Add TxContext::get_last_created_object_id (#1371)

sui_programmability/framework/sources/TxContext.move

@@ -9,13 +9,19 @@ module Sui::TxContext {
     use Std::Errors;
     #[test_only]
     use Std::Vector;
+    #[test_only]
+    use Sui::ID::ID;
 
     /// Number of bytes in an tx hash (which will be the transaction digest)
     const TX_HASH_LENGTH: u64 = 32;
 
     /// Expected an tx hash of length 32, but found a different length
     const EBAD_TX_HASH_LENGTH: u64 = 0;
 
+    #[test_only]
+    /// Attempt to get the most recent created object ID when none has been created.
+    const ENO_IDS_CREATED: u64 = 1;
+
     /// Information about the transaction currently being executed.
     /// This cannot be constructed by a transaction--it is a privileged object created by
     /// the VM and passed in to the entrypoint of the transaction as `&mut TxContext`.
@@ -43,7 +49,7 @@ module Sui::TxContext {
     /// Generate a new, globally unique object ID with version 0
     public fun new_id(ctx: &mut TxContext): VersionedID {
         let ids_created = ctx.ids_created;
-        let id = ID::new_versioned_id(fresh_id(*&ctx.tx_hash, ids_created));
+        let id = ID::new_versioned_id(derive_id(*&ctx.tx_hash, ids_created));
         ctx.ids_created = ids_created + 1;
         id
     }
@@ -54,8 +60,8 @@ module Sui::TxContext {
         self.ids_created
     }
 
-    /// Native function for deriving an ID via hash(tx_hash || ids_created || domain_separator)
-    native fun fresh_id(tx_hash: vector<u8>, ids_created: u64): address;
+    /// Native function for deriving an ID via hash(tx_hash || ids_created)
+    native fun derive_id(tx_hash: vector<u8>, ids_created: u64): address;
 
     // ==== test-only functions ====
 
@@ -100,6 +106,14 @@ module Sui::TxContext {
         ids_created(self)
     }
 
+    #[test_only]
+    /// Return the most recent created object ID.
+    public fun get_last_created_object_id(self: &TxContext): ID {
+        let ids_created = self.ids_created;
+        assert!(ids_created > 0, ENO_IDS_CREATED);
+        ID::new(derive_id(*&self.tx_hash, ids_created - 1))
+    }
+
     #[test_only]
     /// Test-only function for creating a new signer from `signer_address`.
     native fun new_signer_from_address(signer_address: address): signer;

sui_programmability/framework/src/natives/mod.rs

@@ -59,7 +59,7 @@ pub fn all_natives(
         ("Transfer", "transfer_internal", transfer::transfer_internal),
         ("Transfer", "freeze_object", transfer::freeze_object),
         ("Transfer", "share_object", transfer::share_object),
-        ("TxContext", "fresh_id", tx_context::fresh_id),
+        ("TxContext", "derive_id", tx_context::derive_id),
         (
             "TxContext",
             "new_signer_from_address",

sui_programmability/framework/src/natives/tx_context.rs

@@ -15,7 +15,7 @@ use smallvec::smallvec;
 use std::{collections::VecDeque, convert::TryFrom};
 use sui_types::base_types::TransactionDigest;
 
-pub fn fresh_id(
+pub fn derive_id(
     context: &mut NativeContext,
     ty_args: Vec<Type>,
     mut args: VecDeque<Value>,

sui_programmability/framework/tests/TestScenarioTests.move

@@ -6,6 +6,7 @@ module Sui::TestScenarioTests {
     use Sui::ID;
     use Sui::TestScenario;
     use Sui::Transfer;
+    use Sui::TxContext;
 
     const ID_BYTES_MISMATCH: u64 = 0;
     const VALUE_MISMATCH: u64 = 1;
@@ -248,6 +249,20 @@ module Sui::TestScenarioTests {
         };
     }
 
+    #[test]
+    fun test_get_last_created_object_id() {
+        let sender = @0x0;
+        let scenario = TestScenario::begin(&sender);
+        {
+            let versioned_id = TestScenario::new_id(&mut scenario);
+            let id = *ID::inner(&versioned_id);
+            let obj = Object { id: versioned_id, value: 10 };
+            Transfer::transfer(obj, copy sender);
+            let ctx = TestScenario::ctx(&mut scenario);
+            assert!(id == TxContext::get_last_created_object_id(ctx), 0);
+        };
+    }
+
     #[test]
     #[expected_failure(abort_code = 100 /* ETRANSFER_SHARED_OBJECT */)]
     fun test_freeze_then_transfer() {