test: Show debug log on unit test failure

src/test/main.cpp

@@ -2,6 +2,21 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+/**
+ * See https://www.boost.org/doc/libs/1_71_0/libs/test/doc/html/boost_test/utf_reference/link_references/link_boost_test_module_macro.html
+ */
 #define BOOST_TEST_MODULE Bitcoin Core Test Suite
 
 #include <boost/test/unit_test.hpp>
+
+#include <test/util/setup_common.h>
+
+/** Redirect debug log to boost log */
+const std::function<void(const std::string&)> G_TEST_LOG_FUN = [](const std::string& s) {
+    if (s.back() == '\n') {
+        // boost will insert the new line
+        BOOST_TEST_MESSAGE(s.substr(0, s.size() - 1));
+    } else {
+        BOOST_TEST_MESSAGE(s);
+    }
+};