Timer fixes & tests added

tests/tactility-core/mutex_test.cpp

@@ -0,0 +1,34 @@
+#include "doctest.h"
+#include "tactility_core.h"
+#include "mutex.h"
+
+static int thread_with_mutex_parameter(void* parameter) {
+    Mutex mutex = (Mutex)parameter;
+    tt_mutex_acquire(mutex, TtWaitForever);
+    return 0;
+}
+
+TEST_CASE("a mutex can block a thread") {
+    Mutex mutex = tt_mutex_alloc(MutexTypeNormal);
+    tt_mutex_acquire(mutex, TtWaitForever);
+
+    Thread* thread = tt_thread_alloc_ex(
+        "thread",
+        1024,
+        &thread_with_mutex_parameter,
+        mutex
+    );
+    tt_thread_start(thread);
+
+    tt_delay_ms(5);
+    CHECK_EQ(tt_thread_get_state(thread), ThreadStateRunning);
+
+    tt_mutex_release(mutex);
+
+    tt_delay_ms(5);
+    CHECK_EQ(tt_thread_get_state(thread), ThreadStateStopped);
+
+    tt_thread_join(thread);
+    tt_thread_free(thread);
+    tt_mutex_free(mutex);
+}