tests

and use a dedicated InvalidEvent constructor fn in EventContent derives

.gitignore

@@ -1,2 +1,5 @@
 Cargo.lock
 target
+
+# trybuild generates a `wip` folder when creating or updating a test
+wip

Cargo.toml

@@ -26,6 +26,7 @@ strum = { version = "0.18.0", features = ["derive"] }
 maplit = "1.0.2"
 matches = "0.1.8"
 ruma-identifiers = { version = "0.16.2", features = ["rand"] }
+trybuild = "1.0.27"
 
 [workspace]
 members = [

ruma-events-macros/src/event_content.rs

@@ -58,10 +58,9 @@ fn expand_room_event(input: DeriveInput) -> syn::Result<TokenStream> {
                 content: Box<::serde_json::value::RawValue>
             ) -> Result<Self, ::ruma_events::InvalidEvent> {
                 if ev_type != #event_type {
-                    return Err(::ruma_events::InvalidEvent {
-                        kind: ::ruma_events::error::InvalidEventKind::Deserialization,
-                        message: format!("expected `{}` found {}", #event_type, ev_type),
-                    });
+                    return Err(
+                        ::ruma_events::InvalidEvent::wrong_event_type(#event_type, ev_type)
+                    );
                 }
 
                 let ev_json = ::ruma_events::EventJson::from(content);

src/error.rs

@@ -11,17 +11,32 @@ use std::{
 /// message and a flag for which type of error was encountered.
 #[derive(Clone, Debug)]
 pub struct InvalidEvent {
+    /// A description of the error that occurred.
     pub(crate) message: String,
+    /// The kind of error that occurred.
     pub(crate) kind: InvalidEventKind,
 }
 
+/// The kind of error that occurred.
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
-pub enum InvalidEventKind {
+pub(crate) enum InvalidEventKind {
+    /// A deserialization error from malformed input.
     Deserialization,
+    /// An error occurred validating input according the the matrix spec.
     Validation,
 }
 
 impl InvalidEvent {
+    /// Constructor used in the event content macros.
+    ///
+    /// This has to be public to allow the macros to be used outside of ruma-events.
+    #[doc(hidden)]
+    pub fn wrong_event_type(expected: &str, found: &str) -> Self {
+        Self {
+            message: format!("expected `{}` found {}", expected, found),
+            kind: InvalidEventKind::Deserialization,
+        }
+    }
     /// A message describing why the event is invalid.
     pub fn message(&self) -> String {
         self.message.clone()

tests/event_content.rs

@@ -0,0 +1,7 @@
+#[test]
+fn ui() {
+    let t = trybuild::TestCases::new();
+    t.pass("tests/ui/01-sanity-check.rs");
+    t.compile_fail("tests/ui/02-no-event-type.rs");
+    t.compile_fail("tests/ui/03-invalid-event-type.rs");
+}

tests/ui/01-sanity-check.rs

@@ -0,0 +1,10 @@
+use ruma_events_macros::{FromRaw, StateEventContent};
+use serde::Serialize;
+
+#[derive(Clone, Debug, Serialize, FromRaw, StateEventContent)]
+#[ruma_event(type = "m.macro.test")]
+pub struct MacroTest {
+    pub url: String,
+}
+
+fn main() {}

tests/ui/02-no-event-type.rs

@@ -0,0 +1,9 @@
+use ruma_events_macros::{FromRaw, StateEventContent};
+use serde::Serialize;
+
+#[derive(Clone, Debug, Serialize, FromRaw, StateEventContent)]
+pub struct MacroTest {
+    pub url: String,
+}
+
+fn main() {}

tests/ui/02-no-event-type.stderr

@@ -0,0 +1,7 @@
+error: no event type attribute found, add `#[ruma_events(type = "any.room.event")]` below the event content derive
+ --> $DIR/02-no-event-type.rs:4:44
+  |
+4 | #[derive(Clone, Debug, Serialize, FromRaw, StateEventContent)]
+  |                                            ^^^^^^^^^^^^^^^^^
+  |
+  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

tests/ui/03-invalid-event-type.rs

@@ -0,0 +1,16 @@
+use ruma_events_macros::{FromRaw, StateEventContent};
+use serde::Serialize;
+
+#[derive(Clone, Debug, Serialize, FromRaw, StateEventContent)]
+#[not_ruma_event(type = "m.macro.test")]
+pub struct MacroTest {
+    pub test: String,
+}
+
+#[derive(Clone, Debug, Serialize, StateEventContent)]
+#[ruma_event(event = "m.macro.test")]
+pub struct MoreMacroTest {
+    pub test: String,
+}
+
+fn main() {}

tests/ui/03-invalid-event-type.stderr

@@ -0,0 +1,19 @@
+error: expected `type`
+  --> $DIR/03-invalid-event-type.rs:11:14
+   |
+11 | #[ruma_event(event = "m.macro.test")]
+   |              ^^^^^
+
+error: no event type attribute found, add `#[ruma_events(type = "any.room.event")]` below the event content derive
+ --> $DIR/03-invalid-event-type.rs:4:44
+  |
+4 | #[derive(Clone, Debug, Serialize, FromRaw, StateEventContent)]
+  |                                            ^^^^^^^^^^^^^^^^^
+  |
+  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: cannot find attribute `not_ruma_event` in this scope
+ --> $DIR/03-invalid-event-type.rs:5:3
+  |
+5 | #[not_ruma_event(type = "m.macro.test")]
+  |   ^^^^^^^^^^^^^^ help: a derive helper attribute with a similar name exists: `ruma_event`