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: tests.rs
    path of file: ./repos/fuel-core/crates/services/consensus_module/poa/src/verifier
    
    the code of the file until where you have to start completion: use super::*;
use crate::ports::MockDatabase;
use fuel_core_types::{
    blockchain::header::{
        ApplicationHeader,
        ConsensusHeader,
        GeneratedApplicationFields
    
fn test_verify_genesis_block_fields(input: Input) -> anyhow::Result<()> {
    let Input {
        block_header_merkle_root,
        prev_header_time,
        prev_header_da_height,
        ch,
        ah,
        txs,
    } = input;
    let mut d = MockDatabase::default();
    d.expect_block_header_merkle_root()
        .returning(move |_| Ok(block_header_merkle_root.into()));
    d.expect_block_header().returning(move |_| {
        let mut h = BlockHeader::default();
        h.set_time(prev_header_time);
        h.set_da_height(prev_header_da_height.into());
        Ok(h)
    });
    let mut b = Block::default();
    b.header_mut().set_consensus_header(ch);
    b.header_mut().set_application_header(ah);
    *b.transactions_mut() = txs;
    verify_block_fields(&d, &b)
}