Pkce challenge code empty (#221)

* Fixing empty challenge code problem

* Adding test for bufferToBase64UrlEncoded method

* fix ie11 'digest' call

__tests__/utils.test.ts

@@ -151,6 +151,25 @@ describe('utils', () => {
       const result = await sha256('test');
       expect(result).toBe(true);
     });
+    it('handles ie11 digest.result scenario', async () => {
+      (<any>global).crypto = {
+        subtle: {
+          digest: jest.fn((alg, encoded) => {
+            expect(alg).toMatchObject({ name: 'SHA-256' });
+            expect(Array.from(encoded)).toMatchObject([116, 101, 115, 116]);
+            return { result: true };
+          })
+        }
+      };
+      const result = await sha256('test');
+      expect(result).toBe(true);
+    });
+  });
+  describe('bufferToBase64UrlEncoded ', () => {
+    it('generates correct base64 encoded value from a buffer', async () => {
+      const result = await bufferToBase64UrlEncoded([116, 101, 115, 116]);
+      expect(result).toBe('dGVzdA');
+    });
   });
   describe('openPopup', () => {
     it('opens the popup', () => {

src/utils.ts

@@ -108,8 +108,22 @@ export const createQueryParams = (params: any) => {
     .join('&');
 };
 
-export const sha256 = (s: string) =>
-  window.crypto.subtle.digest({ name: 'SHA-256' }, new TextEncoder().encode(s));
+export const sha256 = async (s: string) => {
+  const response = await Promise.resolve(
+    window.crypto.subtle.digest(
+      { name: 'SHA-256' },
+      new TextEncoder().encode(s)
+    )
+  );
+  // msCrypto (IE11) uses the old spec, which is not Promise based
+  // https://msdn.microsoft.com/en-us/expression/dn904640(v=vs.71)
+  // Instead of returning a promise, it returns a CryptoOperation
+  // with a `result` property in it
+  if ((<any>response).result) {
+    return (<any>response).result;
+  }
+  return response;
+};
 
 const urlEncodeB64 = (input: string) => {
   const b64Chars = { '+': '-', '/': '_', '=': '' };
@@ -131,7 +145,7 @@ export const urlDecodeB64 = (input: string) =>
   decodeB64(input.replace(/_/g, '/').replace(/-/g, '+'));
 
 export const bufferToBase64UrlEncoded = input => {
-  const ie11SafeInput = new Uint8Array(Array.from(input));
+  const ie11SafeInput = new Uint8Array(input);
   return urlEncodeB64(
     window.btoa(String.fromCharCode(...Array.from(ie11SafeInput)))
   );