feat: checkout() now creates empty directories for submodules.

Author: Byron

gix-worktree-state/tests/fixtures/generated-archives/.gitignore

@@ -1,5 +1,6 @@
 make_ignore_and_attributes_setup.tar.xz
 make_mixed_without_submodules.tar.xz
+make_mixed.tar.xz
 make_mixed_without_submodules_and_symlinks.tar.xz
 make_attributes_baseline.tar.xz
 make_dangerous_symlink.tar.xz

gix-worktree-state/tests/fixtures/make_mixed.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+set -eu -o pipefail
+
+git init -q
+
+touch empty
+echo -n "content" > executable
+chmod +x executable
+
+mkdir dir
+echo "other content" > dir/content
+echo "* filter=arrow" > .gitattributes
+echo "executable -filter" >> .gitattributes
+echo ".gitattributes -filter" >> .gitattributes
+
+mkdir dir/sub-dir
+(cd dir/sub-dir && ln -sf ../content symlink)
+
+git add -A
+git commit -m "Commit"
+
+git init module1
+(cd module1
+  echo hello-from-submodule > f1
+  mkdir dir
+  : >dir/f2
+
+  git add . && git commit -m "init submodule"
+)
+
+git submodule add ./module1 m1
+git submodule add ./module1 modules/m1

gix-worktree-state/tests/state/checkout.rs

@@ -43,6 +43,26 @@ fn driver_exe() -> String {
     exe
 }
 
+#[test]
+fn submodules_are_instantiated_as_directories() -> crate::Result {
+    let mut opts = opts_from_probe();
+    opts.overwrite_existing = false;
+    let (_source_tree, destination, _index, _outcome) = checkout_index_in_tmp_dir(opts.clone(), "make_mixed")?;
+
+    for path in ["m1", "modules/m1"] {
+        let sm = destination.path().join(path);
+        assert!(sm.is_dir());
+        assure_is_empty(sm)?;
+    }
+
+    Ok(())
+}
+
+fn assure_is_empty(dir: impl AsRef<Path>) -> std::io::Result<()> {
+    assert_eq!(std::fs::read_dir(dir)?.count(), 0);
+    Ok(())
+}
+
 #[test]
 fn accidental_writes_through_symlinks_are_prevented_if_overwriting_is_forbidden() {
     let mut opts = opts_from_probe();
@@ -106,7 +126,7 @@ fn writes_through_symlinks_are_prevented_even_if_overwriting_is_allowed() {
                 if cfg!(windows) { "A-dir\\a" } else { "A-dir/a" },
                 "A-file",
                 "FAKE-DIR",
-                "FAKE-FILE"
+                if cfg!(windows) { "fake-file" } else { "FAKE-FILE" }
             ]),
         );
         assert!(outcome.collisions.is_empty());
@@ -165,7 +185,7 @@ fn overwriting_files_and_lone_directories_works() -> crate::Result {
         setup_filter_pipeline(opts.filters.options_mut());
         let (source, destination, _index, outcome) = checkout_index_in_tmp_dir_opts(
             opts.clone(),
-            "make_mixed_without_submodules",
+            "make_mixed",
             |_| true,
             |d| {
                 let empty = d.join("empty");