Many transactions unit test

This is a network unit test which keeps increasing the number of
transactions sent to be externalized. This is to test the gossiping and
consensus protocol implementation works with large numbers of
transactions.

source/agora/test/ManyTransactions.d

@@ -0,0 +1,51 @@
+/*******************************************************************************
+
+    Each block send double the txs
+
+    Run via:
+    $ dtest=agora.test.ManyTransactions dub test
+
+    Copyright:
+        Copyright (c) 2019-2021 BOSAGORA Foundation
+        All rights reserved.
+
+    License:
+        MIT License. See LICENSE for details.
+
+*******************************************************************************/
+
+module agora.test.ManyTransactions;
+
+version (unittest):
+
+import agora.test.Base;
+import agora.utils.Log;
+import agora.utils.PrettyPrinter;
+
+mixin AddLogger!();
+
+unittest
+{
+    TestConf conf;
+    conf.consensus.quorum_threshold = 100;
+    auto network = makeTestNetwork!TestAPIManager(conf);
+    network.start();
+    scope(exit) network.shutdown();
+    scope(failure) network.printLogs();
+    network.waitForDiscovery();
+
+    auto nodes = network.clients;
+    auto node_1 = nodes[0];
+
+    const txsInBlockTarget = 32;
+    ulong posted_txs = 8; // From Genesis
+    while (posted_txs  < txsInBlockTarget)
+    {
+        auto last_block = node_1.getBlock(node_1.getBlockHeight());
+        auto txs = last_block.spendable().map!(txb => txb.split(WK.Keys.byRange.take(2).map!(kp => kp.address)).sign());
+        txs.each!(tx => node_1.postTransaction(tx));
+        posted_txs = txs.walkLength;
+        log.info("Sent {} TXs", posted_txs);
+        network.expectHeight(Height(node_1.getBlockHeight() + 1), 10.seconds);
+    }
+}