Rename test group overlay-local-store -> local-overlay-store

Makes it match the store name (`local-overlay`) and experimental feature
name (`local-overlay-store`)._

tests/local-overlay-store/common.sh

@@ -0,0 +1,83 @@
+source ../common.sh
+
+requireEnvironment () {
+  requireSandboxSupport
+  [[ $busybox =~ busybox ]] || skipTest "no busybox"
+  if [[ $(uname) != Linux ]]; then skipTest "Need Linux for overlayfs"; fi
+  needLocalStore "The test uses --store always so we would just be bypassing the daemon"
+}
+
+addConfig () {
+    echo "$1" >> "$NIX_CONF_DIR/nix.conf"
+}
+
+setupConfig () {
+  addConfig "require-drop-supplementary-groups = false"
+  addConfig "build-users-group = "
+}
+
+enableFeatures "local-overlay-store"
+
+storeDirs () {
+  # Attempt to create store dirs on tmpfs volume.
+  # This ensures lowerdir, upperdir and workdir will be on
+  # a consistent filesystem that fully supports OverlayFS.
+  storeVolume="$TEST_ROOT/stores"
+  mkdir -p "$storeVolume"
+  mount -t tmpfs tmpfs "$storeVolume" || true  # But continue anyway if that fails.
+
+  storeA="$storeVolume/store-a"
+  storeBTop="$storeVolume/store-b"
+  storeBRoot="$storeVolume/merged-store"
+  storeB="local-overlay?root=$storeBRoot&lower-store=$storeA&upper-layer=$storeBTop"
+  # Creating testing directories
+  mkdir -p "$storeVolume"/{store-a/nix/store,store-b,merged-store/nix/store,workdir}
+}
+
+# Mounting Overlay Store
+mountOverlayfs () {
+  mount -t overlay overlay \
+    -o lowerdir="$storeA/nix/store" \
+    -o upperdir="$storeBTop" \
+    -o workdir="$storeVolume/workdir" \
+    "$storeBRoot/nix/store" \
+    || skipTest "overlayfs is not supported"
+
+  cleanupOverlay () {
+    umount "$storeBRoot/nix/store"
+    rm -r $storeVolume/workdir
+  }
+  trap cleanupOverlay EXIT
+}
+
+remountOverlayfs () {
+  mount -o remount "$storeBRoot/nix/store"
+}
+
+toRealPath () {
+  storeDir=$1; shift
+  storePath=$1; shift
+  echo $storeDir$(echo $storePath | sed "s^${NIX_STORE_DIR:-/nix/store}^^")
+}
+
+initLowerStore () {
+  # Init lower store with some stuff
+  nix-store --store "$storeA" --add ../dummy
+
+  # Build something in lower store
+  drvPath=$(nix-instantiate --store $storeA ../hermetic.nix --arg busybox "$busybox" --arg seed 1)
+  path=$(nix-store --store "$storeA" --realise $drvPath)
+}
+
+execUnshare () {
+  exec unshare --mount --map-root-user "$SHELL" "$@"
+}
+
+addTextToStore() {
+  storeDir=$1; shift
+  filename=$1; shift
+  content=$1; shift
+  filePath="$TEST_HOME/$filename"
+  echo "$content" > "$filePath"
+  nix-store --store "$storeDir" --add "$filePath"
+}