more testing for change of owners and threshold atomic function

tests/multisigChangeThresholdTest.ts

@@ -370,6 +370,81 @@ describe("Test changing multisig threshold", async () => {
     );
   });
 
+  it("should not allow threshold to be changed by non multisig signer", async () => {
+    const ownerA = Keypair.generate();
+    const ownerB = Keypair.generate();
+    const ownerC = Keypair.generate();
+    const owners = [ownerA.publicKey, ownerB.publicKey, ownerC.publicKey];
+    const multisigSize = 200; // Big enough.
+    const threshold = new BN(2);
+
+    const multisig: MultisigAccount = await dsl.createMultisig(
+      owners,
+      multisigSize,
+      threshold
+    );
+
+    const newOwnerA = Keypair.generate();
+    const newOwnerB = Keypair.generate();
+    const newOwnerC = Keypair.generate();
+    const newOwners = [
+      newOwnerA.publicKey,
+      newOwnerB.publicKey,
+      newOwnerC.publicKey,
+    ];
+
+    try {
+      // Attempt to change the multisig threshold
+      await program.methods
+        .changeThreshold(new BN(1))
+        .accounts({
+          multisig: multisig.address,
+          multisigSigner: multisig.signer,
+        })
+        .rpc();
+      fail("Should have failed to execute transaction");
+    } catch (e) {
+      assert.ok(e.message.includes("Signature verification failed"));
+    }
+
+    try {
+      // Attempt to change the multisig threshold with provider key as signer
+      await program.methods
+        .changeThreshold(new BN(1))
+        .accounts({
+          multisig: multisig.address,
+          multisigSigner: provider.publicKey,
+        })
+        .rpc();
+      fail("Should have failed to execute transaction");
+    } catch (e) {
+      assert.ok(
+        e.message.includes(
+          "Error Code: ConstraintSeeds. Error Number: 2006. Error Message: A seeds constraint was violated"
+        )
+      );
+    }
+
+    try {
+      // Attempt to change the multisig threshold with an owner key as signer
+      await program.methods
+        .changeThreshold(new BN(1))
+        .accounts({
+          multisig: multisig.address,
+          multisigSigner: ownerA.publicKey,
+        })
+        .signers([ownerA])
+        .rpc();
+      fail("Should have failed to execute transaction");
+    } catch (e) {
+      assert.ok(
+        e.message.includes(
+          "Error Code: ConstraintSeeds. Error Number: 2006. Error Message: A seeds constraint was violated"
+        )
+      );
+    }
+  });
+
   // Threshold is of type u64, BN(-1) will actually be interpreted as 1
   it("ignores negatives on updated threshold", async () => {
     const ownerA = Keypair.generate();