lib.rs

	/// #    #[derive_impl(frame_system::config_preludes::TestDefaultConfig)]
	/// #    impl frame_system::Config for Runtime {
	/// #        type Block = frame_system::mocking::MockBlock<Self>;
	/// #    }
	///     construct_runtime! {
	///         pub enum Runtime {
	///             System: frame_system,
	///             Custom: custom_pallet
	///         }
	///     }
	///
	/// #    TestExternalities::new_empty().execute_with(|| {
	///     let origin: RuntimeOrigin = frame_system::RawOrigin::Signed(10).into();
	///     // calling into a dispatchable from within the runtime is simply a function call.
	///         let _ = custom_pallet::Pallet::<Runtime>::some_dispatchable(origin.clone(), 10);
	///
	///     // calling into a dispatchable from the outer world involves constructing the bytes of
	///     let call = custom_pallet::Call::<Runtime>::some_dispatchable { input: 10 };
	///     let _ = call.clone().dispatch_bypass_filter(origin);
	///
	///     // the routing of a dispatchable is simply done through encoding of the `Call` enum,
	///     // which is the index of the variant, followed by the arguments.
	///     assert_eq!(call.encode(), vec![0u8, 10, 0, 0, 0]);
	///
	///     // notice how in the encoding of the second function, the first byte is different and
	///     // referring to the second variant of `enum Call`.
	///     let call = custom_pallet::Call::<Runtime>::other { input: 10 };
	///     assert_eq!(call.encode(), vec![1u8, 10, 0, 0, 0, 0, 0, 0, 0]);
	///     #    });
	/// }
	/// ```
	///
	/// Further properties of dispatchable functions are as follows:
	///
	/// - Unless if annotated by `dev_mode`, it must contain [`weight`] to denote the
	///   pre-dispatch weight consumed.
	/// - The dispatchable must declare its index via [`call_index`], which can override the
	///   position of a function in `enum Call`.
	/// - The first argument is always an `OriginFor` (or `T::RuntimeOrigin`).
	/// - The return type is always [`crate::dispatch::DispatchResult`] (or
	///   [`crate::dispatch::DispatchResultWithPostInfo`]).
	///
	/// **WARNING**: modifying dispatchables, changing their order (i.e. using [`call_index`]),
	/// removing some, etc., must be done with care. This will change the encoding of the , and
	/// the call can be stored on-chain (e.g. in `pallet-scheduler`). Thus, migration might be
	/// needed. This is why the use of `call_index` is mandatory by default in FRAME.
	///
	/// ## Default Behavior
	///
	/// If no `#[pallet::call]` exists, then a default implementation corresponding to the
	/// following code is automatically generated:
	///
	/// ```
	/// #[frame_support::pallet(dev_mode)]
	/// mod pallet {
	/// 	#[pallet::pallet]
	/// 	pub struct Pallet<T>(_);
	///
	/// 	#[pallet::call] // <- automatically generated
	/// 	impl<T: Config> Pallet<T> {} // <- automatically generated
	///
	/// 	#[pallet::config]
	/// 	pub trait Config: frame_system::Config {}
	/// }
	/// ```
	pub use frame_support_procedural::call;

	/// Enforce the index of a variant in the generated `enum Call`.
	///
	/// See [`call`] for more information.
	///
	/// All call indexes start from 0, until it encounters a dispatchable function with a
	/// defined call index. The dispatchable function that lexically follows the function with
	/// a defined call index will have that call index, but incremented by 1, e.g. if there are
	/// 3 dispatchable functions `fn foo`, `fn bar` and `fn qux` in that order, and only `fn
	/// bar` has a call index of 10, then `fn qux` will have an index of 11, instead of 1.
	pub use frame_support_procedural::call_index;

