Add rudimentary test

.gitignore

@@ -1,5 +1,4 @@
 obj/
-test/
 *.o
 *.a
 *.so

test/CMakeLists.txt

@@ -0,0 +1,4 @@
+
+add_executable(arena_allocator_test test_arena.c ../src/arena.c)
+
+target_include_directories(arena_allocator_test PUBLIC ../include)

test/test_arena.c

@@ -0,0 +1,53 @@
+
+#include "arena.h"
+#include <stdlib.h> // exit(), EXIT_FAILURE
+#include <string.h> // memset
+#include <stdio.h>  // fprintf
+#include <unistd.h> // sysconf
+
+int main()
+{
+
+    printf(".");
+
+    arena_t a = arena_new();
+    if (arena_new_failed(&a)) {
+        fprintf(stderr, "\narena_new failed");
+        exit(EXIT_FAILURE);
+    }
+
+    size_t size = sysconf(_SC_PAGE_SIZE);
+    if (size == -1) {
+        perror("sysconf");
+        exit(EXIT_FAILURE);
+    }
+
+    // test many small allocations
+    for (int i = 0; i < size * 8; i++) {
+        char* s = arena_alloc(&a, 4 * sizeof *s);
+        if (!s) {
+            fprintf(stderr, "\narena_alloc failed");
+            exit(EXIT_FAILURE);
+        }
+        memset(s, 'a', 4);
+    }
+
+    // test a few allocations above the cap*2
+    for (int i = 0; i < 2; i++) {
+        size_t n = a.cap * 3 + 123;
+        printf("allocating %d bytes\n", n);
+        volatile char* s = arena_alloc(&a, n);
+        if (!s) {
+            fprintf(stderr, "\narena_alloc failed");
+            exit(EXIT_FAILURE);
+        }
+    }
+
+    int ok = arena_delete(&a);
+    if (ok == -1) {
+        fprintf(stderr, "arena_delete failed");
+        exit(EXIT_FAILURE);
+    }
+    
+    return EXIT_SUCCESS;
+}