Option --color=always does not work on tests

[carlomilanesi]

Problem

The option --color=always should keep ANSI codes when output is sent to a pipe.
Instead, when running a test, the green texts ok, and the red texts FAILED are not colored.

Steps

Create a project using cargo new dummy --lib.
Type cargo --color=always test | more.
The text ok appears three times not colored, instead of dark green.

Possible Solution(s)

No response

Notes

Test output is directed to stdout, while normal cargo output goes to stderr. It appears that ANSI codes are kept only for stderr.

Version

cargo 1.66.1 (ad779e08b 2023-01-10)
release: 1.66.1
commit-hash: ad779e08be893e57a9e17a810223a3e966f8c0d8
commit-date: 2023-01-10
host: x86_64-unknown-linux-gnu
libgit2: 1.5.0 (sys:0.16.0 vendored)
libcurl: 7.83.1-DEV (sys:0.4.55+curl-7.83.1 vendored ssl:OpenSSL/1.1.1q)
os: Linux Mint 20.3 (una) [64-bit]

[ehuss]

Thanks for the report! The issue is that the tests are handled by a separate process with its own CLI and environment variables. To force color for the tests, too, you need to pass the color option to the test harness as in:

cargo test --color=always -- --color=always

Closing as a duplicate of #1983