Simplify some unit tests

[loiclec]

Pull Request

What does this PR do?

Simplify the code that is used in unit tests to create and modify an index. Basically, the following code:

  let path = tempfile::tempdir().unwrap();
  let mut options = EnvOpenOptions::new();
  options.map_size(10 * 1024 * 1024); // 10 MB
  let index = Index::new(options, &path).unwrap();

  let mut wtxn = index.write_txn().unwrap();
  let content = documents!([
      { "id": 0, "name": "kevin" },
  ]);
  let config = IndexerConfig::default();
  let indexing_config = IndexDocumentsConfig::default();
  let builder =
      IndexDocuments::new(&mut wtxn, &index, &config, indexing_config, |_| ()).unwrap();
  let (builder, user_error) = builder.add_documents(content).unwrap();
  user_error.unwrap();
  builder.execute().unwrap();
  wtxn.commit.unwrap();

  let mut wtxn = index.write_txn().unwrap();
  let config = IndexerConfig::default();
  let mut builder = Settings::new(&mut wtxn, &index, &config);
  builder.set_primary_key(S("docid"));
  builder.set_filterable_fields(hashset! { S("label") });
  builder.execute(|_| ()).unwrap();
  wtxn.commit().unwrap();

becomes:

let index = TempIndex::new():
index.add_documents(documents!(
      { "id": 0, "name": "kevin" },
)).unwrap();
index.update_settings(|settings| {
    settings.set_primary_key(S("docid"));
    settings.set_filterable_fields(hashset! { S("label") });
}).unwrap();

Then there is a bunch of options to modify the indexing configs, the map size, to reuse a transaction, etc. For example:

let mut index = TempIndex::new_with_map_size(1000 * 4096 * 10);
index.index_documents_config.autogenerate_docids = true;
let mut wtxn = index.write_txn().unwrap();
index.update_settings_using_wtxn(&mut wtxn, |settings| {
    settings.set_primary_key(S("docids"));
}).unwrap();
wtxn.commit().unwrap();

[ManyTheFish]

Nice PR -619 lines!

I just requested some formatting changes.

Could you rebase your branch, please? Unfortunately, I added a new test recently that does not follow your new test structure 😬

[irevoire]

noice

[ManyTheFish]

Thank you @loiclec,

bors merge

[bors]

Build succeeded:

• Run Rustfmt
• Tests on macos-latest
• Tests on ubuntu-18.04
• Tests on windows-latest