	/// Declares the arguments of a [`call`] function to be encoded using
	/// [`codec::Compact`].
	///
	/// This will results in smaller extrinsic encoding.
	///
	/// A common example of `compact` is for numeric values that are often times far far away
	/// from their theoretical maximum. For example, in the context of a crypto-currency, the
	/// balance of an individual account is oftentimes way less than what the numeric type
	/// allows. In all such cases, using `compact` is sensible.
	///
	/// ```
	/// #[frame_support::pallet(dev_mode)]
	/// pub mod custom_pallet {
	/// #   use frame_support::pallet_prelude::*;
	/// #   use frame_system::pallet_prelude::*;
	/// #   #[pallet::config]
	/// #   pub trait Config: frame_system::Config {}
	/// #   #[pallet::pallet]
	/// #   pub struct Pallet<T>(_);
	/// #   use frame_support::traits::BuildGenesisConfig;
	///     #[pallet::call]
	///     impl<T: Config> Pallet<T> {
	///         pub fn some_dispatchable(_origin: OriginFor<T>, #[pallet::compact] _input: u32) -> DispatchResult {
	///             Ok(())
	///         }
	///     }
	/// }
	pub use frame_support_procedural::compact;

	/// Allows you to define the genesis configuration for the pallet.
	///
	/// Item is defined as either an enum or a struct. It needs to be public and implement the
	/// trait [`frame_support::traits::BuildGenesisConfig`].
	///
	/// See [`genesis_build`] for an example.
	pub use frame_support_procedural::genesis_config;

	/// Allows you to define how the state of your pallet at genesis is built. This
	/// takes as input the `GenesisConfig` type (as `self`) and constructs the pallet's initial
	/// state.
	///
	/// The fields of the `GenesisConfig` can in turn be populated by the chain-spec.
	///
	/// ## Example
	///
	/// ```
	/// #[frame_support::pallet]
	/// pub mod pallet {
	/// # 	#[pallet::config]
	/// # 	pub trait Config: frame_system::Config {}
	/// # 	#[pallet::pallet]
	/// # 	pub struct Pallet<T>(_);
	/// # 	use frame_support::traits::BuildGenesisConfig;
	///     #[pallet::genesis_config]
	///     #[derive(frame_support::DefaultNoBound)]
	///     pub struct GenesisConfig<T: Config> {
	///         foo: Vec<T::AccountId>
	///     }
	///
	///     #[pallet::genesis_build]
	///     impl<T: Config> BuildGenesisConfig for GenesisConfig<T> {
	///         fn build(&self) {
	///             // use &self to access fields.
	///             let foo = &self.foo;
	///             todo!()
	///         }
	///     }
	/// }
	/// ```
	///
	/// ## Former Usage
	///
	/// Prior to <https://github.com/paritytech/substrate/pull/14306>, the following syntax was used.
	/// This is deprecated and will soon be removed.
	///
	/// ```
	/// #[frame_support::pallet]
	/// pub mod pallet {
	/// #     #[pallet::config]
	/// #     pub trait Config: frame_system::Config {}
	/// #     #[pallet::pallet]
	/// #     pub struct Pallet<T>(_);
	/// #     use frame_support::traits::GenesisBuild;
	///     #[pallet::genesis_config]
	///     #[derive(frame_support::DefaultNoBound)]
	///     pub struct GenesisConfig<T: Config> {
	/// 		foo: Vec<T::AccountId>
	/// 	}
	///
	///     #[pallet::genesis_build]
	///     impl<T: Config> GenesisBuild<T> for GenesisConfig<T> {
	///         fn build(&self) {
	///             todo!()
	///         }
	///     }
	/// }
	/// ```
	pub use frame_support_procedural::genesis_build;

