well, nothing works, at least there is something to debug

test/test_parser.c

@@ -1,5 +1,58 @@
-#include <stdlib.h>
+#include "lexer.h"
+#include "parser.h"
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <setjmp.h>
+#include <cmocka.h>
 
-int main() {
-    return EXIT_SUCCESS;
+static void test_parsing_basic_expression(void **state) {
+    (void) state;
+
+    char expr[256] = "2 + 3 / 66 * 789";
+    ASTNodeArray tokens;
+    ASTNode node;
+    
+    assert_int_equal(tokenize(expr, &tokens), LEXER_OK);
+    assert_int_equal(tokens.len, 7);
+
+    ASTNodeArray_get(&tokens, 0, &node);
+    assert_int_equal(node.type, NODE_INTEGER);
+    assert_int_equal(node.data.integer, 2);
+
+    ASTNodeArray_get(&tokens, 1, &node);
+    assert_int_equal(node.type, NODE_BINARY_OP);
+    assert_int_equal(node.data.binary.op, OP_ADD);
+
+    ASTNodeArray_get(&tokens, 2, &node);
+    assert_int_equal(node.type, NODE_INTEGER);
+    assert_int_equal(node.data.integer, 3);
+
+    ASTNodeArray_get(&tokens, 3, &node);
+    assert_int_equal(node.type, NODE_BINARY_OP);
+    assert_int_equal(node.data.binary.op, OP_DIV);
+
+    ASTNodeArray_get(&tokens, 4, &node);
+    assert_int_equal(node.type, NODE_INTEGER);
+    assert_int_equal(node.data.integer, 66);
+
+    ASTNodeArray_get(&tokens, 5, &node);
+    assert_int_equal(node.type, NODE_BINARY_OP);
+    assert_int_equal(node.data.binary.op, OP_MUL);
+
+    ASTNodeArray_get(&tokens, 6, &node);
+    assert_int_equal(node.type, NODE_INTEGER);
+    assert_int_equal(node.data.integer, 789);
+
+    AST tree = parse(&tokens);
+    assert_int_equal(tree.head->type, NODE_BINARY_OP);
+}
+
+int main(void) {
+    const struct CMUnitTest tests [] = {
+        cmocka_unit_test(test_parsing_basic_expression),
+    };
+
+    return cmocka_run_group_tests(tests, NULL, NULL);
 }