diff --git a/test/tap/tests/unit/Makefile b/test/tap/tests/unit/Makefile
new file mode 100644
index 000000000..5e3d0dde2
--- /dev/null
+++ b/test/tap/tests/unit/Makefile
@@ -0,0 +1,263 @@
+#!/bin/make -f
+#
+# Makefile for ProxySQL unit tests.
+#
+# Unit tests link against libproxysql.a with stub globals (test_globals.o)
+# instead of main.o, allowing individual components to be tested in
+# isolation without a running ProxySQL daemon or backend servers.
+#
+# See: GitHub issue #5473 (Phase 2.1: Test Infrastructure Foundation)
+
+
+PROXYSQL_PATH := $(shell while [ ! -f ./src/proxysql_global.cpp ]; do cd ..; done; pwd)
+
+include $(PROXYSQL_PATH)/include/makefiles_vars.mk
+include $(PROXYSQL_PATH)/include/makefiles_paths.mk
+
+
+# ===========================================================================
+# Include directories — mirrors test/tap/tests/Makefile
+# ===========================================================================
+
+IDIRS :=	-I$(TAP_IDIR) \
+			-I$(RE2_IDIR) \
+			-I$(PROXYSQL_IDIR) \
+			-I$(JEMALLOC_IDIR) \
+			-I$(LIBCONFIG_IDIR) \
+			-I$(MARIADB_IDIR) \
+			-I$(LIBDAEMON_IDIR) \
+			-I$(MICROHTTPD_IDIR) \
+			-I$(LIBHTTPSERVER_IDIR) \
+			-I$(CURL_IDIR) -I$(EV_IDIR) \
+			-I$(PROMETHEUS_IDIR) \
+			-I$(DOTENV_DYN_IDIR) \
+			-I$(SQLITE3_IDIR) \
+			-I$(JSON_IDIR) \
+			-I$(POSTGRESQL_IDIR) \
+			-I$(LIBSCRAM_IDIR) \
+			-I$(LIBUSUAL_IDIR) \
+			-I$(SSL_IDIR) \
+			-I$(ZSTD_IDIR) \
+			-I$(PROXYSQL_PATH)/include \
+			-I$(PROXYSQL_PATH)/test/tap/test_helpers
+
+
+# ===========================================================================
+# Library directories
+# ===========================================================================
+
+LDIRS :=	-L$(TAP_LDIR) \
+			-L$(RE2_LDIR) \
+			-L$(PROXYSQL_LDIR) \
+			-L$(JEMALLOC_LDIR) \
+			-L$(LIBCONFIG_LDIR) \
+			-L$(MARIADB_LDIR) \
+			-L$(LIBDAEMON_LDIR) \
+			-L$(MICROHTTPD_LDIR) \
+			-L$(LIBHTTPSERVER_LDIR) \
+			-L$(CURL_LDIR) -L$(EV_LDIR) \
+			-L$(PROMETHEUS_LDIR) \
+			-L$(DOTENV_DYN_LDIR) \
+			-L$(PCRE_LDIR) \
+			-L$(LIBINJECTION_LDIR) \
+			-L$(POSTGRESQL_LDIR) \
+			-L$(LIBSCRAM_LDIR) \
+			-L$(LIBUSUAL_LDIR) \
+			-L$(SSL_LDIR)
+
+ifeq ($(UNAME_S),Linux)
+	LDIRS += -L$(COREDUMPER_LDIR)
+endif
+ifeq ($(UNAME_S),Darwin)
+	IDIRS += -I/usr/local/include -I/opt/homebrew/include
+	LDIRS += -L/usr/local/lib -L/opt/homebrew/lib
+endif
+
+
+# ===========================================================================
+# ClickHouse include/link paths (enabled by default)