	/// Allows adding an associated type trait bounded by
	/// [`Get`](frame_support::pallet_prelude::Get) from [`pallet::config`](`macro@config`)
	/// into metadata.
	///
	/// ## Example
	///
	/// ```
	/// #[frame_support::pallet]
	/// mod pallet {
	///     use frame_support::pallet_prelude::*;
	///     # #[pallet::pallet]
	///     # pub struct Pallet<T>(_);
	///     #[pallet::config]
	///     pub trait Config: frame_system::Config {
	/// 		/// This is like a normal `Get` trait, but it will be added into metadata.
	/// 		#[pallet::constant]
	/// 		type Foo: Get<u32>;
	/// 	}
	/// }
	/// ```
	pub use frame_support_procedural::constant;

	/// Declares a type alias as a storage item.
	///
	/// Storage items are pointers to data stored on-chain (the *blockchain state*), under a
	/// specific key. The exact key is dependent on the type of the storage.
	///
	/// > From the perspective of this pallet, the entire blockchain state is abstracted behind
	/// > a key-value api, namely [`sp_io::storage`].
	///
	/// ## Storage Types
	///
	/// The following storage types are supported by the `#[storage]` macro. For specific
	/// information about each storage type, refer to the documentation of the respective type.
	///
	/// * [`StorageValue`](crate::storage::types::StorageValue)
	/// * [`StorageMap`](crate::storage::types::StorageMap)
	/// * [`CountedStorageMap`](crate::storage::types::CountedStorageMap)
	/// * [`StorageDoubleMap`](crate::storage::types::StorageDoubleMap)
	/// * [`StorageNMap`](crate::storage::types::StorageNMap)
	/// * [`CountedStorageNMap`](crate::storage::types::CountedStorageNMap)
	///
	/// ## Storage Type Usage
	///
	/// The following details are relevant to all of the aforementioned storage types.
	/// Depending on the exact storage type, it may require the following generic parameters:
	///
	/// * [`Prefix`](#prefixes) - Used to give the storage item a unique key in the underlying
	///   storage.
	/// * `Key` - Type of the keys used to store the values,
	/// * `Value` - Type of the value being stored,
	/// * [`Hasher`](#hashers) - Used to ensure the keys of a map are uniformly distributed,
	/// * [`QueryKind`](#querykind) - Used to configure how to handle queries to the underlying
	///   storage,
	/// * `OnEmpty` - Used to handle missing values when querying the underlying storage,
	/// * `MaxValues` - _not currently used_.
	///
	/// Each `Key` type requires its own designated `Hasher` declaration, so that
	/// [`StorageDoubleMap`](frame_support::storage::types::StorageDoubleMap) needs two of
	/// each, and [`StorageNMap`](frame_support::storage::types::StorageNMap) needs `N` such
	/// pairs. Since [`StorageValue`](frame_support::storage::types::StorageValue) only stores
	/// a single element, no configuration of hashers is needed.
	///
	/// ### Syntax
	///
	/// Two general syntaxes are supported, as demonstrated below:
	///
	/// 1. Named type parameters, e.g., `type Foo<T> = StorageValue<Value = u32>`.
	/// 2. Positional type parameters, e.g., `type Foo<T> = StorageValue<_, u32>`.
	///
	/// In both instances, declaring the generic parameter `<T>` is mandatory. Optionally, it
	/// can also be explicitly declared as `<T: Config>`. In the compiled code, `T` will
	/// automatically include the trait bound `Config`.
	///
	/// Note that in positional syntax, the first generic type parameter must be `_`.
	///
	/// #### Example
	///
	/// ```
	/// #[frame_support::pallet]
	/// mod pallet {
	///     # use frame_support::pallet_prelude::*;
	///     # #[pallet::config]
	///     # pub trait Config: frame_system::Config {}
	///     # #[pallet::pallet]
	///     # pub struct Pallet<T>(_);
	///     /// Positional syntax, without bounding `T`.
	///     #[pallet::storage]
	///     pub type Foo<T> = StorageValue<_, u32>;
	///
	///     /// Positional syntax, with bounding `T`.
	///     #[pallet::storage]
	///     pub type Bar<T: Config> = StorageValue<_, u32>;
	///
	///     /// Named syntax.
	///     #[pallet::storage]
	///     pub type Baz<T> = StorageMap<Hasher = Blake2_128Concat, Key = u32, Value = u32>;
	/// }
	/// ```
	///
	/// ### QueryKind
	///
	/// Every storage type mentioned above has a generic type called
	/// [`QueryKind`](frame_support::storage::types::QueryKindTrait) that determines its
	/// "query" type. This refers to the kind of value returned when querying the storage, for
	/// instance, through a `::get()` method.
	///
	/// There are three types of queries:
	///
	/// 1. [`OptionQuery`](frame_support::storage::types::OptionQuery): The default query type.
	///    It returns `Some(V)` if the value is present, or `None` if it isn't, where `V` is
	///    the value type.
	/// 2. [`ValueQuery`](frame_support::storage::types::ValueQuery): Returns the value itself
	///    if present; otherwise, it returns `Default::default()`. This behavior can be
	///    adjusted with the `OnEmpty` generic parameter, which defaults to `OnEmpty =
	///    GetDefault`.
	/// 3. [`ResultQuery`](frame_support::storage::types::ResultQuery): Returns `Result<V, E>`,
	///    where `V` is the value type.
	///
	/// See [`QueryKind`](frame_support::storage::types::QueryKindTrait) for further examples.
	///
	/// ### Optimized Appending
	///
	/// All storage items — such as
	/// [`StorageValue`](frame_support::storage::types::StorageValue),
	/// [`StorageMap`](frame_support::storage::types::StorageMap), and their variants—offer an
	/// `::append()` method optimized for collections. Using this method avoids the
	/// inefficiency of decoding and re-encoding entire collections when adding items. For
	/// instance, consider the storage declaration `type MyVal<T> = StorageValue<_, Vec<u8>,
	/// ValueQuery>`. With `MyVal` storing a large list of bytes, `::append()` lets you
	/// directly add bytes to the end in storage without processing the full list. Depending on
	/// the storage type, additional key specifications may be needed.
	///
	/// #### Example
	#[doc = docify::embed!("src/lib.rs", example_storage_value_append)]
	/// Similarly, there also exists a `::try_append()` method, which can be used when handling
	/// types where an append operation might fail, such as a
	/// [`BoundedVec`](frame_support::BoundedVec).
	///
	/// #### Example
	#[doc = docify::embed!("src/lib.rs", example_storage_value_try_append)]
	/// ### Optimized Length Decoding
	///
	/// All storage items — such as
	/// [`StorageValue`](frame_support::storage::types::StorageValue),
	/// [`StorageMap`](frame_support::storage::types::StorageMap), and their counterparts —
	/// incorporate the `::decode_len()` method. This method allows for efficient retrieval of
	/// a collection's length without the necessity of decoding the entire dataset.
	/// #### Example
	#[doc = docify::embed!("src/lib.rs", example_storage_value_decode_len)]
	/// ### Hashers
	///
	/// For all storage types, except
	/// [`StorageValue`](frame_support::storage::types::StorageValue), a set of hashers needs
	/// to be specified. The choice of hashers is crucial, especially in production chains. The
	/// purpose of storage hashers in maps is to ensure the keys of a map are
	/// uniformly distributed. An unbalanced map/trie can lead to inefficient performance.
	///
	/// In general, hashers are categorized as either cryptographically secure or not. The
	/// former is slower than the latter. `Blake2` and `Twox` serve as examples of each,
	/// respectively.
	///
	/// As a rule of thumb:
	///
	/// 1. If the map keys are not controlled by end users, or are cryptographically secure by
	/// definition (e.g., `AccountId`), then the use of cryptographically secure hashers is NOT
	/// required.
	/// 2. If the map keys are controllable by the end users, cryptographically secure hashers
	/// should be used.
	///
	/// For more information, look at the types that implement
	/// [`frame_support::StorageHasher`](frame_support::StorageHasher).
	///
	/// Lastly, it's recommended for hashers with "concat" to have reversible hashes. Refer to
	/// the implementors section of
	/// [`hash::ReversibleStorageHasher`](frame_support::hash::ReversibleStorageHasher).
	///
	/// ### Prefixes
	///
	/// Internally, every storage type generates a "prefix". This prefix serves as the initial
	/// segment of the key utilized to store values in the on-chain state (i.e., the final key
	/// used in [`sp_io::storage`](sp_io::storage)). For all storage types, the following rule
	/// applies:
	///
	/// > The storage prefix begins with `twox128(pallet_prefix) ++ twox128(STORAGE_PREFIX)`,
	/// > where
	/// > `pallet_prefix` is the name assigned to the pallet instance in
	/// > [`frame_support::construct_runtime`](frame_support::construct_runtime), and
	/// > `STORAGE_PREFIX` is the name of the `type` aliased to a particular storage type, such
	/// > as
	/// > `Foo` in `type Foo<T> = StorageValue<..>`.
	///
	/// For [`StorageValue`](frame_support::storage::types::StorageValue), no additional key is
	/// required. For map types, the prefix is extended with one or more keys defined by the
	/// map.
	///
	/// #### Example
	#[doc = docify::embed!("src/lib.rs", example_storage_value_map_prefixes)]
	/// ## Related Macros
	///
	/// The following attribute macros can be used in conjunction with the `#[storage]` macro:
	///
	/// * [`macro@getter`]: Creates a custom getter function.
	/// * [`macro@storage_prefix`]: Overrides the default prefix of the storage item.
	/// * [`macro@unbounded`]: Declares the storage item as unbounded.
	/// * [`macro@disable_try_decode_storage`]: Declares that try-runtime checks should not
	///   attempt to decode the storage item.
	///
	/// #### Example
	/// ```
	/// #[frame_support::pallet]
	/// mod pallet {
	///     # use frame_support::pallet_prelude::*;
	///     # #[pallet::config]
	///     # pub trait Config: frame_system::Config {}
	///     # #[pallet::pallet]
	///     # pub struct Pallet<T>(_);
	/// 	/// A kitchen-sink StorageValue, with all possible additional attributes.
	///     #[pallet::storage]
	/// 	#[pallet::getter(fn foo)]
	/// 	#[pallet::storage_prefix = "OtherFoo"]
	/// 	#[pallet::unbounded]
	/// 	#[pallet::disable_try_decode_storage]
	///     pub type Foo<T> = StorageValue<_, u32, ValueQuery>;
	/// }
	/// ```
	pub use frame_support_procedural::storage;

