tests: More work on error handling

tests/fcntl/create.c

@@ -9,6 +9,10 @@ int main(void) {
     ERROR_IF(creat, fd, == -1);
     UNEXP_IF(creat, fd, < 0);
 
-    write(fd, "Hello World!\n", 13);
-    close(fd);
+    int written = write(fd, "Hello World!\n", 13);
+    ERROR_IF(write, written, == -1);
+
+    int c = close(fd);
+    ERROR_IF(close, c, == -1);
+    UNEXP_IF(close, c, != 0);
 }

tests/fcntl/fcntl.c

@@ -21,6 +21,11 @@ int main(void) {
 
     printf("fd %d duped into fd %d\n", newfd, newfd2);
 
-    close(newfd);
-    close(newfd2);
+    int c1 = close(newfd);
+    ERROR_IF(close, c1, == -1);
+    UNEXP_IF(close, c1, != 0);
+
+    int c2 = close(newfd2);
+    ERROR_IF(close, c2, == -1);
+    UNEXP_IF(close, c2, != 0);
 }