feat(ljs:devices): add type narrowing helper isDeviceModelId

.changeset/polite-ladybugs-prove.md

@@ -0,0 +1,5 @@
+---
+"@ledgerhq/devices": patch
+---
+
+Add type narrowing helper isDeviceModelId

libs/ledgerjs/packages/devices/src/helpers.test.ts

@@ -1,5 +1,25 @@
 import { DeviceModelId } from ".";
-import { stringToDeviceModelId } from "./helpers";
+import { stringToDeviceModelId, isDeviceModelId } from "./helpers";
+
+
+const validDeviceModelsIds = ["nanoS", "nanoX", "blue", "nanoSP", "stax", "europa"];
+const invalidDeviceModelsIds = ["does-not-exist", "", null, undefined];
+
+describe("isDeviceModelId", () => {
+  validDeviceModelsIds.forEach(potentialModelId => {
+    test(`Input: ${potentialModelId} -> Expected output: true`, () => {
+      const result = isDeviceModelId(potentialModelId);
+      expect(result).toEqual(true);
+    });
+  });
+
+  invalidDeviceModelsIds.forEach(potentialModelId => {
+    test(`Input: ${potentialModelId} -> Expected output: false`, () => {
+      const result = isDeviceModelId(potentialModelId);
+      expect(result).toEqual(false);
+    });
+  });
+});
 
 type Test = {
   input: [string, DeviceModelId];

libs/ledgerjs/packages/devices/src/helpers.ts

@@ -1,12 +1,14 @@
 import { DeviceModelId } from ".";
 
+export function isDeviceModelId(val: string | undefined | null): val is DeviceModelId {
+  if (!val) return false;
+  return Object.values(DeviceModelId).includes(val as DeviceModelId);
+}
+
 export const stringToDeviceModelId = (
   strDeviceModelId: string,
   defaultDeviceModelId: DeviceModelId,
 ): DeviceModelId => {
-  if (Object.values(DeviceModelId)?.includes(strDeviceModelId as DeviceModelId)) {
-    return DeviceModelId[strDeviceModelId as DeviceModelId];
-  }
-
-  return defaultDeviceModelId;
+  if (!isDeviceModelId(strDeviceModelId)) return defaultDeviceModelId;
+  return DeviceModelId[strDeviceModelId];
 };