Given following log snippets, their explanation, and nothing else, explain what failure, if any, occurred during build of this package.

  Snippets are in a format of [X] : [Y], where [X] is a log snippet, and [Y] is the explanation.

  Snippets are delimited with '================'.

  Drawing on information from all snippets, provide a concise explanation of the issue and recommend a solution.

  Explanation of the issue, and recommended solution, should take a handful of sentences.

  Snippets:

  [============================= test session starts ==============================
platform linux -- Python 3.13.0, pytest-8.3.4, pluggy-1.5.0
rootdir: /builddir/build/BUILD/mock-5.9-build/mock-git-3857.8f7301c
collected 37 items

tests/plugins/test_rpmautospec.py ............                           [ 32%]
tests/test_buildroot.py .                                                [ 35%]
tests/test_buildroot_lock.py .F.                                         [ 43%]
tests/test_config_loader.py .                                            [ 45%]
tests/test_config_templates.py ......x...                                [ 72%]
tests/test_installed_packages.py .                                       [ 75%]
tests/test_package_manager.py .........                                  [100%]]: [Test are included into the build process.]
=============
[FAILED tests/test_buildroot_lock.py::test_buildroot_lock_output - TypeError: ...
]: [Test named `test_buildroot_lock_output` has failed during the package build.]
=============
[    def test_buildroot_lock_output():
        """ test the buildroot_lock.json file format """
        tc, buildroot, plugins = _mock_vars(RPM_OUTPUT, REPOQUERY_OUTPUT)
&gt;       _call_method(plugins, buildroot)

tests/test_buildroot_lock.py:137: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
tests/test_buildroot_lock.py:105: in _call_method
    method()
py/mockbuild/plugins/buildroot_lock.py:115: in produce_lockfile
    fdlist.write(json.dumps(data, indent=4, sort_keys=True) + "\n")
/usr/lib64/python3.13/json/__init__.py:238: in dumps
    **kw).encode(obj)
/usr/lib64/python3.13/json/encoder.py:200: in encode
    chunks = self.iterencode(o, _one_shot=True)
/usr/lib64/python3.13/json/encoder.py:261: in iterencode
    return _iterencode(o, 0)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = &lt;json.encoder.JSONEncoder object at 0x7f2a44694a50&gt;
o = &lt;MagicMock name='mock.get_image_digest()' id='139819511716160'&gt;

    def default(self, o):
        """Implement this method in a subclass such that it returns
        a serializable object for ``o``, or calls the base implementation
        (to raise a ``TypeError``).
    
        For example, to support arbitrary iterators, you could
        implement default like this::
    
            def default(self, o):
                try:
                    iterable = iter(o)
                except TypeError:
                    pass
                else:
                    return list(iterable)
                # Let the base class default method raise the TypeError
                return super().default(o)
    
        """
&gt;       raise TypeError(f'Object of type {o.__class__.__name__} '
                        f'is not JSON serializable')
E       TypeError: Object of type MagicMock is not JSON serializable]: [The `test_buildroot_lock_output` test has failed with traceback `TypeError: Object of type MagicMock is not JSON serializable`

The `MagicMock` object is used for mocking the python object so this might be an issue in how the code is tested.]

Issue: One of the tests executed as part of the build has failed.
Resolution: Please fix the test or code tested by the test.