You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: pg_function_source_test.rs
    path of file: ./repos/martin/martin/tests
    
    the code of the file until where you have to start completion: #![cfg(feature = "postgres")]

use ctor::ctor;
use indoc::indoc;
use insta::assert_yaml_snapshot;
use martin::TileCoord;

pub mod utils;
pub use utils::*;

#[ctor]
fn init() {
    let _ = env_logger::builder().is_test(true).try_ini
    
async fn function_source_tilejson() {
    let mock = mock_sources(mock_pgcfg("connection_string: $DATABASE_URL")).await;
    let tj = source(&mock, "function_zxy_query").get_tilejson();
    assert_yaml_snapshot!(tj, @r###"
    ---
    tilejson: 3.0.0
    tiles: []
    name: function_zxy_query
    foo:
      bar: foo
    "###);
}