api: Replace ruma_api! compile-time path check with a test

crates/ruma-common/src/api/metadata.rs

@@ -124,6 +124,13 @@ impl Metadata {
 
         Ok(res)
     }
+
+    // Used for generated `#[test]`s
+    #[doc(hidden)]
+    pub fn _path_parameters(&self) -> Vec<&'static str> {
+        let path = self.history.all_paths().next().unwrap();
+        path.split('/').filter_map(|segment| segment.strip_prefix(':')).collect()
+    }
 }
 
 /// The complete history of this endpoint as far as Ruma knows, together with all variants on

crates/ruma-macros/src/api.rs

@@ -12,12 +12,7 @@ use syn::{
     Attribute, Field, Token, Type,
 };
 
-use self::{
-    api_metadata::Metadata,
-    api_request::Request,
-    api_response::Response,
-    request::{RequestField, RequestFieldKind},
-};
+use self::{api_metadata::Metadata, api_request::Request, api_response::Response};
 use crate::util::import_ruma_common;
 
 mod api_metadata;
@@ -56,7 +51,6 @@ pub struct Api {
 impl Api {
     pub fn expand_all(self) -> TokenStream {
         let maybe_feature_error = ensure_feature_presence().map(syn::Error::to_compile_error);
-        let maybe_path_error = self.check_paths().err().map(syn::Error::into_compile_error);
 
         let ruma_common = import_ruma_common();
 
@@ -80,7 +74,6 @@ impl Api {
 
         quote! {
             #maybe_feature_error
-            #maybe_path_error
 
             // For some reason inlining the expression causes issues with macro parsing
             const _RUMA_API_VERSION_HISTORY: #ruma_common::api::VersionHistory = #history;
@@ -102,39 +95,6 @@ impl Api {
             type _SilenceUnusedError = #error_ty;
         }
     }
-
-    fn check_paths(&self) -> syn::Result<()> {
-        let mut path_iter = self.metadata.history.entries.iter().filter_map(|entry| entry.path());
-
-        let path = path_iter.next().ok_or_else(|| {
-            syn::Error::new(Span::call_site(), "at least one path metadata field must be set")
-        })?;
-        let path_args = path.args();
-
-        if let Some(req) = &self.request {
-            let path_field_names: Vec<_> = req
-                .fields
-                .iter()
-                .cloned()
-                .filter_map(|f| match RequestField::try_from(f) {
-                    Ok(RequestField { kind: RequestFieldKind::Path, inner }) => {
-                        Some(Ok(inner.ident.unwrap().to_string()))
-                    }
-                    Ok(_) => None,
-                    Err(e) => Some(Err(e)),
-                })
-                .collect::<syn::Result<_>>()?;
-
-            if path_args != path_field_names {
-                return Err(syn::Error::new_spanned(
-                    req.request_kw,
-                    "path fields must be in the same order as they appear in the path segments",
-                ));
-            }
-        }
-
-        Ok(())
-    }
 }
 
 impl Parse for Api {

crates/ruma-macros/src/api/api_metadata.rs

@@ -389,17 +389,6 @@ pub enum HistoryEntry {
     Removed { version: MatrixVersionLiteral },
 }
 
-impl HistoryEntry {
-    pub(super) fn path(&self) -> Option<&EndpointPath> {
-        Some(match self {
-            HistoryEntry::Stable { version: _, path } => path,
-            HistoryEntry::Unstable { path } => path,
-
-            _ => return None,
-        })
-    }
-}
-
 #[derive(Clone, Debug, PartialEq)]
 pub struct EndpointPath(LitStr);
 
@@ -407,10 +396,6 @@ impl EndpointPath {
     pub fn value(&self) -> String {
         self.0.value()
     }
-
-    pub fn args(&self) -> Vec<String> {
-        self.value().split('/').filter_map(|s| s.strip_prefix(':')).map(String::from).collect()
-    }
 }
 
 impl Parse for EndpointPath {

crates/ruma-macros/src/api/request.rs

@@ -238,7 +238,7 @@ impl Request {
         }
     }
 
-    pub(super) fn check(&self, ruma_common: &TokenStream) -> syn::Result<Option<TokenStream>> {
+    pub(super) fn check(&self, ruma_common: &TokenStream) -> syn::Result<TokenStream> {
         let http = quote! { #ruma_common::exports::http };
 
         // TODO: highlight problematic fields
@@ -297,8 +297,21 @@ impl Request {
             ));
         }
 
-        Ok((has_body_fields || has_newtype_body_field).then(|| {
-            quote! {
+        let path_fields = self.path_fields().map(|f| f.ident.as_ref().unwrap().to_string());
+        let mut tests = quote! {
+            #[::std::prelude::v1::test]
+            fn path_parameters() {
+                let path_params = METADATA._path_parameters();
+                let request_path_fields: &[&::std::primitive::str] = &[#(#path_fields),*];
+                ::std::assert_eq!(
+                    path_params, request_path_fields,
+                    "Path parameters must match the `Request`'s `#[ruma_api(path)]` fields"
+                );
+            }
+        };
+
+        if has_body_fields || has_newtype_body_field {
+            tests.extend(quote! {
                 #[::std::prelude::v1::test]
                 fn request_is_not_get() {
                     ::std::assert_ne!(
@@ -306,8 +319,10 @@ impl Request {
                         "GET endpoints can't have body fields",
                     );
                 }
+            });
         }
-        }))
+
+        Ok(tests)
     }
 }