ansible - testing constructed inventory plugin

ansible.cfg

[inventory]
enable_plugins = ini, constructed

dynamic.config

plugin: constructed
strict: False
keyed_groups:
  - prefix: foo
    key: foo|default('none')

hosts

host1
host2 foo=bar
host3 foo=foo
host4
host5 foo=foo

output

ansible host5 -i hosts -i dynamic.config -m debug -a 'var=groups'
host5 | SUCCESS => {
    "changed": false,
    "groups": {
        "all": [
            "host1",
            "host2",
            "host3",
            "host4",
            "host5"
        ],
        "foo_bar": [
            "host2"
        ],
        "foo_foo": [
            "host5",
            "host3"
        ],
        "foo_none": [
            "host4",
            "host1"
        ],
        "ungrouped": [
            "host1",
            "host2",
            "host3",
            "host4",
            "host5"
        ]
    }
}