fix(sdk-lib-mpc): use MPSUtil.executeTillRound in derive tests

TICKET: WCI-390
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Marzooqa

modules/sdk-lib-mpc/test/unit/tss/eddsa/derive.ts

@@ -1,7 +1,8 @@
 import assert from 'assert';
 import { ed25519 } from '@noble/curves/ed25519';
+import { EddsaMPSDsg, MPSUtil } from '../../../../src/tss/eddsa-mps';
 import { deriveUnhardenedMps } from '../../../../src/tss/eddsa-mps/derive';
-import { generateEdDsaDKGKeyShares, runEdDsaDSG } from './util';
+import { generateEdDsaDKGKeyShares } from './util';
 
 const MESSAGE = Buffer.from('The Times 03/Jan/2009 Chancellor on brink of second bailout for banks');
 
@@ -63,28 +64,40 @@ describe('deriveUnhardenedMps', function () {
   });
 
   describe('DSG signature cross-check against the public key derived by deriveUnhardenedMps', function () {
+    let sigAtRoot: Buffer;
+    let sigAtM0: Buffer;
+    let sigAtM01: Buffer;
+
+    before(function () {
+      const dsgA1 = new EddsaMPSDsg.DSG(0);
+      MPSUtil.executeTillRound(3, dsgA1, new EddsaMPSDsg.DSG(2), userKeyShare, bitgoKeyShare, MESSAGE, 'm');
+      sigAtRoot = dsgA1.getSignature();
+
+      const dsgA2 = new EddsaMPSDsg.DSG(0);
+      MPSUtil.executeTillRound(3, dsgA2, new EddsaMPSDsg.DSG(2), userKeyShare, bitgoKeyShare, MESSAGE, 'm/0');
+      sigAtM0 = dsgA2.getSignature();
+
+      const dsgA3 = new EddsaMPSDsg.DSG(0);
+      MPSUtil.executeTillRound(3, dsgA3, new EddsaMPSDsg.DSG(2), userKeyShare, bitgoKeyShare, MESSAGE, 'm/0/1');
+      sigAtM01 = dsgA3.getSignature();
+    });
+
     it('signature from DSG at "m" verifies against the root public key', function () {
-      const { dsgA } = runEdDsaDSG(userKeyShare, bitgoKeyShare, 0, 2, MESSAGE, 'm');
-      const sig = dsgA.getSignature();
-      assert(ed25519.verify(sig, MESSAGE, rootPubKey), 'DSG at "m" should verify against the raw DKG public key');
+      assert(ed25519.verify(sigAtRoot, MESSAGE, rootPubKey), 'DSG at "m" should verify against the raw DKG public key');
     });
 
     it('signature from DSG at "m/0" verifies against deriveUnhardenedMps(commonKeychain, "m/0")', function () {
       const derivedPk = Buffer.from(deriveUnhardenedMps(commonKeychain, 'm/0').slice(0, 64), 'hex');
-      const { dsgA } = runEdDsaDSG(userKeyShare, bitgoKeyShare, 0, 2, MESSAGE, 'm/0');
-      const sig = dsgA.getSignature();
       assert(
-        ed25519.verify(sig, MESSAGE, derivedPk),
+        ed25519.verify(sigAtM0, MESSAGE, derivedPk),
         'DSG at "m/0" should verify against deriveUnhardenedMps result at "m/0"'
       );
     });
 
     it('signature from DSG at "m/0/1" verifies against deriveUnhardenedMps(commonKeychain, "m/0/1")', function () {
       const derivedPk = Buffer.from(deriveUnhardenedMps(commonKeychain, 'm/0/1').slice(0, 64), 'hex');
-      const { dsgA } = runEdDsaDSG(userKeyShare, bitgoKeyShare, 0, 2, MESSAGE, 'm/0/1');
-      const sig = dsgA.getSignature();
       assert(
-        ed25519.verify(sig, MESSAGE, derivedPk),
+        ed25519.verify(sigAtM01, MESSAGE, derivedPk),
         'DSG at "m/0/1" should verify against deriveUnhardenedMps result at "m/0/1"'
       );
     });