Add regression test for parse zero operands at eof

tests/input/regression/test_no_operands_eof.asm

@@ -0,0 +1,5 @@
+; regression test for two issues:
+;  - parsing two zero operand instructions in a row
+;  - a zero operand instruction just before eof
+    syscall
+    ret

tests/regression.c

@@ -23,9 +23,46 @@ MunitResult test_regression_trivia_head(const MunitParameter params[], void *dat
 
     ast_node_free(result.node);
     tokenlist_free(list);
+    return MUNIT_OK;
+}
+
+MunitResult test_no_operands_eof(const MunitParameter params[], void *data) {
+    (void)params;
+    (void)data;
+
+    lexer_t *lex = &(lexer_t){};
+    error_t *err = lexer_open(lex, "tests/input/regression/test_no_operands_eof.asm");
+    munit_assert_null(err);
+
+    tokenlist_t *list;
+    err = tokenlist_alloc(&list);
+    munit_assert_null(err);
+
+    err = tokenlist_fill(list, lex);
+    munit_assert_null(err);
+
+    parse_result_t result = parse(list->head);
+    munit_assert_null(result.err);
+    munit_assert_null(result.next);
+
+    // Both children should be instructions
+    munit_assert_size(result.node->len, ==, 2);
+    munit_assert_int(result.node->children[0]->id, ==, NODE_INSTRUCTION);
+    munit_assert_int(result.node->children[1]->id, ==, NODE_INSTRUCTION);
+
+    // And they should have empty operands
+    munit_assert_size(result.node->children[0]->len, ==, 2);
+    munit_assert_size(result.node->children[1]->len, ==, 2);
+    munit_assert_size(result.node->children[0]->children[1]->len, ==, 0);
+    munit_assert_size(result.node->children[1]->children[1]->len, ==, 0);
+
+    ast_node_free(result.node);
+    tokenlist_free(list);
+    return MUNIT_OK;
 }
 
 MunitTest regression_tests[] = {
     {"/trivia_head",     test_regression_trivia_head, nullptr, nullptr, MUNIT_TEST_OPTION_NONE, nullptr},
+    {"/no_operands_eof", test_no_operands_eof,        nullptr, nullptr, MUNIT_TEST_OPTION_NONE, nullptr},
     {nullptr,            nullptr,                     nullptr, nullptr, MUNIT_TEST_OPTION_NONE, nullptr}
 };