tree 9a0e5cb7e8523e5f5884c16ecbc1a07a947f1518
parent 7f7c0c9a3b63b6b052714bbd1848b1b0723f6389
author Matt Stark <msta@google.com> 1776745313 +1000
committer gn-scoped@luci-project-accounts.iam.gserviceaccount.com <gn-scoped@luci-project-accounts.iam.gserviceaccount.com> 1776815446 -0700

Add diffs to EXPECT_EQ.

Previously, the user would have to manually write:
EXPECT_EQ(a, b) << "Want:\n" << b << "\nGot:\n" << a;

The vast majority of the time this got shortened to on of:
// Where does one end and the other begin? Which one is which?
// How do you detect a single-word or single-character diff?
EXPECT_EQ(a, b) << b << "\n" << a;
// It just prints "failure" and nothing else.
EXPECT_EQ(a, b);

Which made it almost impossible to understand error mesasges GN output
for both humans and AI.

This change uses git to pretty-print a diff for test failures (with
color!), falling back to a simple Want:\n...\nGot:\n... format

Change-Id: Icc77e607fcba1bce1e76b60ffb4746a56a6a6964
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/21960
Commit-Queue: Matt Stark <msta@google.com>
Reviewed-by: Takuto Ikuta <tikuta@google.com>