test: add integration plugin tests

[DmitriyLewen]

Description

See #7276

CI/CD test - https://github.com/aquasecurity/trivy/actions/runs/10214386342/job/28261673506?pr=7299#step:5:1044

Related issues

• Close test(plugin): add integration tests #7276

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[knqyf263]

The VM, module, and K8s tests take longer to run and require a special setup. That's why they are separated. I think the plugin test can be part of the normal integration tests.

[DmitriyLewen]

updated in 33cf9d5

[knqyf263]

What if passing io.Writer here?

trivy/integration/integration_test.go

Line 284 in 88ba460

app.SetOut(io.Discard)

[knqyf263]

I mean

func execute(osArgs []string, out io.Writer) error {
    if out == nil {
        out = io.Discard
    }
    ...
}

[DmitriyLewen]

I tried to use your idea.
But we use os.Stdout in plugin package.

I used NewManager instead of defaultManager in app.go to use Stdout from cobra.
It works, but there is problem with case when plugin is output.
We need to add output for plugin in Options:

trivy/pkg/flag/options.go

Lines 511 to 533 in 0c6687d

	func (o *Options) outputPluginWriter(ctx context.Context) (io.Writer, func() error, error) {
	pluginName := strings.TrimPrefix(o.Output, "plugin=")
	pr, pw := io.Pipe()
	wait, err := plugin.Start(ctx, pluginName, plugin.Options{
	Args: o.OutputPluginArgs,
	Stdin: pr,
	})
	if err != nil {
	return nil, nil, xerrors.Errorf("plugin start: %w", err)
	}
	cleanup := func() error {
	if err = pw.Close(); err != nil {
	return xerrors.Errorf("failed to close pipe: %w", err)
	}
	if err = wait(); err != nil {
	return xerrors.Errorf("plugin error: %w", err)
	}
	return nil
	}
	return pw, cleanup, nil
	}

i am not sure that we need to do that now.
I would leave this workaround until the tests become more numerous and complex, which would require these changes.

But if you want to do it - tell me and I will continue the research

[knqyf263]

OK, we can improve it later.

[knqyf263]

OK, we can improve it later.