	/// Allows defining conditions for a task to run.
	///
	/// This attribute is attached to a function inside an `impl` block annotated with
	/// [`pallet::tasks_experimental`](`tasks_experimental`) to define the conditions for a
	/// given work item to be valid.
	///
	/// It takes a closure as input, which is then used to define the condition. The closure
	/// should have the same signature as the function it is attached to, except that it should
	/// return a `bool` instead.
	pub use frame_support_procedural::task_condition;

	/// Allows defining an index for a task.
	///
	/// This attribute is attached to a function inside an `impl` block annotated with
	/// [`pallet::tasks_experimental`](`tasks_experimental`) to define the index of a given
	/// work item.
	///
	/// It takes an integer literal as input, which is then used to define the index. This
	/// index should be unique for each function in the `impl` block.
	pub use frame_support_procedural::task_index;

	/// Allows defining an iterator over available work items for a task.
	///
	/// This attribute is attached to a function inside an `impl` block annotated with
	/// [`pallet::tasks_experimental`](`tasks_experimental`).
	///
	/// It takes an iterator as input that yields a tuple with same types as the function
	/// arguments.
	pub use frame_support_procedural::task_list;

	/// Allows defining the weight of a task.
	///
	/// This attribute is attached to a function inside an `impl` block annotated with
	/// [`pallet::tasks_experimental`](`tasks_experimental`) define the weight of a given work
	/// item.
	///
	/// It takes a closure as input, which should return a `Weight` value.
	pub use frame_support_procedural::task_weight;

