How to add log to pallet's cargo.toml file to use log::info

Question

While doing the tutorial of "Build the Substrate Kitties Chain" there comes a section https://docs.substrate.io/tutorials/v3/kitties/pt1/#write-the-create_kitty-dispatchable

In this there it says 'In order to use log::info, add this to your pallet's Cargo.toml file, using the matching version as Substrate upstream.'

So How to add log in cargo.toml?

Answer 1

To add log in pallets\kitties\src\cargo.toml first go into cargo.toml file and in the [dependencies] section add: log = {version = "0.4.14", feature = ["derive"]}

Just keep in mind version may change depending upon the updates. So change it accordingly. Currently on the date of writing this answer version is 0.4.14

Answer 2

Use Substrate's built-in sp-tracing! https://www.youtube.com/watch?v=ZSipV1LLUzM

add sp-tracing in the pallet cargo file under dev dependencies:

sp-tracing = { version = "6.0.0", default-features = false, git = "https://github.com/paritytech/substrate.git", branch = "polkadot-v0.9.37" }

use it in your code

use frame_support::{log::{info, warn}, .. };
  info!("info num: {:?}", num);
  warn!("warn num: {:?}", num);

in your pallet/mock:

pub fn new_test_ext() -> sp_io::TestExternalities {
    sp_tracing::try_init_simple();// Add this line
    system::GenesisConfig::default().build_storage::<Test>().unwrap().into()
}

Run tests with "RUST_LOG=info "

$ RUST_LOG=info cargo test -p pallet-template it_

will run tests that starts with "it_"