Tests for random seeding

test/CMakeLists.txt

@@ -1,12 +1,20 @@
 find_package(Threads REQUIRED)
 enable_testing()
 
+# Usage: add_test(NAME src1.c src2.c ...
+#                [EXTRA_LIBS lib1 lib2]
+#                [EXTRA_INCLUDES dir1 dir2]
+#                [ENV "VAR=val;VAR2=val2"])
 function(add_test TEST_NAME)
-	message("Adding test: ${TEST_NAME} -> ${ARGN}")
-	add_executable(${TEST_NAME} ${ARGN})
-	target_include_directories(${TEST_NAME} PRIVATE ${INCLUDE_DIRS})
-	target_link_libraries(${TEST_NAME} ${CMOCKA_LIBRARY} ${SDL_LIBRARY})
+	cmake_parse_arguments(ARG "" "" "EXTRA_LIBS;EXTRA_INCLUDES;ENV" ${ARGN})
+	message("Adding test: ${TEST_NAME} -> ${ARG_UNPARSED_ARGUMENTS}")
+	add_executable(${TEST_NAME} ${ARG_UNPARSED_ARGUMENTS})
+	target_include_directories(${TEST_NAME} PRIVATE ${INCLUDE_DIRS} ${ARG_EXTRA_INCLUDES})
+	target_link_libraries(${TEST_NAME} ${CMOCKA_LIBRARY} ${SDL_LIBRARY} ${ARG_EXTRA_LIBS})
 	_add_test(${TEST_NAME} ${TEST_NAME})
+	if(ARG_ENV)
+		set_tests_properties(${TEST_NAME} PROPERTIES ENVIRONMENT "${ARG_ENV}")
+	endif()
 endfunction()
 
 add_test(test_util test_util.c ../src/util.c)
@@ -17,10 +25,15 @@ add_test(test_input test_input.c ../src/input.c ../src/keyboard.c)
 add_test(test_position test_position.c ../src/position.c)
 add_test(test_collisions test_collisions.c ../src/collisions.c)
 
+add_test(test_random test_random.c ../src/random.c ../src/util.c
+	EXTRA_INCLUDES ${CMAKE_SOURCE_DIR}/lib/bh_random/src
+	EXTRA_LIBS bh_random
+)
+
 # roommatrix needs a real SDL renderer (lightmap texture), so it uses the
 # offscreen video driver. Extra libs: SDL_image + SDL_ttf (pulled in by
 # texture.c) and physfs (pulled in by io_util.c / physfsrwops.c).
-add_executable(test_roommatrix
+add_test(test_roommatrix
 	test_roommatrix.c
 	../src/roommatrix.c
 	../src/texture.c
@@ -29,16 +42,6 @@ add_executable(test_roommatrix
 	../src/position.c
 	../src/io_util.c
 	../src/physfsrwops.c
-)
-target_include_directories(test_roommatrix PRIVATE ${INCLUDE_DIRS})
-target_link_libraries(test_roommatrix
-	${CMOCKA_LIBRARY}
-	${SDL_LIBRARY}
-	${SDL_IMAGE_LIBRARY}
-	${SDL_TTF_LIBRARY}
-	${PHYSFS_LIBRARY}
-)
-_add_test(test_roommatrix test_roommatrix)
-set_tests_properties(test_roommatrix PROPERTIES
-	ENVIRONMENT "SDL_VIDEODRIVER=offscreen;SDL_RENDER_DRIVER=software"
-)
+	EXTRA_LIBS ${SDL_IMAGE_LIBRARY} ${SDL_TTF_LIBRARY} ${PHYSFS_LIBRARY}
+	ENV "SDL_VIDEODRIVER=offscreen;SDL_RENDER_DRIVER=software"
+)

