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: test_api.rs
    path of file: ./repos/prisma-engines/schema-engine/sql-migration-tests/src
    
    the code of the file until where you have to start completion: pub use crate::assertions::{MigrationsAssertions, ResultSetExt, SchemaAssertion};
pub use expect_test::expect;
pub use schema_core::{
    json_rpc::types::{
        DbExecu
    
    pub fn generator_block(&self) -> String {
        let preview_feature_string = if self.root.preview_features().is_empty() {
            "".to_string()
        } else {
            let features = self
                .root
                .preview_features()
                .iter()
                .map(|f| format!(r#""{f}""#))
                .join(", ");

            format!("\npreviewFeatures = [{features}]")
        };

        let generator_block = format!(
            r#"generator client {{
                 provider = "prisma-client-js"{preview_feature_string}
               }}"#
        );
        generator_block
    }