[red-knot]: Implement HasTy for Alias (#11971)

crates/red_knot_python_semantic/src/semantic_model.rs

@@ -163,6 +163,18 @@ impl HasTy for StmtClassDef {
     }
 }
 
+impl HasTy for ast::Alias {
+    fn ty<'db>(&self, model: &SemanticModel<'db>) -> Type<'db> {
+        let index = semantic_index(model.db, model.file);
+        let definition = index.definition(self);
+
+        let scope = definition.scope(model.db).to_scope_id(model.db, model.file);
+        let types = infer_types(model.db, scope);
+
+        types.definition_ty(definition)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use red_knot_module_resolver::{set_module_resolution_settings, ModuleResolutionSettings};
@@ -226,4 +238,26 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn alias_ty() -> anyhow::Result<()> {
+        let db = setup_db();
+
+        db.memory_file_system().write_files([
+            ("/src/foo.py", "class Test: pass"),
+            ("/src/bar.py", "from foo import Test"),
+        ])?;
+        let bar = system_path_to_file(&db, "/src/bar.py").unwrap();
+
+        let ast = parsed_module(&db, bar);
+
+        let import = ast.suite()[0].as_import_from_stmt().unwrap();
+        let alias = &import.names[0];
+        let model = SemanticModel::new(&db, bar);
+        let ty = alias.ty(&model);
+
+        assert!(matches!(ty, Type::Class(_)));
+
+        Ok(())
+    }
 }