Add test suite for `RandomNumberGenerator`

tests/test_main.cpp

@@ -56,6 +56,7 @@
 #include "test_pck_packer.h"
 #include "test_physics_2d.h"
 #include "test_physics_3d.h"
+#include "test_random_number_generator.h"
 #include "test_rect2.h"
 #include "test_render.h"
 #include "test_shader_lang.h"

tests/test_random_number_generator.h

@@ -0,0 +1,111 @@
+/*************************************************************************/
+/*  test_random_number_generator.h                                       */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef TEST_RANDOM_NUMBER_GENERATOR_H
+#define TEST_RANDOM_NUMBER_GENERATOR_H
+
+#include "core/math/random_number_generator.h"
+#include "tests/test_macros.h"
+
+namespace TestRandomNumberGenerator {
+
+TEST_CASE("[RandomNumberGenerator] Zero for first number immediately after seeding") {
+	Ref<RandomNumberGenerator> rng = memnew(RandomNumberGenerator);
+	rng->set_seed(0);
+	uint32_t n1 = rng->randi();
+	uint32_t n2 = rng->randi();
+	INFO("Initial random values: " << n1 << " " << n2);
+	CHECK(n1 != 0);
+
+	rng->set_seed(1);
+	uint32_t n3 = rng->randi();
+	uint32_t n4 = rng->randi();
+	INFO("Values after changing the seed: " << n3 << " " << n4);
+	CHECK(n3 != 0);
+}
+
+TEST_CASE("[RandomNumberGenerator] Restore state") {
+	Ref<RandomNumberGenerator> rng = memnew(RandomNumberGenerator);
+	rng->randomize();
+	uint64_t last_seed = rng->get_seed();
+	INFO("Current seed: " << last_seed);
+
+	rng->randi();
+	rng->randi();
+
+	CHECK_MESSAGE(rng->get_seed() == last_seed,
+			"The seed should remain the same after generating some numbers");
+
+	uint64_t saved_state = rng->get_state();
+	INFO("Current state: " << saved_state);
+
+	real_t f1_before = rng->randf();
+	real_t f2_before = rng->randf();
+	INFO("This seed produces: " << f1_before << " " << f2_before);
+
+	// Restore now.
+	rng->set_state(saved_state);
+
+	real_t f1_after = rng->randf();
+	real_t f2_after = rng->randf();
+	INFO("Resetting the state produces: " << f1_after << " " << f2_after);
+
+	String msg = "Should restore the sequence of numbers after resetting the state";
+	CHECK_MESSAGE(f1_before == f1_after, msg);
+	CHECK_MESSAGE(f2_before == f2_after, msg);
+}
+
+TEST_CASE("[RandomNumberGenerator] Restore from seed") {
+	Ref<RandomNumberGenerator> rng = memnew(RandomNumberGenerator);
+	rng->set_seed(0);
+	INFO("Current seed: " << rng->get_seed());
+	uint32_t s0_1_before = rng->randi();
+	uint32_t s0_2_before = rng->randi();
+	INFO("This seed produces: " << s0_1_before << " " << s0_2_before);
+
+	rng->set_seed(9000);
+	INFO("Current seed: " << rng->get_seed());
+	uint32_t s9000_1 = rng->randi();
+	uint32_t s9000_2 = rng->randi();
+	INFO("This seed produces: " << s9000_1 << " " << s9000_2);
+
+	rng->set_seed(0);
+	INFO("Current seed: " << rng->get_seed());
+	uint32_t s0_1_after = rng->randi();
+	uint32_t s0_2_after = rng->randi();
+	INFO("This seed produces: " << s0_1_after << " " << s0_2_after);
+
+	String msg = "Should restore the sequence of numbers after resetting the seed";
+	CHECK_MESSAGE(s0_1_before == s0_1_after, msg);
+	CHECK_MESSAGE(s0_2_before == s0_2_after, msg);
+}
+} // namespace TestRandomNumberGenerator
+
+#endif // TEST_RANDOM_NUMBER_GENERATOR_H