feat(rpc-server): Custom method to emulate transaction (#408)

* feat(rpc-server): Custom method to emulate transaction

* fmt

* function call Code storage update for transaction emulation

* collect cross call results

* make clippy happy

* tx emulator improvement

* add docstring

* add docs for new custom method

* improvement

Author: kobayurii

Cargo.lock

@@ -57,6 +57,7 @@ near-chain-configs = { git = "https://github.com/kobayurii/nearcore", branch = "
 near-crypto = { git = "https://github.com/kobayurii/nearcore", branch = "fork/2.6.5" }
 near-jsonrpc = { git = "https://github.com/kobayurii/nearcore", branch = "fork/2.6.5" }
 near-parameters = { git = "https://github.com/kobayurii/nearcore", branch = "fork/2.6.5" }
+node-runtime =  { git = "https://github.com/kobayurii/nearcore", branch = "fork/2.6.5" }
 near-vm-runner = { git = "https://github.com/kobayurii/nearcore", branch = "fork/2.6.5" , features = [
     "wasmer0_vm",
     "wasmer2_vm",

Cargo.toml

@@ -116,3 +116,51 @@ Response:
   }
 }
 ```
+
+# emulate_tx
+
+The `emulate_tx` method is a custom method that allows you to estimate transaction costs and simulate its execution without actually sending it to the network. For now simulation supports only `FunctionCall` action, for other actions it will return only estimate fee.
+
+## How to use it
+### Example
+
+Request:
+```json
+{
+  "jsonrpc": "2.0",
+  "id": "dontcare",
+  "method": "emulate_tx",
+  "params": {
+    "signed_tx_base64": "DgAAAHNlbmRlci50ZXN0bmV0AOrmAai64SZOv9e/naX4W15pJx0GAap35wTT1T/DwcbbDwAAAAAAAAAQAAAAcmVjZWl2ZXIudGVzdG5ldNMnL7URB1cxPOu3G8jTqlEwlcasagIbKlAJlF5ywVFLAQAAAAMAAACh7czOG8LTAAAAAAAAAGQcOG03xVSFQFjoagOb4NBBqWhERnnz45LY4+52JgZhm1iQKz7qAdPByrGFDQhQ2Mfga8RlbysuQ8D8LlA6bQE=",
+    "wait_until": "INCLUDED_FINAL"
+  }
+}
+```
+or
+```json
+{
+  "jsonrpc": "2.0",
+  "id": "dontcare",
+  "method": "emulate_tx",
+  "params": [ "DgAAAHNlbmRlci50ZXN0bmV0AOrmAai64SZOv9e/naX4W15pJx0GAap35wTT1T/DwcbbDwAAAAAAAAAQAAAAcmVjZWl2ZXIudGVzdG5ldNMnL7URB1cxPOu3G8jTqlEwlcasagIbKlAJlF5ywVFLAQAAAAMAAACh7czOG8LTAAAAAAAAAGQcOG03xVSFQFjoagOb4NBBqWhERnnz45LY4+52JgZhm1iQKz7qAdPByrGFDQhQ2Mfga8RlbysuQ8D8LlA6bQE="
+  ]
+}
+```
+Response:
+```json
+{
+    "jsonrpc": "2.0",
+    "result": {
+        "block_height": 156743532,
+        "gas_price": 100000000,
+        "results": [
+            {
+                "Transfer": {
+                    "fee": 115123062500
+                }
+            }
+        ]
+    },
+    "id": "dontcare"
+}
+```

docs/CUSTOM_RPC_METHODS.md

@@ -1,7 +1,8 @@
 | **Method**                        | **status**    | **Note**                                                                    |
 |-----------------------------------|---------------|-----------------------------------------------------------------------------|
 | view_state_paginated              | Included      | Custom method. See details [here](../docs/CUSTOM_RPC_METHODS.md)            |
-| view_receipt_record               | Included      | Custom method. See details [here](../docs/CUSTOM_RPC_METHODS.md)            |
+| view_state_paginated              | Included      | Custom method. See details [here](../docs/CUSTOM_RPC_METHODS.md)            |
+| emulate_tx               | Included      | Custom method. See details [here](../docs/CUSTOM_RPC_METHODS.md)            |
 | query.view_account                | Included      |                                                                             |
 | query.view_code                   | Included      |                                                                             |
 | query.view_state                  | Included      |                                                                             |

docs/RPC_METHODS.md

@@ -46,6 +46,7 @@ near-jsonrpc.workspace = true
 near-jsonrpc-client.workspace = true
 near-indexer-primitives.workspace = true
 near-lake-framework.workspace = true
+node-runtime.workspace = true
 near-primitives.workspace = true
 near-parameters.workspace = true
 near-vm-runner.workspace = true

rpc-server/Cargo.toml

@@ -78,6 +78,13 @@ async fn rpc_handler(
             })
             .await
         }
+
+        "emulate_tx" => {
+            process_method_call(request, |params| {
+                modules::transactions::methods::emulate_tx(data, params)
+            })
+            .await
+        }
         // request methods
         "query" => {
             process_method_call(request, |params| {