Add persistent Sprout test data.

This is in preparation for removing the ability to generate
Sprout outputs from z_shieldcoinbase. Once that is complete,
we will no longer be able to use `z_shieldcoinbase` for test
setup for uses of Sprout funds; instead, the persisted blockchain
state created in this commit will be used for tests that require
the use of Sprout funds.

This brings the test framework into line with how Sprout funds
are now used on mainnet and testnet; existing Sprout funds may
be spent, and Sprout change may be created, but no funds may
be transfered into the Sprout pool, since the activation of
ZIP 211.

qa/pull-tester/rpc-tests.py

@@ -43,6 +43,7 @@ BASE_SCRIPTS= [
     'sprout_sapling_migration.py',
     'remove_sprout_shielding.py',
     'zcjoinsplitdoublespend.py',
+    'create_sprout_chains.py',
     # vv Tests less than 2m vv
     'zcjoinsplit.py',
     'mergetoaddress_mixednotes.py',

qa/rpc-tests/create_sprout_chains.py

@@ -0,0 +1,98 @@
+#!/usr/bin/env python3
+# Copyright (c) 2022 The Zcash developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or https://www.opensource.org/licenses/mit-license.php .
+
+from decimal import Decimal
+import json
+import os.path
+import shutil
+import tarfile
+import time
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    start_nodes, stop_nodes,
+    get_coinbase_address, assert_equal,
+    set_node_times,
+    wait_and_assert_operationid_status,
+    wait_bitcoinds,
+    PRE_BLOSSOM_BLOCK_TARGET_SPACING
+)
+
+class CreateSproutChainsTest(BitcoinTestFramework):
+    def __init__(self):
+        super().__init__()
+        self.num_nodes = 4
+        self.is_network_split = False
+        self.setup_clean_chain = True
+
+    def setup_nodes(self):
+        return start_nodes(self.num_nodes, self.options.tmpdir, extra_args=[[
+            '-nuparams=5ba81b19:1', # Overwinter
+            '-nuparams=76b809bb:1', # Sapling
+        ]] * self.num_nodes)
+
+    def run_test (self):
+        block_time = int(time.time()) - (200 * PRE_BLOSSOM_BLOCK_TARGET_SPACING)
+        for i in range(2):
+            for peer in range(4):
+                for j in range(25 - i):
+                    set_node_times(self.nodes, block_time)
+                    self.nodes[peer].generate(1)
+                    self.sync_all()
+                    block_time += PRE_BLOSSOM_BLOCK_TARGET_SPACING
+
+                self.sync_all()
+
+                # On the second iteration, shield 50 mature ZEC to Sprout on each node
+                if i == 1:
+                    set_node_times(self.nodes, block_time)
+                    sprout_addr = self.nodes[peer].z_getnewaddress('sprout')
+                    op_result = self.nodes[peer].z_shieldcoinbase('*', sprout_addr, 0, 5)
+                    wait_and_assert_operationid_status(self.nodes[peer], op_result['opid'])
+
+                    self.nodes[peer].generate(1)
+                    self.sync_all()
+
+                    assert_equal(self.nodes[peer].z_getbalance(sprout_addr), Decimal('50'))
+
+        # Shut down the nodes
+        stop_nodes(self.nodes)
+        wait_bitcoinds()
+
+        # Clean up, zip, and persist the generated datadirs. Record the generation
+        # time so that we can correctly set the system clock offset in tests that
+        # use these files.
+        tmpdir = self.options.tmpdir
+        sprout_cache_path = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'cache', 'sprout')
+        for i in range(4):
+            node_path = os.path.join(tmpdir, 'node' + str(i), 'regtest')
+            os.remove(os.path.join(node_path, 'debug.log'))
+            os.remove(os.path.join(node_path, 'db.log'))
+            os.remove(os.path.join(node_path, 'peers.dat'))
+            os.remove(os.path.join(node_path, 'fee_estimates.dat'))
+
+            wallet_tgz_path = os.path.join(sprout_cache_path, 'node' + str(i) + '_wallet.tar.gz')
+            if not os.path.isfile(wallet_tgz_path):
+                with tarfile.open(wallet_tgz_path, "w:gz") as tgz:
+                    tgz.add(os.path.join(node_path, 'wallet.dat'), arcname="")
+
+            os.remove(os.path.join(node_path, 'wallet.dat'))
+
+            if i == 0:
+                cache_config = {
+                    "cache_time": time.time()
+                }
+
+                with open(os.path.join(node_path, 'cache_config.json'), "w", encoding="utf8") as cache_conf_file:
+                    cache_conf_json = json.dumps(cache_config, indent=4)
+                    cache_conf_file.write(cache_conf_json)
+
+                cache_path = os.path.join(sprout_cache_path, 'chain_cache.tar.gz')
+                if not os.path.isfile(cache_path):
+                    with tarfile.open(cache_path, "w:gz") as tgz:
+                        tgz.add(node_path, arcname="")
+
+if __name__ == '__main__':
+    CreateSproutChainsTest().main()