test: add test for deterministic encryption key

tests/specs/onboarding/onboarding.spec.ts

@@ -101,4 +101,27 @@ test.describe('Onboarding an existing user', () => {
       });
     });
   });
+
+  // Functionality is important for backwards compatibility with older wallet versions
+  test.describe('Encryption key values', () => {
+    test.beforeEach(async ({ extensionId, globalPage, onboardingPage }) => {
+      await globalPage.setupAndUseApiCalls(extensionId);
+      await onboardingPage.signInWithTestAccount(extensionId);
+    });
+
+    test('that the encryption key is generated correctly against a known working value', async ({
+      globalPage,
+    }) => {
+      const encryptionKey = await globalPage.page.evaluate(async () => {
+        const { encryptionKey } = await chrome.storage.session.get('encryptionKey');
+        return encryptionKey;
+      });
+
+      test
+        .expect(encryptionKey)
+        .toEqual(
+          'd904f412b8d116540017c302f3f7033813c95902af5a067c7befcc34fa5e5290709f157f80548603a1e4f8edc2c0d5d7'
+        );
+    });
+  });
 });