Add <datadir>/settings.json persistent settings storage.

Persistent settings are used in followup PRs #15936 to unify gui settings
between bitcoin-qt and bitcoind, and #15937 to add a load_on_startup flag to
the loadwallet RPC and maintain a dynamic list of wallets that should be loaded
on startup that also can be shared between bitcoind and bitcoin-qt.

1 files changed, 23 insertions, 0 deletions

diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index 257328974b..cc2a5fcdbd 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -9,6 +9,7 @@
 #include <key.h>  // For CKey
 #include <optional.h>
 #include <sync.h>
+#include <test/util/logging.h>
 #include <test/util/setup_common.h>
 #include <test/util/str.h>
 #include <uint256.h>
@@ -1128,6 +1129,28 @@ BOOST_FIXTURE_TEST_CASE(util_ChainMerge, ChainMergeTestingSetup)
     BOOST_CHECK_EQUAL(out_sha_hex, "f0b3a3c29869edc765d579c928f7f1690a71fbb673b49ccf39cbc4de18156a0d");
 }
 
+BOOST_AUTO_TEST_CASE(util_ReadWriteSettings)
+{
+    // Test writing setting.
+    TestArgsManager args1;
+    args1.LockSettings([&](util::Settings& settings) { settings.rw_settings["name"] = "value"; });
+    args1.WriteSettingsFile();
+
+    // Test reading setting.
+    TestArgsManager args2;
+    args2.ReadSettingsFile();
+    args2.LockSettings([&](util::Settings& settings) { BOOST_CHECK_EQUAL(settings.rw_settings["name"].get_str(), "value"); });
+
+    // Test error logging, and remove previously written setting.
+    {
+        ASSERT_DEBUG_LOG("Failed renaming settings file");
+        fs::remove(GetDataDir() / "settings.json");
+        fs::create_directory(GetDataDir() / "settings.json");
+        args2.WriteSettingsFile();
+        fs::remove(GetDataDir() / "settings.json");
+    }
+}
+
 BOOST_AUTO_TEST_CASE(util_FormatMoney)
 {
     BOOST_CHECK_EQUAL(FormatMoney(0), "0.00");