Contracts Bump ApiVersion and add test (#3619)

ApiVersion should have been bumped with
https://github.com/paritytech/polkadot-sdk/pull/3606
this does that and add a test so we don't forget to do that everytime

substrate/frame/contracts/proc-macro/src/lib.rs

@@ -497,9 +497,14 @@ fn expand_docs(def: &EnvDef) -> TokenStream2 {
 fn expand_env(def: &EnvDef, docs: bool) -> TokenStream2 {
 	let impls = expand_impls(def);
 	let docs = docs.then_some(expand_docs(def)).unwrap_or(TokenStream2::new());
+	let stable_api_count = def.host_funcs.iter().filter(|f| f.is_stable).count();
 
 	quote! {
 		pub struct Env;
+
+		#[cfg(test)]
+		pub const STABLE_API_COUNT: usize = #stable_api_count;
+
 		#impls
 		/// Documentation of the API (host functions) available to contracts.
 		///

substrate/frame/contracts/src/lib.rs

@@ -222,10 +222,19 @@ pub struct Environment<T: Config> {
 pub struct ApiVersion(u16);
 impl Default for ApiVersion {
 	fn default() -> Self {
-		Self(1)
+		Self(2)
 	}
 }
 
+#[test]
+fn api_version_is_up_to_date() {
+	assert_eq!(
+		109,
+		crate::wasm::STABLE_API_COUNT,
+		"Stable API count has changed. Bump the returned value of ApiVersion::default() and update the test."
+	);
+}
+
 #[frame_support::pallet]
 pub mod pallet {
 	use super::*;

substrate/frame/contracts/src/wasm/mod.rs

@@ -21,6 +21,9 @@
 mod prepare;
 mod runtime;
 
+#[cfg(test)]
+pub use runtime::STABLE_API_COUNT;
+
 #[cfg(doc)]
 pub use crate::wasm::runtime::api_doc;
 

substrate/frame/contracts/src/wasm/runtime.rs

@@ -987,7 +987,6 @@ impl<'a, E: Ext + 'a> Runtime<'a, E> {
 // for every function.
 #[define_env(doc)]
 pub mod env {
-
 	/// Set the value at the given key in the contract storage.
 	/// See [`pallet_contracts_uapi::HostFn::set_storage`]
 	#[prefixed_alias]