Need unit test for `swift package init --type macro`

[grynspan]

Description

SwiftPM is missing unit test coverage for the swift package init --type macro subcommand/option.

Expected behavior

There should be a unit test.

Actual behavior

There is not a unit test.

Steps to reproduce

N/A

Swift Package Manager version/commit hash

1ff8e993f179857a3dee8aa7d5ff10a4a581b990

Swift & OS version (output of swift --version ; uname -a)

N/A