From 0957e26c88958618933e37ec587cc495231875ad Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Tue, 19 Aug 2025 16:59:04 +0300
Subject: [PATCH] tests: allow for `VAUTOFIX=1
 ./vlib/v/slow_tests/repl/repl_test.v`, describe repl_test.v in TESTS.md

---
 TESTS.md                               | 15 +++++++++++++++
 vlib/v/slow_tests/repl/runner/runner.v |  7 +++++++
 2 files changed, 22 insertions(+)

diff --git a/TESTS.md b/TESTS.md
index 18ed3d58e9..6476adc18b 100644
--- a/TESTS.md
+++ b/TESTS.md
@@ -80,6 +80,21 @@ Each `.c.must_have` file, consists of multiple lines. Each of these
 lines, *should* be present *at least once* in the output, when the .vv
 file is compiled with `-o -` .
 
+## REPL tests
+
+The test runner for these is `vlib/v/slow_tests/repl/repl_test.v`.
+
+The test cases for the V REPL, are stored in .repl files, in the folder
+`vlib/v/slow_tests/repl/`. Each .repl file in this folder, contains several
+lines of input to the V repl, followed by a single line of `===output===`,
+and then the output lines, that the repl would normally show for the input
+lines.
+
+If you change the compiler or the REPL source, and you have breaks in those
+.repl files, you can replace the current output in them, by running several
+times `VAUTOFIX=1 ./vlib/v/slow_tests/repl/repl_test.v`, until all the
+files are fixed and the test pass.
+
 ## `v vlib/v/slow_tests/run_project_folders_test.v`
 
 This *test runner*, checks whether whole project folders, can be compiled, and run.
diff --git a/vlib/v/slow_tests/repl/runner/runner.v b/vlib/v/slow_tests/repl/runner/runner.v
index c85e63d7c0..c14bca1b62 100644
--- a/vlib/v/slow_tests/repl/runner/runner.v
+++ b/vlib/v/slow_tests/repl/runner/runner.v
@@ -3,6 +3,8 @@ module runner
 import os
 import v.util.diff
 
+const is_vautofix = os.getenv('VAUTOFIX') != ''
+
 pub struct RunnerOptions {
 pub:
 	wd    string
@@ -62,6 +64,11 @@ pub fn run_repl_file(wd string, vexec string, file string) !string {
 	}
 	os.rm(input_temporary_filename)!
 	if result != output {
+		if is_vautofix {
+			new_content := input + '===output===\n' + r.output.trim_right('\n\r') + '\n'
+			os.write_file(file, new_content)!
+			eprintln('>>> fixed file: `${file}`, new_content.len: ${new_content.len}')
+		}
 		return diff_error(file, output, result)
 	}
 	return file.replace('./', '')