diff-example.sh

#!/usr/bin/env bash

# Copyright 2017 The Cockroach Authors.
#
# Use of this software is governed by the CockroachDB Software License
# included in the /LICENSE file.


# Diff a failed Go example [0] against its expected output.
#
# By default, when an example fails, Go prints "got:", followed by the
# actual output, then prints "want:", followed by the expected output. When the
# output grows beyond several lines, as it often does, it's virtually impossible
# to visually parse where the output differs, especially when whitespace is
# involved. This script parses the output and prints it as a unified diff to
# make the difference obvious.
#
# If this script produces no output, it means the actual and expected output
# matched.
#
# Sample usage:
#
# $ make test PKG=./pkg/cli TESTS=Example_zone | scripts/diff-example.sh
#
# [0]: https://golang.org/pkg/testing/#hdr-Examples

set -euo pipefail

do_diff() {
if [ -x"$(command -v colordiff)" ];then
 colordiff "$@"
else
 diff "$@"
fi
}

cd$(mktemp -d)
trap'rm -rf $PWD' EXIT

cat >in

# The actual output is everything after "got:" but before "want:".
<in sed -n "
 /^got:$/,/^want:$/{
 //d
 p
}">got

# The desired output is everything after "want:", excluding the status about
# whether the test passed or failed.
<in sed "1,/^want:$/d"| grep -Ev "^(PASS|FAIL)">want

do_diff -u want got