From e73251ad9261061f8b275e5ba5a783f1f7b85314 Mon Sep 17 00:00:00 2001
From: Duke <duke@hush.is>
Date: Tue, 14 Oct 2025 22:29:10 -0400
Subject: [PATCH] WIP donation test

---
 qa/rpc-tests/shieldcoinbase_donation.py | 75 ++++++++++++++++++++++++-
 1 file changed, 74 insertions(+), 1 deletion(-)

diff --git a/qa/rpc-tests/shieldcoinbase_donation.py b/qa/rpc-tests/shieldcoinbase_donation.py
index 672caf51d..42e6b7329 100755
--- a/qa/rpc-tests/shieldcoinbase_donation.py
+++ b/qa/rpc-tests/shieldcoinbase_donation.py
@@ -100,8 +100,81 @@ class ShieldCoinbaseDonationTest (BitcoinTestFramework):
 
     def run_test_custom_nondefault_fee(self):
         rpc    = self.nodes[0]
+        zaddr1 = rpc.z_getnewaddress()
+
+        donation = 5
 
         # donation zaddr is already imported from previous test
+        # NOTE: goal here is to test a situation where
+        # sendAmount/donationAmount arithmetic leads to a situation where the
+        # exact amount in satoshis must deal with truncation/rounding
+
+        # generate some new coinbase funds
+        rpc.generate(1)
+        self.sync_all()
+
+        # shield funds to a new zaddr in this wallet with non-default fee
+        fee = 0.00000001 # 1 puposhi fee will lead to some kind of rounding/truncation arithmetic
+        response = rpc.z_shieldcoinbase('*', zaddr1, fee, 1, donation)
+        opid = response['opid']
+        print("opid=" + opid)
+
+        shieldingValue = response['shieldingValue']
+        # sanity check
+        assert_greater_than_or_equal( shieldingValue ,  1.0 )
+
+        # TODO: this might not be enough time for slow machines, better
+        # solution would be to wait until the opid finishes
+        time.sleep(2) # give some time for the ztx to complete
+
+        # confirm tx from above
+        rpc.generate(1)
+        self.sync_all()
+
+        # get the txid
+        json = rpc.z_getoperationstatus()
+        # NOTE: this is index 1 because this test runs after the above test
+        # It would be better to specifically find the data for our opid
+        txid = json[1]['result']['txid']
+        print("txid=" + txid)
+
+        rpc.z_listunspent()
+
+        # (300000000 - 1)*.95
+        # 284999999.05
+        # (300000000 - 1)*.05
+        # 14999999.95
+        # The above value will be truncated (not rounded) by casting from
+        # double to CAmount/int64_t which means the donation will be 14999999
+        # and the sendAmount will be 300000000 - 14999999 = 285000001
+
+        expectedSendAmount     = 285000001
+        expectedDonationAmount = 14999999
+
+        # actually seeing this: 2.84990500 + 0.14999500 = 2.99990000
+        # logging: donation=5, sendAmount=299999999, donationAmount=14999999
+
+        # lookup txid
+        rawtx1 = rpc.z_viewtransaction(txid)
+
+        # TODO: set this up once for all tests since they all use the same zaddr
+        donation_zaddr   = "zregtestsapling1y30nwg0clsu6gcyrnvht8hdyfk3vwtszlh6kc4z5hv9hmpxzg2g0nx7c60xeecggm9x9gma96t4"
+
+        # there should be two outputs to different addresses, order is nondeterministic
+        if rawtx1['outputs'][0]['address'] == donation_zaddr:
+            donation_zout = 0
+            other_zout    = 1
+        else:
+            donation_zout = 1
+            other_zout    = 0
+
+        assert_equal( rawtx1['outputs'][donation_zout]['address'] , donation_zaddr, 'correct zaddr gets donation')
+        assert_equal( rawtx1['outputs'][donation_zout]['valueZat'] , expectedDonationAmount, '5% donation sends correct donationAmount')
+
+        assert_equal( rawtx1['outputs'][other_zout]['address'] , zaddr1, 'correct zaddr gets main amount')
+        assert_equal( rawtx1['outputs'][other_zout]['valueZat'] , expectedSendAmount, '5% donation sends correct sendAmount')
+
+        #TODO: assert sum = 3
 
     def run_test_custom(self):
         rpc    = self.nodes[0]
@@ -149,7 +222,7 @@ class ShieldCoinbaseDonationTest (BitcoinTestFramework):
         # (3 - fee)*0.05
         expectedAmount1 = 14999500
 
-        # lookup txid on node1 which should have received donation
+        # lookup txid
         rawtx1 = rpc.z_viewtransaction(txid)
         # there should be two outputs to different addresses, order is nondeterministic
         if rawtx1['outputs'][0]['address'] == testing_zaddr: