Transaction queue tests update (#4734)

* shuffle tests

* update tests

* inc_nonce -> increment_nonce

substrate/client/transaction-pool/src/lib.rs

@@ -22,8 +22,6 @@
 mod api;
 pub mod error;
 
-#[cfg(test)]
-mod tests;
 #[cfg(any(feature = "test-helpers", test))]
 pub mod testing;
 
@@ -114,7 +112,8 @@ impl<PoolApi, Block> BasicPool<PoolApi, Block>
 		&self.pool
 	}
 
-	#[cfg(test)]
+	/// Get reference to the inner chain api, for tests only.
+	#[cfg(any(feature = "test-helpers", test))]
 	pub fn api(&self) -> &Arc<PoolApi> {
 		&self.api
 	}