feat: add a function to verify and return Abilities.

Given a list of strings representing capability names (Abilities), verify that all the strings are valid Abilities and return Abilities[].

Abilities[] is still just a list of strings, but this helps us play nice with Typescript.

Inspired by #1250

packages/w3up-client/src/client.js

@@ -6,6 +6,7 @@ import {
 import {
   Store as StoreCapabilities,
   Upload as UploadCapabilities,
+  abilitiesAsStrings,
 } from '@web3-storage/capabilities'
 import { CAR } from '@ucanto/transport'
 import { Base } from './base.js'
@@ -54,6 +55,27 @@ export class Client extends Base {
     this.coupon = new CouponAPI(agentData, options)
   }
 
+  /**
+   * Verify and return Abilities.
+   * 
+   * Given a list of strings representing capability names (Abilities), 
+   * verify that all the strings are valid Abilities and return Abilities[].
+   * 
+   * Abilities[] is still just a list of strings, but this helps us play
+   * nice with Typescript.
+   * 
+   * @param {string[]} abilities
+   * @returns {import('@web3-storage/access').Abilities[]}
+   */
+  static abilities(abilities) {
+    for (const ability of abilities) {
+      if (!abilitiesAsStrings.includes(/** @type {import('@web3-storage/access').Abilities} */(ability))) {
+        throw new Error(`${ability} is not a supported capability`)
+      }
+    }
+    return /** @type {import('@web3-storage/access').Abilities[]} */(abilities)
+  }
+
   did() {
     return this._agent.did()
   }

packages/w3up-client/test/client.test.js

@@ -480,4 +480,17 @@ describe('Client', () => {
       assert.equal(typeof client.capability.upload.remove, 'function')
     })
   })
+
+  describe('abilities', () => {
+    it('should return the passed argument if all abilities are valid', async () => {
+      const abilities = ['store/add', 'upload/add']
+      assert.equal(Client.abilities(abilities), abilities)
+    })
+
+    it('should throw an error if one of the abilities is not supported', async () => {
+      assert.throws(() => {
+        Client.abilities(['foo/bar'])
+      })
+    })
+  })
 })