+# ===========================================================================
+
+CLICKHOUSE_CPP_PATH := $(DEPS_PATH)/clickhouse-cpp/clickhouse-cpp
+CLICKHOUSE_CPP_IDIR := $(CLICKHOUSE_CPP_PATH) -I$(CLICKHOUSE_CPP_PATH)/contrib/absl
+CLICKHOUSE_CPP_LDIR := $(CLICKHOUSE_CPP_PATH)/clickhouse
+LZ4_LDIR := $(DEPS_PATH)/lz4/lz4/lib
+
+IDIRS += -I$(CLICKHOUSE_CPP_IDIR)
+
+
+# ===========================================================================
+# libproxysql.a — the core library under test
+# ===========================================================================
+
+LIBPROXYSQLAR := $(PROXYSQL_LDIR)/libproxysql.a
+
+
+# ===========================================================================
+# Static libraries required at link time
+# ===========================================================================
+
+STATIC_LIBS := $(CITYHASH_LDIR)/libcityhash.a \
+			   $(LZ4_LDIR)/liblz4.a \
+			   $(ZSTD_LDIR)/libzstd.a
+
+ifeq ($(PROXYSQLCLICKHOUSE),1)
+	STATIC_LIBS += $(CLICKHOUSE_CPP_LDIR)/libclickhouse-cpp-lib.a
+endif
+
+ifeq ($(UNAME_S),Linux)
+	STATIC_LIBS += $(COREDUMPER_LDIR)/libcoredumper.a
+endif
+
+ifeq ($(PROXYSQLGENAI),1)
+	STATIC_LIBS += $(SQLITE3_LDIR)/../libsqlite_rembed.a $(SQLITE3_LDIR)/vec.o
+endif
+
+
+# ===========================================================================
+# Linker flags — platform-specific
+# ===========================================================================
+
+ifeq ($(UNAME_S),Darwin)
+# macOS: No -Bstatic/-Bdynamic; use explicit .a paths for static linking.
+# libproxysql.a already bundles most deps on Darwin (see src/Makefile).
+LIBPROXYSQLAR_FULL := $(LIBPROXYSQLAR) \
+	$(JEMALLOC_LDIR)/libjemalloc.a \
+	$(MICROHTTPD_LDIR)/libmicrohttpd.a \
+	$(LIBHTTPSERVER_LDIR)/libhttpserver.a \
+	$(PCRE_LDIR)/libpcre.a \
+	$(PCRE_LDIR)/libpcrecpp.a \
+	$(LIBDAEMON_LDIR)/libdaemon.a \
+	$(LIBCONFIG_LDIR)/libconfig++.a \
+	$(LIBCONFIG_LDIR)/libconfig.a \
+	$(CURL_LDIR)/libcurl.a \
+	$(SQLITE3_LDIR)/sqlite3.o \
+	$(LIBINJECTION_LDIR)/libinjection.a \
+	$(EV_LDIR)/libev.a \
+	$(LIBSCRAM_LDIR)/libscram.a \
+	$(LIBUSUAL_LDIR)/libusual.a \
+	$(MARIADB_LDIR)/libmariadbclient.a \
+	$(RE2_LDIR)/libre2.a \
+	$(POSTGRESQL_PATH)/interfaces/libpq/libpq.a \
+	$(POSTGRESQL_PATH)/common/libpgcommon.a \
+	$(POSTGRESQL_PATH)/port/libpgport.a
+
+MYLIBS := -lssl -lcrypto -lpthread -lm -lz \
+		  -liconv -lgnutls -lprometheus-cpp-pull -lprometheus-cpp-core -luuid \
+		  -lzstd $(LWGCOV)
+else
+# Linux/FreeBSD: Use -Bstatic/-Bdynamic for controlled linking.
