[red-knot] Add walk_directories to System (#12297)

crates/red_knot/Cargo.toml

@@ -15,7 +15,7 @@ license.workspace = true
 red_knot_module_resolver = { workspace = true }
 red_knot_python_semantic = { workspace = true }
 
-ruff_db = { workspace = true }
+ruff_db = { workspace = true, features = ["os"] }
 ruff_python_ast = { workspace = true }
 
 anyhow = { workspace = true }

crates/red_knot_module_resolver/Cargo.toml

@@ -28,6 +28,8 @@ walkdir = { workspace = true }
 zip = { workspace = true }
 
 [dev-dependencies]
+ruff_db = { workspace = true, features = ["os"] }
+
 anyhow = { workspace = true }
 insta = { workspace = true }
 tempfile = { workspace = true }

crates/red_knot_module_resolver/src/resolver.rs

@@ -881,7 +881,7 @@ mod tests {
 
         let temp_dir = tempfile::tempdir()?;
         let root = SystemPath::from_std_path(temp_dir.path()).unwrap();
-        db.use_os_system(OsSystem::new(root));
+        db.use_system(OsSystem::new(root));
 
         let src = root.join("src");
         let site_packages = root.join("site-packages");

crates/ruff_db/Cargo.toml

@@ -20,6 +20,7 @@ camino = { workspace = true }
 countme = { workspace = true }
 dashmap = { workspace = true }
 filetime = { workspace = true }
+ignore = { workspace = true, optional = true }
 salsa = { workspace = true }
 tracing = { workspace = true }
 rustc-hash = { workspace = true }
@@ -28,3 +29,6 @@ zip = { workspace = true }
 [dev-dependencies]
 insta = { workspace = true }
 tempfile = { workspace = true }
+
+[features]
+os = ["ignore"]

crates/ruff_db/src/system.rs

@@ -1,15 +1,21 @@
+use std::fmt::Debug;
+
 pub use memory_fs::MemoryFileSystem;
+#[cfg(feature = "os")]
 pub use os::OsSystem;
 pub use test::{DbWithTestSystem, TestSystem};
+use walk_directory::WalkDirectoryBuilder;
 
 use crate::file_revision::FileRevision;
 
 pub use self::path::{SystemPath, SystemPathBuf};
 
 mod memory_fs;
+#[cfg(feature = "os")]
 mod os;
 mod path;
 mod test;
+pub mod walk_directory;
 
 pub type Result<T> = std::io::Result<T>;
 
@@ -27,7 +33,7 @@ pub type Result<T> = std::io::Result<T>;
 ///    * File watching isn't supported.
 ///
 /// Abstracting the system also enables tests to use a more efficient in-memory file system.
-pub trait System {
+pub trait System: Debug {
     /// Reads the metadata of the file or directory at `path`.
     fn path_metadata(&self, path: &SystemPath) -> Result<Metadata>;
 
@@ -82,6 +88,12 @@ pub trait System {
         path: &SystemPath,
     ) -> Result<Box<dyn Iterator<Item = Result<DirectoryEntry>> + 'a>>;
 
+    /// Recursively walks the content of `path`.
+    ///
+    /// It is allowed to pass a `path` that points to a file. In this case, the walker
+    /// yields a single entry for that file.
+    fn walk_directory(&self, path: &SystemPath) -> WalkDirectoryBuilder;
+
     fn as_any(&self) -> &dyn std::any::Any;
 }
 
@@ -127,28 +139,22 @@ impl FileType {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, PartialEq, Eq)]
 pub struct DirectoryEntry {
     path: SystemPathBuf,
-    file_type: Result<FileType>,
+    file_type: FileType,
 }
 
 impl DirectoryEntry {
-    pub fn new(path: SystemPathBuf, file_type: Result<FileType>) -> Self {
+    pub fn new(path: SystemPathBuf, file_type: FileType) -> Self {
         Self { path, file_type }
     }
 
     pub fn path(&self) -> &SystemPath {
         &self.path
     }
 
-    pub fn file_type(&self) -> &Result<FileType> {
-        &self.file_type
-    }
-}
-
-impl PartialEq for DirectoryEntry {
-    fn eq(&self, other: &Self) -> bool {
-        self.path == other.path
+    pub fn file_type(&self) -> FileType {
+        self.file_type
     }
 }