From 2ae866b59caab55afadb1531cc49705b0053c60e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ren=C3=A9=20Canna=C3=B2?= <rene.cannao@gmail.com>
Date: Sat, 21 Mar 2026 21:25:52 +0100
Subject: [PATCH] Add query_cache_unit-t to build and init Prometheus registry

- tests/unit/Makefile: Register query_cache_unit-t in the build system
- test_init.cpp: Create a real Prometheus registry in test_init_query_
  cache() since the Query_Cache constructor registers metrics via
  GloVars.prometheus_registry (nullptr would crash)
---
 test/tap/test_helpers/test_init.cpp | 7 +++++++
 test/tap/tests/unit/Makefile        | 7 ++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/test/tap/test_helpers/test_init.cpp b/test/tap/test_helpers/test_init.cpp
index d555ba1ca..3266df5c8 100644
--- a/test/tap/test_helpers/test_init.cpp
+++ b/test/tap/test_helpers/test_init.cpp
@@ -81,6 +81,13 @@ int test_init_query_cache() {
 		return 0;
 	}
 
+	// The Query_Cache constructor registers Prometheus metrics via
+	// GloVars.prometheus_registry. Provide a real registry so the
+	// constructor doesn't crash on nullptr dereference.
+	if (GloVars.prometheus_registry == nullptr) {
+		GloVars.prometheus_registry = std::make_shared<prometheus::Registry>();
+	}
+
 	GloMyQC = new MySQL_Query_Cache();
 	GloPgQC = new PgSQL_Query_Cache();
 
diff --git a/test/tap/tests/unit/Makefile b/test/tap/tests/unit/Makefile
index 3b52fcd12..c56e4e2b6 100644
--- a/test/tap/tests/unit/Makefile
+++ b/test/tap/tests/unit/Makefile
@@ -231,7 +231,7 @@ $(ODIR)/test_init.o: $(TEST_HELPERS_DIR)/test_init.cpp | $(ODIR)
 # Unit test targets
 # ===========================================================================
 
-UNIT_TESTS := smoke_test-t
+UNIT_TESTS := smoke_test-t query_cache_unit-t
 
 .PHONY: all
 all: $(UNIT_TESTS)
@@ -250,6 +250,11 @@ smoke_test-t: smoke_test-t.cpp $(TEST_HELPERS_OBJ) $(LIBPROXYSQLAR)
 		$(LIBPROXYSQLAR_FULL) $(STATIC_LIBS) $(MYLIBS) \
 		$(ALLOW_MULTI_DEF) -o $@
 
+query_cache_unit-t: query_cache_unit-t.cpp $(TEST_HELPERS_OBJ) $(LIBPROXYSQLAR)
+	$(CXX) $< $(TEST_HELPERS_OBJ) $(IDIRS) $(LDIRS) $(OPT) \
+		$(LIBPROXYSQLAR_FULL) $(STATIC_LIBS) $(MYLIBS) \
+		$(ALLOW_MULTI_DEF) -o $@
+
 
 # ===========================================================================
 # Clean