	/// Allows you to define some service work that can be recognized by a script or an
	/// off-chain worker.
	///
	/// Such a script can then create and submit all such work items at any given time.
	///
	/// These work items are defined as instances of the [`Task`](frame_support::traits::Task)
	/// trait. [`pallet:tasks_experimental`](`tasks_experimental`) when attached to an `impl`
	/// block inside a pallet, will generate an enum `Task<T>` whose variants are mapped to
	/// functions inside this `impl` block.
	///
	/// Each such function must have the following set of attributes:
	///
	/// * [`pallet::task_list`](`task_list`)
	/// * [`pallet::task_condition`](`task_condition`)
	/// * [`pallet::task_weight`](`task_weight`)
	/// * [`pallet::task_index`](`task_index`)
	///
	/// All of such Tasks are then aggregated into a `RuntimeTask` by
	/// [`construct_runtime`](frame_support::construct_runtime).
	///
	/// Finally, the `RuntimeTask` can then used by a script or off-chain worker to create and
	/// submit such tasks via an extrinsic defined in `frame_system` called `do_task`.
	///
	/// When submitted as unsigned transactions (for example via an off-chain workder), note
	/// that the tasks will be executed in a random order.
	///
	/// ## Example
	#[doc = docify::embed!("src/tests/tasks.rs", tasks_example)]
	/// Now, this can be executed as follows:
	#[doc = docify::embed!("src/tests/tasks.rs", tasks_work)]
	pub use frame_support_procedural::tasks_experimental;

	/// Allows a pallet to declare a type as an origin.
	///
	/// If defined as such, this type will be amalgamated at the runtime level into
	/// `RuntimeOrigin`, very similar to [`call`], [`error`] and [`event`]. See
	/// [`composite_enum`] for similar cases.
	///
	/// Origin is a complex FRAME topics and is further explained in `polkadot_sdk_docs`.
	///
	/// ## Syntax Variants
	///
	/// ```
	/// #[frame_support::pallet]
	/// mod pallet {
	///     # use frame_support::pallet_prelude::*;
	///     # #[pallet::config]
	///     # pub trait Config: frame_system::Config {}
	///     # #[pallet::pallet]
	///     # pub struct Pallet<T>(_);
	/// 	/// On the spot declaration.
	///     #[pallet::origin]
	/// 	#[derive(PartialEq, Eq, Clone, RuntimeDebug, Encode, Decode, TypeInfo, MaxEncodedLen)]
	/// 	pub enum Origin {
	/// 		Foo,
	/// 		Bar,
	/// 	}
	/// }
	/// ```
	///
	/// Or, more commonly used:
	///
	/// ```
	/// #[frame_support::pallet]
	/// mod pallet {
	///     # use frame_support::pallet_prelude::*;
	///     # #[pallet::config]
	///     # pub trait Config: frame_system::Config {}
	///     # #[pallet::pallet]
	///     # pub struct Pallet<T>(_);
	/// 	#[derive(PartialEq, Eq, Clone, RuntimeDebug, Encode, Decode, TypeInfo, MaxEncodedLen)]
	/// 	pub enum RawOrigin {
	/// 		Foo,
	/// 		Bar,
	/// 	}
	///
	/// 	#[pallet::origin]
	/// 	pub type Origin = RawOrigin;
	/// }
	/// ```
	///
	/// ## Warning
	///
	/// Modifying any pallet's origin type will cause the runtime level origin type to also
	/// change in encoding. If stored anywhere on-chain, this will require a data migration.
	///
	/// Read more about origins at the [Origin Reference
	/// Docs](../../polkadot_sdk_docs/reference_docs/frame_origin/index.html).
	pub use frame_support_procedural::origin;
}

