Add arena test

build.bat

@@ -13,6 +13,12 @@ set RELEASE_LINE=%RELEASE% %WRN% %COMMON% -link -incremental:no %LINK_RELEASE%
 
 mkdir build
 cd build
+
+cl.exe  -Fe:test_arena.exe ../test/test_arena.cpp %DEBUG_LINE%
+if %errorlevel% neq 0 exit /b %errorlevel%
+test_arena.exe
+if %errorlevel% neq 0 exit /b %errorlevel%
+
 cl.exe  -Fe:cpp_debug.exe ../test/main.cpp %DEBUG_LINE%
 if %errorlevel% neq 0 exit /b %errorlevel%
 cl.exe  -Fe:cpp_release.exe ../test/main.cpp %RELEASE_LINE%

io.c

@@ -1,4 +1,5 @@
 #include "io.h"
+#include <stdarg.h>
 
 #ifndef IO_SNPRINTF
     #include <stdio.h>

test/test_arena.cpp

@@ -0,0 +1,14 @@
+#include "../io.c"
+
+#define MA_ASSERT(x) IO_Assert(x)
+#include "../arena.c"
+
+int main() {
+    MA_Scratch scratch;
+    int *thing = MA_PushStruct(scratch, int);
+    *thing = 10;
+
+    MA_Arena *arena = MA_Bootstrap();
+    float *thingf = MA_PushStruct(arena, float);
+    *thingf = 10.0f;
+}