Add a fuzz test for index operations (clear, import, delete, settings)

It is very limited so far. It is meant to catch bugs with soft-deleted
document ids.

.gitignore

@@ -16,5 +16,5 @@ milli/target/
 ## ... unreviewed
 *.snap.new
 
-# Fuzzcheck data for the facet indexing fuzz test
-milli/fuzz/update::facet::incremental::fuzz::fuzz/
+# Fuzzcheck data
+milli/fuzz/*

filter-parser/src/lib.rs

@@ -38,6 +38,7 @@
 //! field = _geoRadius(12, 13, 14)
 //! ```
 //!
+#![feature(anonymous_lifetime_in_impl_trait)]
 
 mod condition;
 mod error;

milli/Cargo.toml

@@ -57,7 +57,7 @@ md5 = "0.7.0"
 rand = {version = "0.8.5", features = ["small_rng"] }
 
 [target.'cfg(fuzzing)'.dev-dependencies]
-fuzzcheck = "0.12.1"
+fuzzcheck = { path = "/Users/meilisearch/Documents/fuzzcheck-rs/fuzzcheck" }
 
 [features]
 default = [ "charabia/default" ]

milli/src/lib.rs

@@ -1,4 +1,4 @@
-#![cfg_attr(all(test, fuzzing), feature(no_coverage))]
+#![cfg_attr(all(test, fuzzing), feature(no_coverage, once_cell))]
 #[macro_use]
 pub mod documents;
 

milli/src/update/mod.rs

@@ -18,6 +18,8 @@ mod available_documents_ids;
 mod clear_documents;
 mod delete_documents;
 pub(crate) mod facet;
+#[cfg(all(fuzzing, test))]
+mod fuzz;
 mod index_documents;
 mod indexer_config;
 mod prefix_word_pairs;