test/test_random.c

@@ -0,0 +1,128 @@
+/*
+ * BreakHack - A dungeone crawler RPG
+ * Copyright (C) 2026  Linus Probert <linus.probert@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "cmocka_include.h"
+#include "../src/random.h"
+
+/* set_random_seed / get_random_seed round-trip */
+static void
+test_seed_roundtrip(void **state)
+{
+	(void)state;
+
+	set_random_seed(42);
+	assert_int_equal(get_random_seed(), 42);
+
+	set_random_seed(0xDEADBEEF);
+	assert_int_equal(get_random_seed(), 0xDEADBEEF);
+}
+
+/* Same seed must produce identical map seeds for all 20 levels */
+static void
+test_map_seeds_are_deterministic(void **state)
+{
+	(void)state;
+
+	unsigned int first[20], second[20];
+
+	set_random_seed(12345);
+	for (int i = 0; i < 20; ++i)
+		first[i] = get_random_map_seed(i + 1);
+
+	set_random_seed(12345);
+	for (int i = 0; i < 20; ++i)
+		second[i] = get_random_map_seed(i + 1);
+
+	for (int i = 0; i < 20; ++i)
+		assert_int_equal(first[i], second[i]);
+}
+
+/* Two different seeds must not produce the same map seed sequence */
+static void
+test_different_seeds_differ(void **state)
+{
+	(void)state;
+
+	unsigned int a[20], b[20];
+
+	set_random_seed(11111);
+	for (int i = 0; i < 20; ++i)
+		a[i] = get_random_map_seed(i + 1);
+
+	set_random_seed(22222);
+	for (int i = 0; i < 20; ++i)
+		b[i] = get_random_map_seed(i + 1);
+
+	/* At least one level must differ — all matching would be a collision */
+	int any_differ = 0;
+	for (int i = 0; i < 20; ++i) {
+		if (a[i] != b[i]) {
+			any_differ = 1;
+			break;
+		}
+	}
+	assert_true(any_differ);
+}
+
+/* get_random(max) must always return a value in [0, max] */
+static void
+test_get_random_bounds(void **state)
+{
+	(void)state;
+
+	set_random_seed(99999);
+
+	for (unsigned int max = 0; max <= 100; ++max) {
+		for (int trial = 0; trial < 50; ++trial) {
+			unsigned int r = get_random(max);
+			assert_true(r <= max);
+		}
+	}
+}
+
+/*
+ * Seed 0 is the "uninitialised" sentinel in init_seed().
+ * set_random_seed(0) works fine, but get_random_seed() will subsequently
+ * re-init with time(NULL) because init_seed() sees seed==0 as unset.
+ * Verify that the code doesn't crash and that get_random_seed returns
+ * something non-zero after that lazy re-init.
+ */
+static void
+test_seed_zero_reinit(void **state)
+{
+	(void)state;
+
+	set_random_seed(0);
+	/* get_random_seed() triggers init_seed() which replaces 0 with time(NULL) */
+	assert_int_not_equal(get_random_seed(), 0);
+	/* map seeds are now populated from the time-based seed — must not crash */
+	(void)get_random_map_seed(1);
+	(void)get_random_map_seed(20);
+}
+
+int
+main(void)
+{
+	const struct CMUnitTest tests[] = {
+	    cmocka_unit_test(test_seed_roundtrip),         cmocka_unit_test(test_map_seeds_are_deterministic),
+	    cmocka_unit_test(test_different_seeds_differ), cmocka_unit_test(test_get_random_bounds),
+	    cmocka_unit_test(test_seed_zero_reinit),
+	};
+
+	return cmocka_run_group_tests(tests, NULL, NULL);
+}

test/test_roommatrix.c

@@ -1,6 +1,6 @@
 /*
  * BreakHack - A dungeone crawler RPG
- * Copyright (C) 2025  Linus Probert <linus.probert@gmail.com>
+ * Copyright (C) 2026  Linus Probert <linus.probert@gmail.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -15,7 +15,6 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-
 #include <SDL3/SDL.h>
 #include "cmocka_include.h"
 #include "../src/roommatrix.h"
@@ -141,4 +140,4 @@ main(void)
 	};
 
 	return cmocka_run_group_tests(tests, NULL, NULL);
-}
+}