chore: scaffold verify gas usage [TEMP]

Author: rictorlome

src/vms/pvm/etna-builder/spend-reducers/index.ts

@@ -2,5 +2,6 @@ export { handleFeeAndChange } from './handleFeeAndChange';
 export { useSpendableLockedUTXOs } from './useSpendableLockedUTXOs';
 export { useUnlockedUTXOs } from './useUnlockedUTXOs';
 export { verifyAssetsConsumed } from './verifyAssetsConsumed';
+export { verifyGasUsage } from './verifyGasUsage';
 
 export type * from './types';

src/vms/pvm/etna-builder/spend-reducers/verifyGasUsage.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, test, vi } from 'vitest';
+import { testContext } from '../../../../fixtures/context';
+import { getInitialReducerState, getSpendHelper } from './fixtures/reducers';
+import { verifyGasUsage } from './verifyGasUsage';
+
+describe('verifyGasUsage', () => {
+  test('returns original state if gas is under the threshold', () => {
+    const initialState = getInitialReducerState();
+    const spendHelper = getSpendHelper();
+    const spy = vi.spyOn(spendHelper, 'verifyAssetsConsumed');
+
+    const state = verifyAssetsConsumed(initialState, spendHelper, testContext);
+
+    expect(state).toBe(initialState);
+    expect(spy).toHaveBeenCalledTimes(1);
+  });
+
+  test('throws an error if gas is over the threshold', () => {
+    const initialState = getInitialReducerState();
+    const spendHelper = getSpendHelper();
+
+    // Mock the verifyAssetsConsumed method to throw an error
+    // Testing for this function can be found in the spendHelper.test.ts file
+    spendHelper.verifyAssetsConsumed = vi.fn(() => {
+      throw new Error('Test error');
+    });
+
+    expect(() =>
+      verifyAssetsConsumed(initialState, spendHelper, testContext),
+    ).toThrow('Test error');
+  });
+});

src/vms/pvm/etna-builder/spend-reducers/verifyGasUsage.ts

@@ -0,0 +1,19 @@
+import type { SpendReducerFunction } from './types';
+
+/**
+ * Verify that gas usage is within limits.
+ *
+ * Calls the spendHelper's verifyGasUsage method.
+ */
+export const verifyGasUsage: SpendReducerFunction = (
+  state,
+  spendHelper,
+) => {
+  const verifyError = spendHelper.verifyGasUsage();
+
+  if (verifyError) {
+    throw verifyError;
+  }
+
+  return state;
+};

src/vms/pvm/etna-builder/spend.test.ts

@@ -4,6 +4,7 @@ import { Address, OutputOwners } from '../../../serializable';
 import { createDimensions } from '../../common/fees/dimensions';
 import {
   verifyAssetsConsumed,
+  verifyGasUsage,
   type SpendReducerFunction,
   type SpendReducerState,
   handleFeeAndChange,
@@ -14,6 +15,7 @@ import { feeState as testFeeState } from '../../../fixtures/pvm';
 import { bech32ToBytes } from '../../../utils';
 
 vi.mock('./spend-reducers', () => ({
+  verifyGasUsage: vi.fn<SpendReducerFunction>((state) => state),
   verifyAssetsConsumed: vi.fn<SpendReducerFunction>((state) => state),
   handleFeeAndChange: vi.fn<SpendReducerFunction>((state) => state),
 }));
@@ -51,6 +53,7 @@ describe('./src/vms/pvm/etna-builder/spend.test.ts', () => {
 
     expect(testReducer).toHaveBeenCalledTimes(1);
     expect(verifyAssetsConsumed).toHaveBeenCalledTimes(1);
+    expect(verifyGasUsage).toHaveBeenCalledTimes(1);
     expect(handleFeeAndChange).toHaveBeenCalledTimes(1);
   });
 

src/vms/pvm/etna-builder/spend.ts

@@ -9,7 +9,7 @@ import type { Dimensions } from '../../common/fees/dimensions';
 import type { Context } from '../../context';
 import type { FeeState } from '../models';
 import type { SpendReducerFunction, SpendReducerState } from './spend-reducers';
-import { handleFeeAndChange, verifyAssetsConsumed } from './spend-reducers';
+import { handleFeeAndChange, verifyAssetsConsumed, verifyGasUsage } from './spend-reducers';
 import { SpendHelper } from './spendHelper';
 
 type SpendResult = Readonly<{
@@ -145,6 +145,7 @@ export const spend = (
       ...spendReducers,
       verifyAssetsConsumed,
       handleFeeAndChange,
+      verifyGasUsage // This should happen after change is added
       // Consolidation and sorting happens in the SpendHelper.
     ];
 

src/vms/pvm/etna-builder/spendHelper.ts

@@ -218,13 +218,13 @@ export class SpendHelper {
   }
 
   /**
-   * Calculates the fee for the SpendHelper based on its complexity and gas price.
+   * Calculates the gas usage for the SpendHelper based on its complexity and the weights.
    * Provide an empty change output as a parameter to calculate the fee as if the change output was already added.
    *
    * @param {TransferableOutput} additionalOutput - The change output that has not yet been added to the SpendHelper.
-   * @returns {bigint} The fee for the SpendHelper.
+   * @returns {bigint} The gas usage for the SpendHelper.
    */
-  calculateFee(additionalOutput?: TransferableOutput): bigint {
+  private calculateGas(additionalOutput?: TransferableOutput): bigint {
     this.consolidateOutputs();
 
     const gas = dimensionsToGas(
@@ -234,6 +234,19 @@ export class SpendHelper {
       this.weights,
     );
 
+    return gas;
+  }
+
+  /**
+   * Calculates the fee for the SpendHelper based on its complexity and gas price.
+   * Provide an empty change output as a parameter to calculate the fee as if the change output was already added.
+   *
+   * @param {TransferableOutput} additionalOutput - The change output that has not yet been added to the SpendHelper.
+   * @returns {bigint} The fee for the SpendHelper.
+   */
+  calculateFee(additionalOutput?: TransferableOutput): bigint {
+    const gas = this.calculateGas(additionalOutput);
+
     const gasPrice = this.feeState.price;
 
     return gas * gasPrice;
@@ -283,6 +296,20 @@ export class SpendHelper {
 
     return null;
   }
+  
+  /**
+   * Verifies that gas usage does not exceed the fee state maximum.
+   *
+   * @returns {Error | null} An error if gas usage exceeds maximum, null otherwise.
+   */
+  verifyGasUsage(): Error | null {
+    const gas = this.calculateGas();
+    if (this.feeState.capacity <= gas) {
+      return new Error(`Gas usage of transaction (${gas.toString()}) exceeds capacity (${this.feeState.capacity.toString()})`)
+    }
+
+    return null;
+  }
 
   /**
    * Gets the inputs, outputs, and UTXOs for the SpendHelper.