Damn, it works, the lexer actually works, that's amazing, need to test the bad cases but at least i'm sure it can detect and process correct math expressions

test/test_lexer.c

@@ -6,6 +6,45 @@
 #include <setjmp.h>
 #include <cmocka.h>
 
+static void test_tokenize_normal_expresion(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, '+');
+
+    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, '/');
+
+    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, '*');
+
+    ASTNodeArray_get(&tokens, 6, &node);
+    assert_int_equal(node.type, NODE_INTEGER);
+    assert_int_equal(node.data.integer, 789);
+}
+
 static void test_string_to_number_normal(void **state) {
     (void) state;
 
@@ -36,6 +75,7 @@ int main(void) {
     const struct CMUnitTest tests[] = {
         cmocka_unit_test(test_string_to_number_normal),
         cmocka_unit_test(test_string_to_number_overflow),
+        cmocka_unit_test(test_tokenize_normal_expresion),
     };
 
     return cmocka_run_group_tests(tests, NULL, NULL);