From 0c5015d4677faf8f2f983e5f8445c59bca60f3e1 Mon Sep 17 00:00:00 2001
From: Mahmoud Al-Qudsi <mqudsi@neosmart.net>
Date: Thu, 28 Mar 2019 18:23:32 -0500
Subject: [PATCH] Correct the reversed diff output for all tests

This has been driving nuts for years. The output of the diff emitted
when a test fails was always reversed, because the diff tool is called
with `${difftool} ${new} ${old}` so all the `-` and `+` contexts are
reversed, and the highlights are all screwed up.

The output of a `make test` run should show what has changed from the
baseline/expected, not how the expected differs from the actual. When
considered from both the perspective of intentional changes to the test
outputs and failed test outputs, it is desirable to see how the test
output has changed from the previously expected, and not the other way
around.

(If you were used to the previous behavior, I apologize. But it was
wrong.)
---
 tests/interactive.fish | 4 ++--
 tests/invocation.sh    | 8 ++++----
 tests/test.fish        | 4 ++--
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/tests/interactive.fish b/tests/interactive.fish
index 933749446..f6a05a12b 100644
--- a/tests/interactive.fish
+++ b/tests/interactive.fish
@@ -69,11 +69,11 @@ function test_file
         say red "fail"
         if test $out_status -ne 0
             say yellow "Output differs for file $file. Diff follows:"
-            colordiff -u $file.tmp.out $file.out
+            colordiff -u $file.out $file.tmp.out
         end
         if test $err_status -ne 0
             say yellow "Error output differs for file $file. Diff follows:"
-            colordiff -u $file.tmp.err $file.err
+            colordiff -u $file.err $file.tmp.err
         end
         if test $exit_status -ne 0
             say yellow "Exit status differs for file $file."
diff --git a/tests/invocation.sh b/tests/invocation.sh
index 8ced43e4e..728636ca4 100755
--- a/tests/invocation.sh
+++ b/tests/invocation.sh
@@ -245,10 +245,10 @@ test_file() (
     mv -f "${test_stderr}.new" "${test_stderr}"
 
     # Check the results
-    if ! diff "${test_stdout}" "${want_stdout}" >/dev/null 2>/dev/null ; then
+    if ! diff "${want_stdout}" "${test_stdout}" >/dev/null 2>/dev/null ; then
         out_status=1
     fi
-    if ! diff "${test_stderr}" "${want_stderr}" >/dev/null 2>/dev/null ; then
+    if ! diff "${want_stderr}" "${test_stderr}" >/dev/null 2>/dev/null ; then
         err_status=1
     fi
 
@@ -264,11 +264,11 @@ test_file() (
 
         if [ "$out_status" != '0' ] ; then
             say "$term_yellow" "Output differs for file $file. Diff follows:"
-            "$difftool" -u "${test_stdout}" "${want_stdout}"
+            "$difftool" -u "${want_stdout}" "${test_stdout}"
         fi
         if [ "$err_status" != '0' ] ; then
             say "$term_yellow" "Error output differs for file $file. Diff follows:"
-            "$difftool" -u "${test_stderr}" "${want_stderr}"
+            "$difftool" -u  "${want_stderr}" "${test_stderr}"
         fi
         rc=1
     fi
diff --git a/tests/test.fish b/tests/test.fish
index 0711e0933..62025fe0d 100644
--- a/tests/test.fish
+++ b/tests/test.fish
@@ -55,11 +55,11 @@ function test_file
         say red "fail"
         if test $out_status -ne 0
             say yellow "Output differs for file $file. Diff follows:"
-            colordiff -u $base.tmp.out $base.out
+            colordiff -u $base.out $base.tmp.out
         end
         if test $err_status -ne 0
             say yellow "Error output differs for file $file. Diff follows:"
-            colordiff -u $base.tmp.err $base.err
+            colordiff -u $base.err $base.tmp.err
         end
         if test $exit_status -ne 0
             say yellow "Exit status differs for file $file."