Add swift package add-target-plugin command

[hi2gage]

Adds swift package add-target-plugin command for adding plugins to target from CLI

Motivation:

Featured requested in #8169

Allows users to add package plugins to targets via command line.

Forums Discussion

Modifications:

Add new add-target-plugin command which aligns with the existing add-target-dependency command

> swift package add-target-plugin --help
OVERVIEW: Add a new target plugin to the manifest

USAGE: swift package add-target-plugin <plugin-name> <target-name> [--package <package>]

ARGUMENTS:
  <plugin-name>           The name of the new plugin
  <target-name>           The name of the target to update

OPTIONS:
  --package <package>     The package in which the plugin resides
  --version               Show the version.
  -h, -help, --help       Show help information.

Result:

After running the following command:

swift package add-target-plugin OpenAPIGenerator myTarget --package swift-openapi-generator

The following addition will be made to the Package.swift manifest:

.target(
  name: "myTarget",
  plugins: [
    .plugin(name: "OpenAPIGenerator", package: "swift-openapi-generator")
  ]
)

[dschaefer2]

@swift-ci please test

[dschaefer2]

@swift-ci please test self hosted windows

[bkhouri]

@swift-ci please test windows

[hi2gage]

@bkhouri is windows (non self hosted) being flakey or is this somehow related to changes I made?

It looks like #8434 passed so maybe I need rebase in the new changes?

[hi2gage]

@dschaefer2 @bkhouri just want to bump this, I rebased the new changes.

[hi2gage]

@swift-ci please test self hosted windows

[bkhouri]

@swift-ci please test

[bkhouri]

@swift-ci test self hosted windows

[bkhouri]

@swift-ci test self hosted windows

[bkhouri]

Could I ask that we add a bit more automated tests?

[bkhouri]

praise: I really appreciate the automated tests to validate the behaviour we want. Could I trouble you to add a few more that would check different use cases and fault injections?

• Calling add-target-plugin on a non-existing package
• Calling add-target-plugin providing all four combination of a valid/invalid plugin name and target name.

[hi2gage]

Hi @bkhouri,
Thanks for the feedback! I've added two additional tests to cover this scenario:

Calling add-target-plugin on a non-existing package

Regarding your second request about validating the plugin and target names: the CLI currently just passes those strings through to the Package.swift manifest without performing validation, similar to how add-target-dependency behaves. Because of that, it's not currently possible to add meaningful tests that assert on the existence of the plugin or target.

That being said, I'm happy to discuss adding validation to some of these commands, but I believe it's outside the scope of this PR.

[bkhouri]

@swift-ci test

[bkhouri]

@swift-ci test self hosted windows

[bkhouri]

Though I don't see how, for some reason, the Windows Self hosted pipeline seems to hang with this change.

[bkhouri]

@swift-ci test

[bkhouri]

@swift-ci test self hosted windows

[bkhouri]

@swift-ci test windows

[hi2gage]

@bkhouri ok I think I figured it out. Messed up the naming of the files.

Let's try it again!

[bkhouri]

@swift-ci test

[bkhouri]

@swift-ci test self hosted windows

[bkhouri]

@swift-ci test windows

[hi2gage]

@bkhouri I think the Swift Test macOS Platform is borked across other PRs as well. But I just pushed the final 🤞 windows fix.

[bkhouri]

@swift-ci test

[bkhouri]

@swift-ci test self hosted windows

[bkhouri]

@swift-ci test

[plemarquand]

@hi2gage This looks like it might benefit from the same code as in #8534 to allow add-target-plugin to be idempotent when adding a target plugin that already exists.