filter-impossible-oackages-only-required.test

--TEST--
When filtering packages from the pool that cannot meet the fixed/locked requirements, ensure that the requirements for a package that is not required anywhere is not used to filter, as it will be ultimately be removed.

--REQUEST--
{
    "require": {
        "first/pkg": "*",
        "root/req": "*"
    },
    "locked": [
        {"name": "first/pkg", "version": "1.0.0", "require": {"second/pkg": "*"}},
        {"name": "second/pkg", "version": "1.0.0", "require": {"third/pkg": "1.0.0"}},
        {"name": "third/pkg", "version": "1.0.0", "require": {"fourth/pkg": "1.0.0"}},
        {"name": "fourth/pkg", "version": "1.0.0"}
    ],
    "allowList": [
        "root/req"
    ],
    "allowTransitiveDeps": true
}

--FIXED--
[
]

--PACKAGE-REPOS--
[
    [
        {"name": "first/pkg", "version": "1.0.0", "require": {"second/pkg": "*"}},
        {"name": "second/pkg", "version": "1.0.0", "require": {"third/pkg": "1.0.0"}},
        {"name": "second/pkg", "version": "2.0.0"},
        {"name": "third/pkg", "version": "1.0.0", "require": {"fourth/pkg": "1.0.0"}},
        {"name": "third/pkg", "version": "2.0.0", "require": {"fourth/pkg": "2.0.0"}},
        {"name": "fourth/pkg", "version": "1.0.0"},
        {"name": "fourth/pkg", "version": "2.0.0"},
        {"name": "root/req", "version": "1.0.0", "require": {"second/pkg": "2.0.0"}, "require": {"fourth/pkg": "2.0.0"}}
    ]
]

--EXPECT--
[
    "first/pkg-1.0.0.0 (locked)",
    "second/pkg-1.0.0.0 (locked)",
    "third/pkg-1.0.0.0 (locked)",
    "root/req-1.0.0.0",
    "fourth/pkg-1.0.0.0",
    "fourth/pkg-2.0.0.0"
]