[red-knot] Use vendored typeshed stubs for stdlib module resolution (#…

…12224)

crates/red_knot_module_resolver/src/db.rs

@@ -25,8 +25,9 @@ pub(crate) mod tests {
     use salsa::DebugWithDb;
 
     use ruff_db::files::Files;
-    use ruff_db::system::TestSystem;
-    use ruff_db::system::{DbWithTestSystem, SystemPathBuf};
+    use ruff_db::system::{
+        DbWithTestSystem, MemoryFileSystem, SystemPath, SystemPathBuf, TestSystem,
+    };
     use ruff_db::vendored::VendoredFileSystem;
 
     use crate::resolver::{set_module_resolution_settings, RawModuleResolutionSettings};
@@ -130,9 +131,9 @@ pub(crate) mod tests {
     pub(crate) struct TestCaseBuilder {
         db: TestDb,
         src: SystemPathBuf,
-        custom_typeshed: SystemPathBuf,
         site_packages: SystemPathBuf,
         target_version: Option<TargetVersion>,
+        with_vendored_stubs: bool,
     }
 
     impl TestCaseBuilder {
@@ -142,31 +143,88 @@ pub(crate) mod tests {
             self
         }
 
-        pub(crate) fn build(self) -> TestCase {
+        #[must_use]
+        pub(crate) fn with_vendored_stubs_used(mut self) -> Self {
+            self.with_vendored_stubs = true;
+            self
+        }
+
+        fn create_mocked_typeshed(
+            typeshed_dir: &SystemPath,
+            fs: &MemoryFileSystem,
+        ) -> std::io::Result<()> {
+            static VERSIONS_DATA: &str = "\
+            asyncio: 3.8-               # 'Regular' package on py38+
+            asyncio.tasks: 3.9-3.11
+            collections: 3.9-           # 'Regular' package on py39+
+            functools: 3.8-
+            importlib: 3.9-             # Namespace package on py39+
+            xml: 3.8-3.8                # Namespace package on py38 only
+            ";
+
+            fs.create_directory_all(typeshed_dir)?;
+            fs.write_file(typeshed_dir.join("stdlib/VERSIONS"), VERSIONS_DATA)?;
+
+            // Regular package on py38+
+            fs.create_directory_all(typeshed_dir.join("stdlib/asyncio"))?;
+            fs.touch(typeshed_dir.join("stdlib/asyncio/__init__.pyi"))?;
+            fs.write_file(
+                typeshed_dir.join("stdlib/asyncio/tasks.pyi"),
+                "class Task: ...",
+            )?;
+
+            // Regular package on py39+
+            fs.create_directory_all(typeshed_dir.join("stdlib/collections"))?;
+            fs.touch(typeshed_dir.join("stdlib/collections/__init__.pyi"))?;
+
+            // Namespace package on py38 only
+            fs.create_directory_all(typeshed_dir.join("stdlib/xml"))?;
+            fs.touch(typeshed_dir.join("stdlib/xml/etree.pyi"))?;
+
+            // Namespace package on py39+
+            fs.create_directory_all(typeshed_dir.join("stdlib/importlib"))?;
+            fs.touch(typeshed_dir.join("stdlib/importlib/abc.pyi"))?;
+
+            fs.write_file(
+                typeshed_dir.join("stdlib/functools.pyi"),
+                "def update_wrapper(): ...",
+            )
+        }
+
+        pub(crate) fn build(self) -> std::io::Result<TestCase> {
             let TestCaseBuilder {
                 mut db,
                 src,
-                custom_typeshed,
+                with_vendored_stubs,
                 site_packages,
                 target_version,
             } = self;
 
+            let typeshed_dir = SystemPathBuf::from("/typeshed");
+
+            let custom_typeshed = if with_vendored_stubs {
+                None
+            } else {
+                Self::create_mocked_typeshed(&typeshed_dir, db.memory_file_system())?;
+                Some(typeshed_dir.clone())
+            };
+
             let settings = RawModuleResolutionSettings {
                 target_version: target_version.unwrap_or_default(),
                 extra_paths: vec![],
                 workspace_root: src.clone(),
-                custom_typeshed: Some(custom_typeshed.clone()),
+                custom_typeshed: custom_typeshed.clone(),
                 site_packages: Some(site_packages.clone()),
             };
 
             set_module_resolution_settings(&mut db, settings);
 
-            TestCase {
+            Ok(TestCase {
                 db,
-                src,
-                custom_typeshed,
-                site_packages,
-            }
+                src: src.clone(),
+                custom_typeshed: typeshed_dir,
+                site_packages: site_packages.clone(),
+            })
         }
     }
 
@@ -178,57 +236,20 @@ pub(crate) mod tests {
     }
 
     pub(crate) fn create_resolver_builder() -> std::io::Result<TestCaseBuilder> {
-        static VERSIONS_DATA: &str = "\
-        asyncio: 3.8-               # 'Regular' package on py38+
-        asyncio.tasks: 3.9-3.11
-        collections: 3.9-           # 'Regular' package on py39+
-        functools: 3.8-
-        importlib: 3.9-             # Namespace package on py39+
-        xml: 3.8-3.8                # Namespace package on py38 only
-        ";
-
         let db = TestDb::new();
 
         let src = SystemPathBuf::from("/src");
         let site_packages = SystemPathBuf::from("/site_packages");
-        let custom_typeshed = SystemPathBuf::from("/typeshed");
 
         let fs = db.memory_file_system();
 
         fs.create_directory_all(&src)?;
         fs.create_directory_all(&site_packages)?;
-        fs.create_directory_all(&custom_typeshed)?;
-        fs.write_file(custom_typeshed.join("stdlib/VERSIONS"), VERSIONS_DATA)?;
-
-        // Regular package on py38+
-        fs.create_directory_all(custom_typeshed.join("stdlib/asyncio"))?;
-        fs.touch(custom_typeshed.join("stdlib/asyncio/__init__.pyi"))?;
-        fs.write_file(
-            custom_typeshed.join("stdlib/asyncio/tasks.pyi"),
-            "class Task: ...",
-        )?;
-
-        // Regular package on py39+
-        fs.create_directory_all(custom_typeshed.join("stdlib/collections"))?;
-        fs.touch(custom_typeshed.join("stdlib/collections/__init__.pyi"))?;
-
-        // Namespace package on py38 only
-        fs.create_directory_all(custom_typeshed.join("stdlib/xml"))?;
-        fs.touch(custom_typeshed.join("stdlib/xml/etree.pyi"))?;
-
-        // Namespace package on py39+
-        fs.create_directory_all(custom_typeshed.join("stdlib/importlib"))?;
-        fs.touch(custom_typeshed.join("stdlib/importlib/abc.pyi"))?;
-
-        fs.write_file(
-            custom_typeshed.join("stdlib/functools.pyi"),
-            "def update_wrapper(): ...",
-        )?;
 
         Ok(TestCaseBuilder {
             db,
             src,
-            custom_typeshed,
+            with_vendored_stubs: false,
             site_packages,
             target_version: None,
         })