+LIBPROXYSQLAR_FULL := $(LIBPROXYSQLAR)
+
+MYLIBS := -Wl,--export-dynamic -Wl,-Bdynamic -lgnutls -lcurl -lssl -lcrypto -luuid \
+		  -Wl,-Bstatic -lconfig -lproxysql -ldaemon -lconfig++ -lre2 -lpcrecpp -lpcre \
+		  -lmariadbclient -lhttpserver -lmicrohttpd -linjection -lev \
+		  -lprometheus-cpp-pull -lprometheus-cpp-core \
+		  -Wl,-Bstatic -lpq -lpgcommon -lpgport \
+		  -Wl,-Bdynamic -lpthread -lm -lz -lzstd -lrt -ldl \
+		  -lscram -lusual -Wl,--allow-multiple-definition \
+		  $(LWGCOV)
+endif
+
+ifneq ($(NOJEMALLOC),1)
+ifeq ($(UNAME_S),Linux)
+	MYLIBS += -Wl,-Bstatic -ljemalloc -Wl,-Bdynamic
+endif
+endif
+
+
+# ===========================================================================
+# Compiler flags
+# ===========================================================================
+
+PSQLCH :=
+ifeq ($(PROXYSQLCLICKHOUSE),1)
+	PSQLCH := -DPROXYSQLCLICKHOUSE
+endif
+PSQLGA :=
+ifeq ($(PROXYSQLGENAI),1)
+	PSQLGA := -DPROXYSQLGENAI
+endif
+PSQL31 :=
+ifeq ($(PROXYSQL31),1)
+	PSQL31 := -DPROXYSQL31
+endif
+PSQLFFTO :=
+ifeq ($(PROXYSQLFFTO),1)
+	PSQLFFTO := -DPROXYSQLFFTO
+endif
+PSQLTSDB :=
+ifeq ($(PROXYSQLTSDB),1)
+	PSQLTSDB := -DPROXYSQLTSDB
+endif
+
+OPT := $(STDCPP) -O0 -ggdb $(PSQLCH) $(PSQLGA) $(PSQL31) $(PSQLFFTO) $(PSQLTSDB) \
+	   -DGITVERSION=\"$(GIT_VERSION)\" $(NOJEM) $(WGCOV) $(WASAN) \
+	   -Wl,--no-as-needed -Wl,-rpath,$(TAP_LDIR)
+
+ifeq ($(UNAME_S),Darwin)
+	OPT := $(STDCPP) -O0 -ggdb $(PSQLCH) $(PSQLGA) $(PSQL31) $(PSQLFFTO) $(PSQLTSDB) \
+		   -DGITVERSION=\"$(GIT_VERSION)\" $(NOJEM) $(WGCOV) $(WASAN)
+endif
+
+
+# ===========================================================================
+# Test helper objects
+# ===========================================================================
+
+TEST_HELPERS_DIR := $(PROXYSQL_PATH)/test/tap/test_helpers
+ODIR := obj
+
+TEST_HELPERS_OBJ := $(ODIR)/test_globals.o $(ODIR)/test_init.o $(ODIR)/tap.o
+
+$(ODIR):
+	mkdir -p $(ODIR)
+
+# Compile tap.o directly from tap.cpp to avoid the full TAP build chain
+# and its cpp-dotenv dependency (which doesn't build on macOS).
+# Unit tests only need the core TAP functions: plan(), ok(), is(), etc.
+TAP_SRC := $(TAP_PATH)/tap.cpp
+$(ODIR)/tap.o: $(TAP_SRC) | $(ODIR)
+	$(CXX) -c -o $@ $< $(OPT) $(IDIRS) -w
+
+$(ODIR)/test_globals.o: $(TEST_HELPERS_DIR)/test_globals.cpp | $(ODIR)
+	$(CXX) -c -o $@ $< $(OPT) $(IDIRS) -Wall
+
+$(ODIR)/test_init.o: $(TEST_HELPERS_DIR)/test_init.cpp | $(ODIR)
+	$(CXX) -c -o $@ $< $(OPT) $(IDIRS) -Wall
+
+
+# ===========================================================================
+# Unit test targets
+# ===========================================================================
+
+UNIT_TESTS := smoke_test-t
+
+.DEFAULT: default
+.PHONY: default debug all
+
+default: all
+debug: OPT += -DDEBUG
+debug: all
+
+all: $(UNIT_TESTS)
+
+ALLOW_MULTI_DEF :=
+ifneq ($(UNAME_S),Darwin)
+	ALLOW_MULTI_DEF := -Wl,--allow-multiple-definition
+endif
+
+smoke_test-t: smoke_test-t.cpp $(TEST_HELPERS_OBJ) $(LIBPROXYSQLAR)
+	$(CXX) $< $(TEST_HELPERS_OBJ) $(IDIRS) $(LDIRS) $(OPT) \
+		$(LIBPROXYSQLAR_FULL) $(STATIC_LIBS) $(MYLIBS) \
+		$(ALLOW_MULTI_DEF) -o $@
+
+
+# ===========================================================================
+# Clean
+# ===========================================================================
+
+.PHONY: clean
+.SILENT: clean
+clean:
+	rm -rf $(ODIR) $(UNIT_TESTS)
diff --git a/test/tap/tests/unit/smoke_test-t.cpp b/test/tap/tests/unit/smoke_test-t.cpp
new file mode 100644
index 000000000..5982b8c9d
--- /dev/null
+++ b/test/tap/tests/unit/smoke_test-t.cpp
@@ -0,0 +1,111 @@
+/**
+ * @file smoke_test-t.cpp
+ * @brief Smoke test for the ProxySQL unit test harness.
