Generate invariant-enforcing tests in stubgen adapters.

trustfall/src/lib.rs

@@ -47,8 +47,8 @@ pub mod provider {
 
     // Helpers for common operations when building adapters.
     pub use trustfall_core::interpreter::helpers::{
-        resolve_coercion_using_schema, resolve_coercion_with, resolve_neighbors_with,
-        resolve_property_with, resolve_typename,
+        check_adapter_invariants, resolve_coercion_using_schema, resolve_coercion_with,
+        resolve_neighbors_with, resolve_property_with, resolve_typename,
     };
     pub use trustfall_core::{accessor_property, field_property};
 

trustfall_stubgen/README.md

@@ -22,6 +22,7 @@ The generated Trustfall adapter stub has the following structure:
 | adapter/entrypoints.rs | contains the entry points where all queries must start |
 | adapter/properties.rs  | contains the property implementations                  |
 | adapter/edges.rs       | contains the edge implementations                      |
+| adapter/tests.rs       | contains test code                                     |
 
 See an example of
 [a generated adapter stub](https://github.com/obi1kenobi/trustfall/tree/main/trustfall_stubgen/test_data/expected_outputs/hackernews/adapter)

trustfall_stubgen/src/adapter_creator.rs

@@ -23,6 +23,7 @@ pub(super) fn make_adapter_file(
     };
 
     let adapter_defn = quote! {
+        #[non_exhaustive]
         #[derive(Debug)]
         pub struct Adapter {}
     };
@@ -45,6 +46,10 @@ pub(super) fn make_adapter_file(
             pub fn schema() -> &'static Schema {
                 SCHEMA.get_or_init(|| Schema::parse(Self::SCHEMA_TEXT).expect("not a valid schema"))
             }
+
+            pub fn new() -> Self {
+                Self {}
+            }
         }
     };
 

trustfall_stubgen/src/root.rs

@@ -10,6 +10,8 @@ use quote::quote;
 use regex::Regex;
 use trustfall::{Schema, SchemaAdapter, TryIntoStruct};
 
+use crate::util::parse_import;
+
 use super::{
     adapter_creator::make_adapter_file, edges_creator::make_edges_file,
     entrypoints_creator::make_entrypoints_file, properties_creator::make_properties_file,
@@ -25,6 +27,7 @@ use super::{
 /// - adapter/entrypoints.rs  contains the entry points where all queries must start
 /// - adapter/properties.rs   contains the property implementations
 /// - adapter/edges.rs        contains the edge implementations
+/// - adapter/tests.rs        contains test code
 ///
 /// # Example
 /// ```no_run
@@ -62,13 +65,13 @@ pub fn generate_rust_stub(schema: &str, target: &Path) -> anyhow::Result<()> {
         &mut stub.properties,
     );
     make_edges_file(&querying_schema, schema_adapter.clone(), &mut stub.edges);
-
     make_adapter_file(
         &querying_schema,
         schema_adapter.clone(),
         &mut stub.adapter_impl,
         entrypoint_match_arms,
     );
+    make_tests_file(&mut stub.tests);
 
     stub.write_to_directory(target)
 }
@@ -266,6 +269,7 @@ struct AdapterStub<'a> {
     entrypoints: RustFile,
     properties: RustFile,
     edges: RustFile,
+    tests: RustFile,
 }
 
 impl<'a> AdapterStub<'a> {
@@ -279,6 +283,10 @@ impl<'a> AdapterStub<'a> {
             mod properties;
             mod edges;
         });
+        mod_.top_level_items.push(quote! {
+            #[cfg(test)]
+            mod tests;
+        });
         mod_.top_level_items.push(quote! {
             pub use adapter_impl::Adapter;
             pub use vertex::Vertex;
@@ -292,6 +300,7 @@ impl<'a> AdapterStub<'a> {
             entrypoints: Default::default(),
             properties: Default::default(),
             edges: Default::default(),
+            tests: Default::default(),
         }
     }
 
@@ -328,10 +337,33 @@ impl<'a> AdapterStub<'a> {
         self.edges.write_to_file(path_buf.as_path())?;
         path_buf.pop();
 
+        path_buf.push("tests.rs");
+        self.tests.write_to_file(path_buf.as_path())?;
+        path_buf.pop();
+
         Ok(())
     }
 }
 
+fn make_tests_file(tests_file: &mut RustFile) {
+    tests_file.external_imports.insert(parse_import(
+        "trustfall::provider::check_adapter_invariants",
+    ));
+
+    tests_file
+        .internal_imports
+        .insert(parse_import("super::Adapter"));
+
+    tests_file.top_level_items.push(quote! {
+        #[test]
+        fn adapter_satisfies_trustfall_invariants() {
+            let adapter = Adapter::new();
+            let schema = Adapter::schema();
+            check_adapter_invariants(schema, adapter);
+        }
+    });
+}
+
 fn make_vertex_file(
     querying_schema: &Schema,
     adapter: Arc<SchemaAdapter<'_>>,
@@ -368,6 +400,7 @@ fn make_vertex_file(
     }
 
     let vertex = quote! {
+        #[non_exhaustive]
         #[derive(Debug, Clone, trustfall::provider::TrustfallEnumVertex)]
         pub enum Vertex {
             #variants

trustfall_stubgen/src/tests.rs

@@ -77,12 +77,11 @@ fn get_relevant_files_from_dir(path: &Path) -> BTreeMap<PathBuf, PathBuf> {
     let mut dir_glob = path.to_path_buf();
     dir_glob.push("**");
     dir_glob.push("*");
-    dbg!(&dir_glob);
 
     glob::glob(dir_glob.to_str().expect("failed to convert path to &str"))
         .expect("failed to list dir")
         .filter_map(|res| {
-            let pathbuf = dbg!(res.expect("failed to check file"));
+            let pathbuf = res.expect("failed to check file");
             if !pathbuf.is_file() {
                 return None;
             }

trustfall_stubgen/test_data/expected_outputs/hackernews/adapter/adapter_impl.rs

@@ -6,6 +6,7 @@ use super::vertex::Vertex;
 
 static SCHEMA: OnceLock<Schema> = OnceLock::new();
 
+#[non_exhaustive]
 #[derive(Debug)]
 pub struct Adapter {}
 
@@ -18,6 +19,10 @@ impl Adapter {
                 Schema::parse(Self::SCHEMA_TEXT).expect("not a valid schema")
             })
     }
+
+    pub fn new() -> Self {
+        Self {}
+    }
 }
 
 impl<'a> trustfall::provider::Adapter<'a> for Adapter {

trustfall_stubgen/test_data/expected_outputs/hackernews/adapter/mod.rs

@@ -4,5 +4,8 @@ mod entrypoints;
 mod properties;
 mod edges;
 
+#[cfg(test)]
+mod tests;
+
 pub use adapter_impl::Adapter;
 pub use vertex::Vertex;

trustfall_stubgen/test_data/expected_outputs/hackernews/adapter/tests.rs

@@ -0,0 +1,10 @@
+use trustfall::provider::check_adapter_invariants;
+
+use super::Adapter;
+
+#[test]
+fn adapter_satisfies_trustfall_invariants() {
+    let adapter = Adapter::new();
+    let schema = Adapter::schema();
+    check_adapter_invariants(schema, adapter);
+}

trustfall_stubgen/test_data/expected_outputs/hackernews/adapter/vertex.rs

@@ -1,3 +1,4 @@
+#[non_exhaustive]
 #[derive(Debug, Clone, trustfall::provider::TrustfallEnumVertex)]
 pub enum Vertex {
     Comment(()),