[init] Add new command line arg for use only in functional tests

some of the existing command line args are to be only used in
functional tests. ex: addrmantest, fastprune etc.. make a separate
category -test=<option> for these so that code is cleaner and
user's debug-help output is straightforward.

Author: stratospher

src/common/args.cpp

@@ -682,6 +682,17 @@ std::string HelpMessageOpt(const std::string &option, const std::string &message
            std::string("\n\n");
 }
 
+const std::vector<std::string> TEST_OPTIONS_DOC{
+};
+
+bool HasTestOption(const ArgsManager& args, const std::string& test_option)
+{
+    const auto options = args.GetArgs("-test");
+    return std::any_of(options.begin(), options.end(), [test_option](const auto& option) {
+        return option == test_option;
+    });
+}
+
 fs::path GetDefaultDataDir()
 {
     // Windows: C:\Users\Username\AppData\Roaming\Bitcoin

src/common/args.h

@@ -447,6 +447,11 @@ bool HelpRequested(const ArgsManager& args);
 /** Add help options to the args manager */
 void SetupHelpOptions(ArgsManager& args);
 
+extern const std::vector<std::string> TEST_OPTIONS_DOC;
+
+/** Checks if a particular test option is present in -test command-line arg options */
+bool HasTestOption(const ArgsManager& args, const std::string& test_option);
+
 /**
  * Format a string to be used as group of options in help messages
  *

src/init.cpp

@@ -611,6 +611,7 @@ void SetupServerArgs(ArgsManager& argsman)
     argsman.AddArg("-limitdescendantcount=<n>", strprintf("Do not accept transactions if any ancestor would have <n> or more in-mempool descendants (default: %u)", DEFAULT_DESCENDANT_LIMIT), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-limitdescendantsize=<n>", strprintf("Do not accept transactions if any ancestor would have more than <n> kilobytes of in-mempool descendants (default: %u).", DEFAULT_DESCENDANT_SIZE_LIMIT_KVB), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-addrmantest", "Allows to test address relay on localhost", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
+    argsman.AddArg("-test=<option>", "Pass a test-only option. Options include : " + Join(TEST_OPTIONS_DOC, ", ") + ".", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-capturemessages", "Capture all P2P messages to disk", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-mocktime=<n>", "Replace actual time with " + UNIX_EPOCH_TIME + " (default: 0)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-maxsigcachesize=<n>", strprintf("Limit sum of signature cache and script execution cache sizes to <n> MiB (default: %u)", DEFAULT_MAX_SIG_CACHE_BYTES >> 20), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
@@ -1024,6 +1025,22 @@ bool AppInitParameterInteraction(const ArgsManager& args)
     if (args.GetBoolArg("-peerbloomfilters", DEFAULT_PEERBLOOMFILTERS))
         nLocalServices = ServiceFlags(nLocalServices | NODE_BLOOM);
 
+    if (args.IsArgSet("-test")) {
+        if (chainparams.GetChainType() != ChainType::REGTEST) {
+            return InitError(Untranslated("-test=<option> should only be used in functional tests"));
+        }
+        const std::vector<std::string> options = args.GetArgs("-test");
+        for (const std::string& option : options) {
+            auto it = std::find_if(TEST_OPTIONS_DOC.begin(), TEST_OPTIONS_DOC.end(), [&option](const std::string& doc_option) {
+                size_t pos = doc_option.find(" (");
+                return (pos != std::string::npos) && (doc_option.substr(0, pos) == option);
+            });
+            if (it == TEST_OPTIONS_DOC.end()) {
+                InitWarning(strprintf(_("Unrecognised option \"%s\" provided in -test=<option>."), option));
+            }
+        }
+    }
+
     // Also report errors from parsing before daemonization
     {
         kernel::Notifications notifications{};