test: add anonymise unit tests (#3722)

Adds unit tests to `anonymise` functions. 

See:
https://github.com/Unleash/unleash/pull/3683#pullrequestreview-1418223563

src/lib/util/anonymise.test.ts

@@ -0,0 +1,132 @@
+import { anonymise, anonymiseKeys } from './anonymise';
+
+const REGEX_MATCH = /^[a-f0-9]{9}@unleash\.run$/;
+
+test('anonymise', () => {
+    expect(anonymise('test')).toMatch(REGEX_MATCH);
+});
+
+describe('anonymiseKeys', () => {
+    test.each([
+        null,
+        undefined,
+        true,
+        false,
+        'test',
+        123,
+        [1, 2, 3],
+        { test: 'test' },
+    ])(
+        'A parameter without keys (non-object, non-array) should return the same value',
+        (obj) => expect(anonymiseKeys(obj!, [])).toStrictEqual(obj),
+    );
+
+    test('An object should anonymise the specified keys', () => {
+        expect(
+            anonymiseKeys({ test: 'test', test2: 'test2' }, ['test']),
+        ).toStrictEqual({
+            test: expect.stringMatching(REGEX_MATCH),
+            test2: 'test2',
+        });
+    });
+
+    test('An array of objects should anonymise the specified keys', () => {
+        expect(
+            anonymiseKeys(
+                [
+                    { test: 'test', test2: 'test2' },
+                    { test: 'test', test2: 'test2' },
+                ],
+                ['test'],
+            ),
+        ).toStrictEqual([
+            { test: expect.stringMatching(REGEX_MATCH), test2: 'test2' },
+            { test: expect.stringMatching(REGEX_MATCH), test2: 'test2' },
+        ]);
+    });
+
+    test('A complex array/object should anonymise the specified keys, no matter the depth', () => {
+        expect(
+            anonymiseKeys(
+                [
+                    {
+                        test1: [],
+                        anon: 'secret',
+                        other: 'other',
+                        test2: {
+                            test3: 'test3',
+                            test4: [
+                                {
+                                    test5: {
+                                        anon2: 'secret2',
+                                    },
+                                },
+                            ],
+                        },
+                    },
+                    {
+                        test6: [
+                            {
+                                test7: [
+                                    {
+                                        test8: {
+                                            anon: 'secret3',
+                                            other2: 'other2',
+                                        },
+                                    },
+                                ],
+                                test9: {
+                                    other3: 'other3',
+                                    anon2: 'secret4',
+                                    test10: {
+                                        anon: 'secret5',
+                                    },
+                                },
+                                other4: 'other4',
+                            },
+                        ],
+                    },
+                ],
+                ['anon', 'anon2'],
+            ),
+        ).toStrictEqual([
+            {
+                test1: [],
+                anon: expect.stringMatching(REGEX_MATCH),
+                other: 'other',
+                test2: {
+                    test3: 'test3',
+                    test4: [
+                        {
+                            test5: {
+                                anon2: expect.stringMatching(REGEX_MATCH),
+                            },
+                        },
+                    ],
+                },
+            },
+            {
+                test6: [
+                    {
+                        test7: [
+                            {
+                                test8: {
+                                    anon: expect.stringMatching(REGEX_MATCH),
+                                    other2: 'other2',
+                                },
+                            },
+                        ],
+                        test9: {
+                            other3: 'other3',
+                            anon2: expect.stringMatching(REGEX_MATCH),
+                            test10: {
+                                anon: expect.stringMatching(REGEX_MATCH),
+                            },
+                        },
+                        other4: 'other4',
+                    },
+                ],
+            },
+        ]);
+    });
+});

src/lib/util/anonymise.ts

@@ -14,7 +14,7 @@ export function anonymiseKeys<T>(object: T, keys: string[]): T {
     }
 
     if (Array.isArray(object)) {
-        return object.map((item) => anonymiseKeys(item, keys)) as unknown as T;
+        return object.map((item) => anonymiseKeys(item, keys)) as T;
     } else {
         return Object.keys(object).reduce((result, key) => {
             if (