From 58a94ea5626520fa3883ae7df1ff21347796e2c9 Mon Sep 17 00:00:00 2001
From: Joonas Koivunen <joonas.koivunen@gmail.com>
Date: Thu, 24 Aug 2017 18:17:35 +0300
Subject: [PATCH] CONTRIBUTING: add manual testing section

---
 CONTRIBUTING.md | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 7da1182ca672..ef95a50dcef9 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -73,6 +73,19 @@ Of course there's little sense in writing the output yourself or copying it arou
 Therefore you can simply run `tests/ui/update-all-references.sh` and check whether
 the output looks as you expect with `git diff`. Commit all `*.stderr` files, too.
 
+### Testing manually
+
+Manually testing against an example file is useful if you have added some
+`println!`s and test suite output becomes unreadable.  To try clippy with your
+local modifications, run `cargo run -- -L ./target/debug input.rs` from the
+working copy root. Your test file, here `input.rs`, needs to have clippy
+enabled as a plugin:
+
+```rust
+#![feature(plugin)]
+#![plugin(clippy)]
+```
+
 ## Contributions
 
 Clippy welcomes contributions from everyone.