FUCK YEAH, it works, it was the is_valid thing fo slices that was inverted, did the test by brute force and damn, is the expected AST

test/test_parser.c

@@ -46,7 +46,56 @@ static void test_parsing_basic_expression(void **state) {
     assert_int_equal(node.data.integer, 789);
 
     AST tree = parse(&tokens);
+    // Assert head is +
     assert_int_equal(tree.head->type, NODE_BINARY_OP);
+    assert_int_equal(tree.head->data.binary.op, OP_ADD);
+
+    assert_int_equal(tree.head->data.binary.left->type, NODE_INTEGER);
+    assert_int_equal(tree.head->data.binary.left->data.integer, 2);
+
+
+    assert_int_equal(
+            tree.head->data.binary.right->type,
+            NODE_BINARY_OP
+            );
+    assert_int_equal(
+            tree.head->data.binary.right->data.binary.op, 
+            OP_MUL
+            );
+
+    assert_int_equal(
+            tree.head->data.binary.right->data.binary.right->type,
+            NODE_INTEGER);
+    assert_int_equal(
+            tree.head->data.binary.right->data.binary.right->data.integer,
+            789);
+
+    assert_int_equal(
+            tree.head->data.binary.right->data.binary.left->type, 
+            NODE_BINARY_OP
+            );
+    assert_int_equal(
+            tree.head->data.binary.right->data.binary.left->data.binary.op, 
+            OP_DIV
+            );
+
+    assert_int_equal(
+            tree.head->data.binary.right->data.binary.left->data.binary.right->type, 
+            NODE_INTEGER
+            );
+    assert_int_equal(
+            tree.head->data.binary.right->data.binary.left->data.binary.right->data.integer, 
+            66
+            );
+
+    assert_int_equal(
+            tree.head->data.binary.right->data.binary.left->data.binary.left->type, 
+            NODE_INTEGER
+            );
+    assert_int_equal(
+            tree.head->data.binary.right->data.binary.left->data.binary.left->data.integer, 
+            3
+            );
 }
 
 int main(void) {