fixed isJWKMetadata function

src/jwk-fetcher.ts

@@ -1,6 +1,6 @@
 import type { JsonWebKeyWithKid } from './jwt-decoder';
 import type { KeyStorer } from './key-store';
-import { isArray, isNonNullObject, isURL } from './validator';
+import { isNonNullObject, isObject, isURL } from './validator';
 
 export interface KeyFetcher {
   fetchPublicKeys(): Promise<Array<JsonWebKeyWithKid>>;
@@ -10,8 +10,19 @@ interface JWKMetadata {
   keys: Array<JsonWebKeyWithKid>;
 }
 
-export const isJWKMetadata = (value: any): value is JWKMetadata => 
-  isNonNullObject(value) && !!value.keys && isArray(value.keys);
+export const isJWKMetadata = (value: any): value is JWKMetadata => {
+  if (!isNonNullObject(value) || !value.keys) {
+    return false
+  }
+  const keys = value.keys
+  if (!Array.isArray(keys)) {
+    return false
+  }
+  const filtered = keys.filter((key): key is JsonWebKeyWithKid => 
+    isObject(key) && !!key.kid && typeof key.kid === 'string'
+  )
+  return keys.length === filtered.length
+}
 
 /**
  * Class to fetch public keys from a client certificates URL.

src/validator.ts

@@ -70,16 +70,6 @@ export function isNonEmptyString(value: any): value is string {
   return isString(value) && value !== '';
 }
 
-/**
- * Validates that a value is an array.
- *
- * @param value - The value to validate.
- * @returns Whether the value is an array or not.
- */
-export function isArray<T>(value: any): value is T[] {
-  return Array.isArray(value);
-}
-
 /**
    * 
 /**
@@ -89,7 +79,7 @@ export function isArray<T>(value: any): value is T[] {
  * @returns Whether the value is an object or not.
  */
 export function isObject(value: any): boolean {
-  return typeof value === 'object' && !isArray(value);
+  return typeof value === 'object' && !Array.isArray(value);
 }
 
 /**

tests/jwk-fetcher.test.ts

@@ -186,10 +186,20 @@ describe('isJWKMetadata', () => {
     expect(isJWKMetadata(invalidJWKMetadata)).toBe(false);
   });
 
-  it('should return false for object with non-array keys property', () => {
-    const invalidJWKMetadata = {
-      keys: 'notArray',
-    };
-    expect(isJWKMetadata(invalidJWKMetadata)).toBe(false);
+  it('returns false if keys is not an array', () => {
+    expect(isJWKMetadata({ keys: {} })).toBe(false);
+    expect(isJWKMetadata({ keys: 'string' })).toBe(false);
+  });
+
+  it('returns false if keys is an array but its elements do not have a kid property', () => {
+    expect(isJWKMetadata({ keys: [{}] })).toBe(false);
+  });
+
+  it('returns false if keys is an array but kid is not a string', () => {
+    expect(isJWKMetadata({ keys: [{ kid: 123 }] })).toBe(false);
+  });
+
+  it('returns false if only some keys have a kid property that is a string', () => {
+    expect(isJWKMetadata({ keys: [{ kid: 'string' }, {}] })).toBe(false);
   });
 });

tests/validator.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from 'vitest';
-import { isArray, isNonEmptyString, isNonNullObject, isNumber, isObject, isString, isURL } from '../src/validator';
+import { isNonEmptyString, isNonNullObject, isNumber, isObject, isString, isURL } from '../src/validator';
 
 describe('validator', () => {
   describe('isURL', () => {
@@ -76,22 +76,6 @@ describe('validator', () => {
     });
   });
 
-  describe('isArray', () => {
-    describe('non-array', () => {
-      const nonArrays = [undefined, null, NaN, 0, 1, '', 'a', true, false, {}, { a: 1 }];
-      nonArrays.forEach(v => {
-        it(`${v}`, () => expect(isArray(v)).toBeFalsy());
-      });
-    });
-
-    describe('array', () => {
-      const arrays = [[], [1, 2, 3], [], [1, 2, 3]];
-      arrays.forEach(v => {
-        it(`${v}`, () => expect(isArray(v)).toBeTruthy());
-      });
-    });
-  });
-
   describe('isObject', () => {
     describe('non-object', () => {
       const nonObjects = [undefined, NaN, 0, 1, true, false, '', 'a', [], ['a']];