Add support for disabling archive usage (#393)

That way fixture scripts can forcefully be executed which adds some
safety if the feature is actually used.

Author: Byron

DEVELOPMENT.md

@@ -168,6 +168,12 @@ by humans.
 Utilities to aid in keeping the project fresh and in sync can be found in the `Maintenance` section of the `makefile`. Run `make` to
 get an overview.
 
+## Reviewing PRs
+
+- be sure to clone locally and run tests with `GITOXIDE_TEST_IGNORE_ARCHIVES=1` to assure new fixture scripts (if there are any) are validated
+  on _MacOS_ and _Windows_. Note that linux doesn't need to be tested that way as CI on linux ignores them by merit of not checking them out
+  via `git-lfs`.
+
 ## Creating a release
 
 Run `make publish-all` to publish all crates in leaf-first order using `cargo release` based on the currently set version.

git-ref/tests/fixtures/generated-archives/make_repo_for_reflog.tar.xz

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:e7fe369e2c7a87e2688c6d0bf3bcdbe3e31754266f39f53a390f85551ba8258e
+oid sha256:75458d7d4cc29c1cab7a97e47578339dff84baf164fc3a9bcddc6f844482bab2
 size 10848

tests/tools/src/lib.rs

@@ -237,9 +237,22 @@ fn extract_archive(
     destination_dir: &Path,
     required_script_identity: u32,
 ) -> std::io::Result<(u32, Option<String>)> {
-    let mut archive_buf = Vec::<u8>::new();
-    let mut decoder = xz2::bufread::XzDecoder::new(std::io::BufReader::new(std::fs::File::open(archive)?));
-    std::io::copy(&mut decoder, &mut archive_buf)?;
+    let archive_buf: Vec<u8> = {
+        let mut buf = Vec::new();
+        let input_archive = std::fs::File::open(archive)?;
+        if std::env::var_os("GITOXIDE_TEST_IGNORE_ARCHIVES").is_some() {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::Other,
+                format!(
+                    "Ignoring archive at '{}' as GITOXIDE_TEST_IGNORE_ARCHIVES is set.",
+                    archive.display()
+                ),
+            ));
+        }
+        let mut decoder = xz2::bufread::XzDecoder::new(std::io::BufReader::new(input_archive));
+        std::io::copy(&mut decoder, &mut buf)?;
+        buf
+    };
 
     let mut entry_buf = Vec::<u8>::new();
     let (archive_identity, platform): (u32, _) = tar::Archive::new(std::io::Cursor::new(&mut &*archive_buf))