diff --git a/makina-compiler/test/xyz/colinholzman/makina/ExternalTransitionTest.kt b/makina-compiler/test/xyz/colinholzman/makina/ExternalTransitionTest.kt
index 9218f8a..d626bd5 100644
--- a/makina-compiler/test/xyz/colinholzman/makina/ExternalTransitionTest.kt
+++ b/makina-compiler/test/xyz/colinholzman/makina/ExternalTransitionTest.kt
@@ -4,6 +4,7 @@ import org.junit.jupiter.api.Assertions
 import org.junit.jupiter.api.Test
 import java.io.File
 import java.util.concurrent.TimeUnit
+import kotlin.test.assertEquals
 
 class ExternalTransitionTest {
 
@@ -33,14 +34,14 @@ class ExternalTransitionTest {
                 .directory(File("./../test/external_transition"))
                 .command("make", "clean").start()
         makeClean.waitFor(10, TimeUnit.SECONDS)
+        assertEquals(false, makeClean.isAlive)
+        assertEquals(0, makeClean.exitValue())
 
         val make = ProcessBuilder()
                 .directory(File("./../test/external_transition"))
                 .command("make").start()
         make.waitFor(10, TimeUnit.SECONDS)
-
-        File("./../test/external_transition/out/test_output.txt").reader().use {
-            Assertions.assertEquals(output, it.readLines())
-        }
+        assertEquals(false, make.isAlive)
+        assertEquals(0, make.exitValue())
     }
 }
\ No newline at end of file
diff --git a/test/external_transition/test_driver.c b/test/external_transition/test_driver.c
index 36415c1..da48e18 100644
--- a/test/external_transition/test_driver.c
+++ b/test/external_transition/test_driver.c
@@ -1,12 +1,44 @@
 
 #include <stdio.h>
+#include <assert.h>
+#include <string.h>
 #include "out/test.h"
 
-FILE *output;
+static const char *expected_output[] = {
+    "s1_entry",
+    "s1_s2_entry",
+    "s1_s2_e1_guard",
+    "s1_s2_exit",
+    "s1_exit",
+    "s1_entry",
+    "s1_s2_entry",
+    "s1_s2_e1_guard",
+    "s1_s2_exit",
+    "s1_exit",
+    "s1_entry",
+    "s1_s2_entry",
+    "s1_s2_e2_guard",
+    "s1_s2_exit",
+    "s1_s2_entry",
+    "s1_s2_e2_guard",
+    "s1_s2_exit",
+    "s1_s2_entry"
+};
+
+#define N_EVENTS (sizeof(expected_output) / sizeof(const char *))
+
+static const char *actual_output[N_EVENTS];
+
+static size_t output_index = 0;
+
+#define PUSH_EVENT(e) do {              \
+    assert(output_index < N_EVENTS);    \
+    actual_output[output_index++] = e;  \
+} while (0)
 
 int s1_s2_entry(struct test *self, struct test_event *event) {
     (void)self; (void)event;
-    fprintf(output, "s1_s2_entry\n");
+    PUSH_EVENT("s1_s2_entry");
     return 0;
 }
 
@@ -14,51 +46,52 @@ static int guard = 0;
 
 int s1_s2_e1_guard(struct test *self, struct test_event *event) {
     (void)self; (void)event;
-    fprintf(output, "s1_s2_e1_guard\n");
+    PUSH_EVENT("s1_s2_e1_guard");
     return guard;
 }
 
 int s1_s2_e2_guard(struct test *self, struct test_event *event) {
     (void)self; (void)event;
-    fprintf(output, "s1_s2_e2_guard\n");
+    PUSH_EVENT("s1_s2_e2_guard");
     return guard;
 }
 
 int s1_s2_e1_action(struct test *self, struct test_event *event) {
     (void)self; (void)event;
-    fprintf(output, "s1_s2_e1_action\n");
+    PUSH_EVENT("s1_s2_e1_action");
     return 0;
 }
 
 int s1_s2_exit(struct test *self, struct test_event *event) {
     (void)self; (void)event;
-    fprintf(output, "s1_s2_exit\n");
+    PUSH_EVENT("s1_s2_exit");
     return 0;
 }
 
 int s1_entry(struct test *self, struct test_event *event) {
     (void)self; (void)event;
-    fprintf(output, "s1_entry\n");
+    PUSH_EVENT("s1_entry");
     return 0;
 }
 
 int s1_exit(struct test *self, struct test_event *event) {
     (void)self; (void)event;
-    fprintf(output, "s1_exit\n");
+    PUSH_EVENT("s1_exit");
     return 0;
 }
 
 int main (void) {
-    output = fopen("out/test_output.txt", "w+");
     struct test instance;
-    test_init(&instance);                                                       /*s1_entry, s1_s2_entry*/
-    test_process_event(&instance, &(struct test_event){.id = test_event_e1});   /*s1_s2_e1_guard, s1_s2_exit, s1_exit, s1_entry, s1_s2_entry*/
+    test_init(&instance);
+    test_process_event(&instance, &(struct test_event){.id = test_event_e1});
     guard = 1;
-    test_process_event(&instance, &(struct test_event){.id = test_event_e1});   /*s1_s2_e1_guard, s1_s2_exit, s1_exit, s1_entry, s1_s2_entry*/
+    test_process_event(&instance, &(struct test_event){.id = test_event_e1});
     guard = 0;
-    test_process_event(&instance, &(struct test_event){.id = test_event_e2});   /*s1_s2_e2_guard, s1_s2_exit, s1_s2_entry*/
+    test_process_event(&instance, &(struct test_event){.id = test_event_e2});
     guard = 1;
-    test_process_event(&instance, &(struct test_event){.id = test_event_e2});   /*s1_s2_e2_guard, s1_s2_exit, s1_s2_entry*/
-    fclose(output);
+    test_process_event(&instance, &(struct test_event){.id = test_event_e2});
+    for (size_t i = 0; i < N_EVENTS; ++i) {
+        assert(strcmp(expected_output[i], actual_output[i]) == 0);
+    }
     return 0;
 }
\ No newline at end of file