Add test for phrase search with stop words

Originally written by ManyTheFish here:
https://gist.github.com/ManyTheFish/f840e37cb2d2e029ce05396b4d540762

Co-authored-by: ManyTheFish <many@meilisearch.com>

milli/tests/search/mod.rs

@@ -18,6 +18,7 @@ mod filters;
 mod query_criteria;
 mod sort;
 mod typo_tolerance;
+mod phrase_search;
 
 pub const TEST_QUERY: &'static str = "hello world america";
 

milli/tests/search/phrase_search.rs

@@ -0,0 +1,35 @@
+use milli::update::{IndexerConfig, Settings};
+use milli::{Index, Search, TermsMatchingStrategy};
+
+fn set_stop_words(index: &Index, stop_words: &[&str]) {
+    let mut wtxn = index.write_txn().unwrap();
+    let config = IndexerConfig::default();
+
+    let mut builder = Settings::new(&mut wtxn, &index, &config);
+    let stop_words = stop_words.into_iter().map(|s| s.to_string()).collect();
+    builder.set_stop_words(stop_words);
+    builder.execute(|_| ()).unwrap();
+    wtxn.commit().unwrap();
+}
+
+#[test]
+fn test_phrase_search_with_stop_words() {
+    let criteria = [];
+    let index = super::setup_search_index_with_criteria(&criteria);
+
+    // Add stop_words
+    set_stop_words(&index, &["a", "an", "the", "of"]);
+
+    // Phrase search containing stop words
+    let txn = index.read_txn().unwrap();
+
+    let mut search = Search::new(&txn, &index);
+    search.query("\"the use of force\"");
+    search.limit(10);
+    search.authorize_typos(false);
+    search.terms_matching_strategy(TermsMatchingStrategy::All);
+
+    let result = search.execute().unwrap();
+    // 1 document should match
+    assert_eq!(result.documents_ids.len(), 1);
+}