addressed review comments.

Author: prameshj

packages/auth/src/api/account_management/mfa.test.ts

@@ -91,7 +91,7 @@ describe('api/account_management/startEnrollPhoneMfa', () => {
 
     await expect(startEnrollPhoneMfa(auth, request)).to.be.rejectedWith(
       FirebaseError,
-      "Firebase: This user's credential isn't valid for this project. This can happen if the user's token has been tampered with, or if the user isn't for the project associated with this API key. (auth/invalid-user-token)."
+      'auth/invalid-user-token'
     );
     expect(mock.calls[0].request).to.eql(request);
   });
@@ -155,7 +155,7 @@ describe('api/account_management/finalizeEnrollPhoneMfa', () => {
 
     await expect(finalizeEnrollPhoneMfa(auth, request)).to.be.rejectedWith(
       FirebaseError,
-      'Firebase: The verification ID used to create the phone auth credential is invalid. (auth/invalid-verification-id).'
+      'auth/invalid-verification-id'
     );
     expect(mock.calls[0].request).to.eql(request);
   });
@@ -225,7 +225,7 @@ describe('api/account_management/startEnrollTotpMfa', () => {
 
     await expect(startEnrollTotpMfa(auth, request)).to.be.rejectedWith(
       FirebaseError,
-      "Firebase: This user's credential isn't valid for this project. This can happen if the user's token has been tampered with, or if the user isn't for the project associated with this API key. (auth/invalid-user-token)."
+      'auth/invalid-user-token'
     );
     expect(mock.calls[0].request).to.eql(request);
   });

packages/auth/src/mfa/assertions/totp.test.ts

@@ -53,7 +53,7 @@ describe('core/mfa/assertions/totp/TotpMultiFactorGenerator', () => {
   describe('assertionForEnrollment', () => {
     it('should generate a valid TOTP assertion for enrollment', async () => {
       auth = await testAuth();
-      const secret = TotpSecret.fromStartTotpMfaEnrollmentResponse(
+      const secret = TotpSecret._fromStartTotpMfaEnrollmentResponse(
         startEnrollmentResponse,
         auth
       );
@@ -149,7 +149,7 @@ describe('core/mfa/totp/assertions/TotpMultiFactorAssertionImpl', () => {
   beforeEach(async () => {
     mockFetch.setUp();
     auth = await testAuth();
-    secret = TotpSecret.fromStartTotpMfaEnrollmentResponse(
+    secret = TotpSecret._fromStartTotpMfaEnrollmentResponse(
       startEnrollmentResponse,
       auth
     );
@@ -223,7 +223,7 @@ describe('core/mfa/assertions/totp/TotpSecret', async () => {
   const fakeAppName: AppName = 'test-app';
   const fakeEmail: string = 'user@email';
   const auth = await testAuth();
-  const secret = TotpSecret.fromStartTotpMfaEnrollmentResponse(
+  const secret = TotpSecret._fromStartTotpMfaEnrollmentResponse(
     serverResponse,
     auth
   );

packages/auth/src/mfa/assertions/totp.ts

@@ -95,7 +95,7 @@ export class TotpMultiFactorGenerator {
       idToken: mfaSession.credential,
       totpEnrollmentInfo: {}
     });
-    return TotpSecret.fromStartTotpMfaEnrollmentResponse(
+    return TotpSecret._fromStartTotpMfaEnrollmentResponse(
       response,
       mfaSession.auth
     );
@@ -119,25 +119,20 @@ export class TotpMultiFactorAssertionImpl
     super(FactorId.TOTP);
   }
 
+  /** @internal */
   static _fromSecret(
     secret: TotpSecret,
     otp: string
   ): TotpMultiFactorAssertionImpl {
-    return new TotpMultiFactorAssertionImpl(
-      (otp = otp),
-      undefined,
-      (secret = secret)
-    );
+    return new TotpMultiFactorAssertionImpl(otp, undefined, secret);
   }
 
+  /** @internal */
   static _fromEnrollmentId(
     enrollmentId: string,
     otp: string
   ): TotpMultiFactorAssertionImpl {
-    return new TotpMultiFactorAssertionImpl(
-      (otp = otp),
-      (enrollmentId = enrollmentId)
-    );
+    return new TotpMultiFactorAssertionImpl(otp, enrollmentId);
   }
 
   /** @internal */
@@ -154,7 +149,7 @@ export class TotpMultiFactorAssertionImpl
     return finalizeEnrollTotpMfa(auth, {
       idToken,
       displayName,
-      totpVerificationInfo: this.secret.makeTotpVerificationInfo(this.otp)
+      totpVerificationInfo: this.secret._makeTotpVerificationInfo(this.otp)
     });
   }
 
@@ -194,7 +189,8 @@ export class TotpSecret {
     private readonly auth: AuthInternal
   ) {}
 
-  static fromStartTotpMfaEnrollmentResponse(
+  /** @internal */
+  static _fromStartTotpMfaEnrollmentResponse(
     response: StartTotpMfaEnrollmentResponse,
     auth: AuthInternal
   ): TotpSecret {
@@ -209,7 +205,8 @@ export class TotpSecret {
     );
   }
 
-  makeTotpVerificationInfo(otp: string): TotpVerificationInfo {
+  /** @internal */
+  _makeTotpVerificationInfo(otp: string): TotpVerificationInfo {
     return { sessionInfo: this.sessionInfo, verificationCode: otp };
   }
 
@@ -240,6 +237,7 @@ export class TotpSecret {
   }
 }
 
+/** @internal */
 function _isEmptyString(input?: string): boolean {
   return typeof input === 'undefined' || input?.length === 0;
 }