+ *
+ * Validates that the test infrastructure (test_globals + test_init)
+ * works correctly by performing minimal operations on each supported
+ * component. This test must pass before any component-specific unit
+ * tests can be trusted.
+ *
+ * Test coverage:
+ *   1. test_init_minimal() — GloVars is usable
+ *   2. test_init_auth()    — MySQL_Authentication add/lookup cycle
+ *   3. test_cleanup_*()    — clean shutdown without leaks
+ *
+ * @see Phase 2.1 of the Unit Testing Framework (GitHub issue #5473)
+ */
+
+#include "tap.h"
+#include "test_globals.h"
+#include "test_init.h"
+
+#include "proxysql.h"
+#include "MySQL_Authentication.hpp"
+#include "PgSQL_Authentication.h"
+
+// Extern declarations for Glo* pointers (defined in test_globals.cpp)
+extern MySQL_Authentication *GloMyAuth;
+extern PgSQL_Authentication *GloPgAuth;
+
+/**
+ * @brief Test that minimal initialization sets up GloVars correctly.
+ */
+static void test_minimal_init() {
+	int rc = test_init_minimal();
+	ok(rc == 0, "test_init_minimal() returns 0");
+	ok(GloVars.datadir != nullptr, "GloVars.datadir is set after init");
+	ok(GloVars.global.nostart == true, "GloVars.global.nostart is true");
+}
+
+/**
+ * @brief Test MySQL_Authentication add/lookup/del cycle.
+ */
+static void test_mysql_auth_basic() {
+	int rc = test_init_auth();
+	ok(rc == 0, "test_init_auth() returns 0");
+	ok(GloMyAuth != nullptr, "GloMyAuth is initialized");
+	ok(GloPgAuth != nullptr, "GloPgAuth is initialized");
+
+	// Add a frontend user
+	bool added = GloMyAuth->add(
+		(char *)"testuser",          // username
+		(char *)"testpass",          // password
+		USERNAME_FRONTEND,           // user type
+		false,                       // use_ssl
+		0,                           // default_hostgroup
+		(char *)"",                  // default_schema
+		false,                       // schema_locked
+		false,                       // transaction_persistent
+		false,                       // fast_forward
+		100,                         // max_connections
+		(char *)"",                  // attributes
+		(char *)""                   // comment
+	);
+	ok(added == true, "GloMyAuth->add() succeeds for frontend user");
+
+	// Verify user exists
+	bool exists = GloMyAuth->exists((char *)"testuser");
+	ok(exists == true, "GloMyAuth->exists() returns true for added user");
+
+	// Verify user does not exist
+	bool not_exists = GloMyAuth->exists((char *)"nonexistent");
+	ok(not_exists == false, "GloMyAuth->exists() returns false for unknown user");
+
+	// Cleanup
+	test_cleanup_auth();
+	ok(GloMyAuth == nullptr, "GloMyAuth is nullptr after cleanup");
+	ok(GloPgAuth == nullptr, "GloPgAuth is nullptr after cleanup");
+}
+
+/**
+ * @brief Test idempotency of init/cleanup functions.
+ */
+static void test_idempotency() {
+	// Double init should be safe
+	int rc1 = test_init_minimal();
+	int rc2 = test_init_minimal();
+	ok(rc1 == 0 && rc2 == 0, "test_init_minimal() is idempotent");
+
+	int rc3 = test_init_auth();
+	int rc4 = test_init_auth();
+	ok(rc3 == 0 && rc4 == 0, "test_init_auth() is idempotent");
+
+	// Double cleanup should be safe
+	test_cleanup_auth();
+	test_cleanup_auth();  // should not crash
+	ok(1, "test_cleanup_auth() double-call does not crash");
+
+	test_cleanup_minimal();
+	test_cleanup_minimal();  // should not crash
+	ok(1, "test_cleanup_minimal() double-call does not crash");
+}
+
+int main() {
+	plan(15);
+
+	test_minimal_init();
+	test_mysql_auth_basic();
+	test_idempotency();
+
+	return exit_status();
+}