refactor(tvix/castore): add RootNode impl for BTreeMap, mv fs tests

cl/10378 did already move store/fs to castore/fs, but we kept the tests
in tvix-store, as they were populating a PathInfoService to make nodes
appear in the mount root.

Update these tests to now just insert root nodes into a BTreeMap, and
ensure we can use that as a RootNodes too.

Change-Id: Iad7d1ee4f9423eb6e3a1da33f433842c9ae0de1f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10410
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>

tvix/Cargo.lock

@@ -3244,7 +3244,6 @@ dependencies = [
  "data-encoding",
  "futures",
  "lazy_static",
- "libc",
  "nix-compat",
  "pin-project-lite",
  "prost",

tvix/Cargo.nix

@@ -10267,10 +10267,6 @@ rec {
           }
         ];
         devDependencies = [
-          {
-            name = "libc";
-            packageId = "libc";
-          }
           {
             name = "tempfile";
             packageId = "tempfile";

tvix/castore/src/fs/mod.rs

@@ -9,6 +9,9 @@ pub mod fuse;
 #[cfg(feature = "virtiofs")]
 pub mod virtiofs;
 
+#[cfg(test)]
+mod tests;
+
 use crate::proto as castorepb;
 use crate::{
     blobservice::{BlobReader, BlobService},

tvix/castore/src/fs/root_nodes.rs

@@ -1,6 +1,7 @@
-use std::pin::Pin;
+use std::{collections::BTreeMap, ops::Deref, pin::Pin};
 
 use crate::{proto::node::Node, Error};
+use bytes::Bytes;
 use futures::Stream;
 use tonic::async_trait;
 
@@ -14,5 +15,21 @@ pub trait RootNodes: Send + Sync {
 
     /// Lists all root CA nodes in the filesystem. An error can be returned
     /// in case listing is not allowed
-    fn list(&self) -> Pin<Box<dyn Stream<Item = Result<Node, Error>> + Send>>;
+    fn list(&self) -> Pin<Box<dyn Stream<Item = Result<Node, Error>> + Send + '_>>;
+}
+
+#[async_trait]
+/// Implements RootNodes for something deref'ing to a BTreeMap of Nodes, where
+/// the key is the node name.
+impl<T> RootNodes for T
+where
+    T: Deref<Target = BTreeMap<Bytes, Node>> + Send + Sync,
+{
+    async fn get_by_basename(&self, name: &[u8]) -> Result<Option<Node>, Error> {
+        Ok(self.get(name).cloned())
+    }
+
+    fn list(&self) -> Pin<Box<dyn Stream<Item = Result<Node, Error>> + Send + '_>> {
+        Box::pin(tokio_stream::iter(self.iter().map(|(_, v)| Ok(v.clone()))))
+    }
 }

tvix/store/Cargo.toml

@@ -47,9 +47,6 @@ test-case = "2.2.2"
 tempfile = "3.3.0"
 tokio-retry = "0.3.0"
 
-[dev-dependencies.libc]
-version = "0.2.144"
-
 [features]
 default = ["fuse", "tonic-reflection"]
 fuse = ["tvix-castore/fuse"]

tvix/store/src/pathinfoservice/fs/mod.rs

@@ -10,9 +10,6 @@ use tvix_castore::{blobservice::BlobService, directoryservice::DirectoryService}
 
 use super::PathInfoService;
 
-#[cfg(test)]
-mod tests;
-
 /// Helper to construct a [TvixStoreFs] from a [BlobService], [DirectoryService]
 /// and [PathInfoService].
 /// This avoids users to have to interact with the wrapper struct directly, as