fix(ai): release horn when human driver takes over from AI

tests/unit/main.cpp

@@ -0,0 +1,40 @@
+#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
+#include "stdafx.h"
+#include "doctest.h"
+
+#include "utilities/Globals.h"
+
+namespace {
+
+// the simulation draws random numbers (brake delays, pressures, wheel damage) from engines shared by
+// everything. reseeding them before every run of a test case, subcases included, gives each test the
+// same numbers whether it runs alone from the IDE or among all the others
+class deterministic_random : public doctest::IReporter {
+public:
+	explicit deterministic_random(doctest::ContextOptions const &) {}
+
+	void test_case_start(doctest::TestCaseData const &) override { reseed(); }
+	void test_case_reenter(doctest::TestCaseData const &) override { reseed(); }
+
+	// the rest of doctest's reporter interface: a listener reports nothing, the console reporter does that
+	void report_query(doctest::QueryData const &) override { /* nothing to report */ }
+	void test_run_start() override { /* nothing to report */ }
+	void test_run_end(doctest::TestRunStats const &) override { /* nothing to report */ }
+	void test_case_end(doctest::CurrentTestCaseStats const &) override { /* nothing to report */ }
+	void test_case_exception(doctest::TestCaseException const &) override { /* nothing to report */ }
+	void subcase_start(doctest::SubcaseSignature const &) override { /* nothing to report */ }
+	void subcase_end() override { /* nothing to report */ }
+	void log_assert(doctest::AssertData const &) override { /* nothing to report */ }
+	void log_message(doctest::MessageData const &) override { /* nothing to report */ }
+	void test_case_skipped(doctest::TestCaseData const &) override { /* nothing to report */ }
+
+private:
+	static void reseed() {
+		Global.random_engine.seed(1);
+		Global.local_random_engine.seed(1);
+	}
+};
+
+} // namespace
+
+DOCTEST_REGISTER_LISTENER("deterministic_random", 1, deterministic_random);