refactor(connect): add coin symbol cast helper

Author: peter-sanderson

packages/connect-common/src/types/coinInfo.ts

@@ -179,6 +179,8 @@ export const coinSymbols = [
 // A supported coin symbol, e.g. `'btc'` / `'ada'`. See `coinSymbols`.
 export type CoinSymbol = (typeof coinSymbols)[number];
 
+export const asCoinSymbol = (value: string): CoinSymbol => value as CoinSymbol;
+
 const coinSymbolSet: ReadonlySet<string> = new Set(coinSymbols);
 
 // Runtime validation for `CoinSymbol`, derived from the same `coinSymbols` source as the type.

packages/connect/src/core/AbstractMethod.ts

@@ -1,4 +1,4 @@
-import { ERRORS, UI_REQUEST } from '@trezor/connect-common';
+import { ERRORS, UI_REQUEST, asCoinSymbol } from '@trezor/connect-common';
 import type {
     CallMethodPayload,
     CallMethodResponse,
@@ -143,7 +143,7 @@ export abstract class AbstractMethod<Name extends CallMethodPayload['method'], P
     // to a known `CoinSymbol` (both derive from the same coin definitions), so
     // the cast is sound.
     private toCoinSymbol(shortcut: string): CoinSymbol {
-        return shortcut.toLowerCase() as CoinSymbol;
+        return asCoinSymbol(shortcut.toLowerCase());
     }
 
     // Build a `PermissionRequest` for a single coin (or coin-less when `coin` is

packages/connect/src/data/coinInfo.ts

@@ -1,11 +1,12 @@
 // origin: https://github.com/trezor/connect/blob/develop/src/js/data/CoinInfo.js
 import { ERRORS } from '@trezor/connect-common/src/constants';
-import type {
-    BitcoinNetworkInfo,
-    CoinInfo,
-    CoinSymbol,
-    EthereumNetworkInfo,
-    MiscNetworkInfo,
+import {
+    type BitcoinNetworkInfo,
+    type CoinInfo,
+    type CoinSymbol,
+    type EthereumNetworkInfo,
+    type MiscNetworkInfo,
+    asCoinSymbol,
 } from '@trezor/connect-common/src/types/coinInfo';
 import coinsEth from '@trezor/connect-data/files/coins-eth.json';
 import coins from '@trezor/connect-data/files/coins.json';
@@ -121,7 +122,7 @@ const getCoinInfo = (coin: CoinSymbol) =>
 
 export const getCoinInfoOrThrow = (coin: string): Readonly<CoinInfo> => {
     // `coin` is unvalidated caller input; a non-shortcut resolves to undefined below
-    const coinInfo = getCoinInfo(coin as CoinSymbol);
+    const coinInfo = getCoinInfo(asCoinSymbol(coin));
     if (!coinInfo) {
         throw ERRORS.TypedError('Method_UnknownCoin');
     }

packages/connect/src/utils/addressUtils.test.ts

@@ -1,4 +1,4 @@
-import type { CoinSymbol } from '@trezor/connect-common/src/types/coinInfo';
+import { asCoinSymbol } from '@trezor/connect-common';
 
 import * as fixtures from './__fixtures__/addressUtils';
 import * as utils from './addressUtils';
@@ -9,15 +9,15 @@ describe('utils/addressUtils', () => {
         fixtures.validAddresses.forEach(f => {
             it(`${f.description} ${f.address}`, () => {
                 expect(
-                    utils.isValidAddress(f.address, getBitcoinNetwork(f.coin as CoinSymbol)!),
+                    utils.isValidAddress(f.address, getBitcoinNetwork(asCoinSymbol(f.coin))!),
                 ).toEqual(true);
             });
         });
 
         fixtures.invalidAddresses.forEach(f => {
             it(`Invalid ${f.coin} ${f.address}`, () => {
                 expect(
-                    utils.isValidAddress(f.address, getBitcoinNetwork(f.coin as CoinSymbol)!),
+                    utils.isValidAddress(f.address, getBitcoinNetwork(asCoinSymbol(f.coin))!),
                 ).toEqual(false);
             });
         });

suite-common/connect-popup/src/permissions.ts

@@ -4,6 +4,7 @@ import {
     type EnabledNetwork,
     GRANTABLE_PERMISSIONS,
     type PermissionRequest,
+    asCoinSymbol,
     isCoinSymbol,
 } from '@trezor/connect';
 import { unique } from '@trezor/utils/src/unique';
@@ -108,7 +109,7 @@ export const canonicalizePermissionCoins = (
     permissions.map(permission =>
         permission.coin === undefined
             ? permission
-            : { ...permission, coin: permission.coin.toLowerCase() as CoinSymbol },
+            : { ...permission, coin: asCoinSymbol(permission.coin.toLowerCase()) },
     );
 
 // Union two permission lists, de-duplicated by (permission, coin). `base` comes first, so on a