feat: add feature RPC (#2719)

* add feature RPC

* export, add tests

* update history

* fix test

* update models

* update feature models to correctly handle both cases

* fix models/tests

* fix test, improve type

* undo type change

* fix test

packages/xrpl/HISTORY.md

@@ -11,6 +11,7 @@ Subscribe to [the **xrpl-announce** mailing list](https://groups.google.com/g/xr
 ### Added
 * Add `nfts_by_issuer` clio-only API definition
 * Support for the `fixPreviousTxnID` amendment.
+* Support for the user version of the `feature` RPC.
 
 ## 3.1.0 (2024-06-03)
 

packages/xrpl/src/models/methods/feature.ts

@@ -0,0 +1,68 @@
+import { BaseRequest, BaseResponse } from './baseMethod'
+
+export interface FeatureAllRequest extends BaseRequest {
+  command: 'feature'
+
+  feature?: never
+}
+
+export interface FeatureOneRequest extends BaseRequest {
+  command: 'feature'
+
+  feature: string
+}
+
+/**
+ * The `feature` command returns information about amendments this server knows about, including whether they are enabled.
+ * Returns an {@link FeatureResponse}.
+ *
+ * @category Requests
+ */
+export type FeatureRequest = FeatureAllRequest | FeatureOneRequest
+
+export interface FeatureAllResponse extends BaseResponse {
+  result: {
+    features: Record<
+      string,
+      {
+        /*
+         * Whether this amendment is currently enabled in the latest ledger.
+         */
+        enabled: boolean
+
+        /*
+         * The human-readable name for this amendment, if known.
+         */
+        name: string
+
+        supported: boolean
+      }
+    >
+  }
+}
+
+export interface FeatureOneResponse extends BaseResponse {
+  result: Record<
+    string,
+    {
+      /*
+       * Whether this amendment is currently enabled in the latest ledger.
+       */
+      enabled: boolean
+
+      /*
+       * The human-readable name for this amendment, if known.
+       */
+      name: string
+
+      supported: boolean
+    }
+  >
+}
+
+/**
+ * Response expected from an {@link FeatureRequest}.
+ *
+ * @category Responses
+ */
+export type FeatureResponse = FeatureAllResponse | FeatureOneResponse

packages/xrpl/src/models/methods/index.ts

@@ -66,6 +66,14 @@ import {
   DepositAuthorizedRequest,
   DepositAuthorizedResponse,
 } from './depositAuthorized'
+import {
+  FeatureAllRequest,
+  FeatureAllResponse,
+  FeatureOneRequest,
+  FeatureOneResponse,
+  FeatureRequest,
+  FeatureResponse,
+} from './feature'
 import { FeeRequest, FeeResponse } from './fee'
 import {
   GatewayBalance,
@@ -214,6 +222,7 @@ type Request =
   | ServerDefinitionsRequest
   | ServerInfoRequest
   | ServerStateRequest
+  | FeatureRequest
   // utility methods
   | PingRequest
   | RandomRequest
@@ -271,6 +280,7 @@ type Response<Version extends APIVersion = typeof DEFAULT_API_VERSION> =
   | ServerDefinitionsResponse
   | ServerInfoResponse
   | ServerStateResponse
+  | FeatureResponse
   // utility methods
   | PingResponse
   | RandomResponse
@@ -419,6 +429,10 @@ export type RequestResponseMap<
   ? ServerStateResponse
   : T extends ServerDefinitionsRequest
   ? ServerDefinitionsResponse
+  : T extends FeatureAllRequest
+  ? FeatureAllResponse
+  : T extends FeatureOneRequest
+  ? FeatureOneResponse
   : T extends PingRequest
   ? PingResponse
   : T extends RandomRequest
@@ -591,6 +605,8 @@ export {
   ServerState,
   StateAccountingFinal,
   StateAccounting,
+  FeatureRequest,
+  FeatureResponse,
   // utility methods
   PingRequest,
   PingResponse,

packages/xrpl/test/integration/requests/feature.test.ts

@@ -0,0 +1,68 @@
+import { assert } from 'chai'
+
+import { FeatureRequest } from '../../../src'
+import serverUrl from '../serverUrl'
+import {
+  setupClient,
+  teardownClient,
+  type XrplIntegrationTestContext,
+} from '../setup'
+
+// how long before each test case times out
+const TIMEOUT = 20000
+const AMENDMENT =
+  '8CC0774A3BF66D1D22E76BBDA8E8A232E6B6313834301B3B23E8601196AE6455'
+
+describe('feature', function () {
+  let testContext: XrplIntegrationTestContext
+
+  beforeEach(async () => {
+    testContext = await setupClient(serverUrl)
+  })
+  afterEach(async () => teardownClient(testContext))
+
+  it(
+    'all',
+    async () => {
+      const featureRequest: FeatureRequest = {
+        command: 'feature',
+      }
+      const featureResponse = await testContext.client.request(featureRequest)
+
+      assert.equal(featureResponse.type, 'response')
+      assert.typeOf(featureResponse.result.features, 'object')
+      assert.isTrue(AMENDMENT in featureResponse.result.features)
+
+      const amendmentData = featureResponse.result.features[AMENDMENT]
+      assert.equal(amendmentData.name, 'AMM')
+      // TODO: rippled says "false" for standalone nodes for some reason
+      assert.typeOf(amendmentData.enabled, 'boolean')
+      assert.equal(amendmentData.supported, true)
+    },
+    TIMEOUT,
+  )
+
+  it(
+    'one',
+    async () => {
+      const featureRequest: FeatureRequest = {
+        command: 'feature',
+        feature: AMENDMENT,
+      }
+      const featureResponse = await testContext.client.request(featureRequest)
+
+      assert.equal(featureResponse.type, 'response')
+      assert.typeOf(featureResponse.result, 'object')
+      assert.isTrue(AMENDMENT in featureResponse.result)
+      assert.lengthOf(Object.keys(featureResponse.result), 1)
+
+      const amendmentData = featureResponse.result[AMENDMENT]
+
+      assert.equal(amendmentData.name, 'AMM')
+      // TODO: rippled says "false" for standalone nodes for some reason
+      assert.typeOf(amendmentData.enabled, 'boolean')
+      assert.equal(amendmentData.supported, true)
+    },
+    TIMEOUT,
+  )
+})