#[deprecated(note = "Will be removed after July 2023; Use `sp_runtime::traits` directly instead.")]
pub mod error {
	#[doc(hidden)]
	pub use sp_runtime::traits::{BadOrigin, LookupError};
}

#[doc(inline)]
pub use frame_support_procedural::register_default_impl;

// Generate a macro that will enable/disable code based on `std` feature being active.
sp_core::generate_feature_enabled_macro!(std_enabled, feature = "std", $);

// Helper for implementing GenesisBuilder runtime API
pub mod genesis_builder_helper;

#[cfg(test)]
mod test {
	// use super::*;
	use crate::{
		hash::*,
		storage::types::{StorageMap, StorageValue, ValueQuery},
		traits::{ConstU32, StorageInstance},
		BoundedVec,
	};
	use sp_io::{hashing::twox_128, TestExternalities};

	struct Prefix;
	impl StorageInstance for Prefix {
		fn pallet_prefix() -> &'static str {
			"test"
		}
		const STORAGE_PREFIX: &'static str = "foo";
	}

	struct Prefix1;
	impl StorageInstance for Prefix1 {
		fn pallet_prefix() -> &'static str {
			"test"
		}
		const STORAGE_PREFIX: &'static str = "MyVal";
	}
	struct Prefix2;
	impl StorageInstance for Prefix2 {
		fn pallet_prefix() -> &'static str {
			"test"
		}
		const STORAGE_PREFIX: &'static str = "MyMap";
	}

	#[docify::export]
	#[test]
	pub fn example_storage_value_try_append() {
		type MyVal = StorageValue<Prefix, BoundedVec<u8, ConstU32<10>>, ValueQuery>;

		TestExternalities::default().execute_with(|| {
			MyVal::set(BoundedVec::try_from(vec![42, 43]).unwrap());
			assert_eq!(MyVal::get(), vec![42, 43]);
			// Try to append a single u32 to BoundedVec stored in `MyVal`
			assert_ok!(MyVal::try_append(40));
			assert_eq!(MyVal::get(), vec![42, 43, 40]);
		});
	}

	#[docify::export]
	#[test]
	pub fn example_storage_value_append() {
		type MyVal = StorageValue<Prefix, Vec<u8>, ValueQuery>;

		TestExternalities::default().execute_with(|| {
			MyVal::set(vec![42, 43]);
			assert_eq!(MyVal::get(), vec![42, 43]);
			// Append a single u32 to Vec stored in `MyVal`
			MyVal::append(40);
			assert_eq!(MyVal::get(), vec![42, 43, 40]);
		});
	}

	#[docify::export]
	#[test]
	pub fn example_storage_value_decode_len() {
		type MyVal = StorageValue<Prefix, BoundedVec<u8, ConstU32<10>>, ValueQuery>;

		TestExternalities::default().execute_with(|| {
			MyVal::set(BoundedVec::try_from(vec![42, 43]).unwrap());
			assert_eq!(MyVal::decode_len().unwrap(), 2);
		});
	}

	#[docify::export]
	#[test]
	pub fn example_storage_value_map_prefixes() {
		type MyVal = StorageValue<Prefix1, u32, ValueQuery>;
		type MyMap = StorageMap<Prefix2, Blake2_128Concat, u16, u32, ValueQuery>;
		TestExternalities::default().execute_with(|| {
			// This example assumes `pallet_prefix` to be "test"
			// Get storage key for `MyVal` StorageValue
			assert_eq!(
				MyVal::hashed_key().to_vec(),
				[twox_128(b"test"), twox_128(b"MyVal")].concat()
			);
			// Get storage key for `MyMap` StorageMap and `key` = 1
			let mut k: Vec<u8> = vec![];
			k.extend(&twox_128(b"test"));
			k.extend(&twox_128(b"MyMap"));
			k.extend(&1u16.blake2_128_concat());
			assert_eq!(MyMap::hashed_key_for(1).to_vec(), k);
		});
	}
}