From fc5c829532a9a275fe51959b1d0158622ee69ae6 Mon Sep 17 00:00:00 2001
From: Ivan Trubach <mr.trubach@icloud.com>
Date: Thu, 18 Jul 2024 17:01:35 +0300
Subject: [PATCH] testers.testEqualContents: use diffoscope instead of diffing
 find output

Before this change, testers.testEqualContents implementation had several
bugs (e.g. executables at different paths were not considered equal). So
we switch to diffoscope that that is designed to handle exactly these
kinds of comparisons and gives more insights into the differences in the
output.
---
 pkgs/build-support/testers/default.nix | 27 ++++++++------------------
 1 file changed, 8 insertions(+), 19 deletions(-)

diff --git a/pkgs/build-support/testers/default.nix b/pkgs/build-support/testers/default.nix
index 516ab90db503..20d2957134c3 100644
--- a/pkgs/build-support/testers/default.nix
+++ b/pkgs/build-support/testers/default.nix
@@ -1,4 +1,4 @@
-{ pkgs, pkgsLinux, buildPackages, lib, callPackage, runCommand, stdenv, substituteAll, testers }:
+{ pkgs, pkgsLinux, buildPackages, diffoscopeMinimal, lib, callPackage, runCommand, stdenv, substituteAll, testers }:
 # Documentation is in doc/build-helpers/testers.chapter.md
 {
   # See https://nixos.org/manual/nixpkgs/unstable/#tester-lycheeLinkCheck
@@ -27,33 +27,22 @@
     expected,
   }: runCommand "equal-contents-${lib.strings.toLower assertion}" {
     inherit assertion actual expected;
+    nativeBuildInputs = [ diffoscopeMinimal ];
   } ''
     echo "Checking:"
-    echo "$assertion"
-    if ! diff -U5 -r "$actual" "$expected" --color=always
+    printf '%s\n' "$assertion"
+    if ! diffoscope --no-progress --text-color=always --exclude-directory-metadata=no -- "$actual" "$expected"
     then
       echo
       echo 'Contents must be equal, but were not!'
       echo
       echo "+: expected,   at $expected"
       echo "-: unexpected, at $actual"
-      exit 1
+      false
     else
-      find "$expected" -type f -executable > expected-executables | sort
-      find "$actual" -type f -executable > actual-executables | sort
-      if ! diff -U0 actual-executables expected-executables --color=always
-      then
-        echo
-        echo "Contents must be equal, but some files' executable bits don't match"
-        echo
-        echo "+: make this file executable in the actual contents"
-        echo "-: make this file non-executable in the actual contents"
-        exit 1
-      else
-        echo "expected $expected and actual $actual match."
-        echo 'OK'
-        touch $out
-      fi
+      echo "expected $expected and actual $actual match."
+      echo OK
+      touch -- "$out"
     fi
   '';