test_ext_autosummary.py

"""
    test_autosummary
    ~~~~~~~~~~~~~~~~

    Test the autosummary extension.

    :copyright: Copyright 2007-2022 by the Sphinx team, see AUTHORS.
    :license: BSD, see LICENSE for details.
"""

import sys
from io import StringIO
from unittest.mock import Mock, patch

import pytest
from docutils import nodes

from sphinx import addnodes
from sphinx.ext.autosummary import (autosummary_table, autosummary_toc, extract_summary,
                                    import_by_name, mangle_signature)
from sphinx.ext.autosummary.generate import (AutosummaryEntry, generate_autosummary_content,
                                             generate_autosummary_docs)
from sphinx.ext.autosummary.generate import main as autogen_main
from sphinx.testing.util import assert_node, etree_parse
from sphinx.util.docutils import new_document
from sphinx.util.osutil import cd

html_warnfile = StringIO()


default_kw = {
    'testroot': 'autosummary',
    'confoverrides': {
        'extensions': ['sphinx.ext.autosummary'],
        'autosummary_generate': True,
        'autosummary_generate_overwrite': False,
        'source_suffix': '.rst'
    }
}


@pytest.fixture(scope='function', autouse=True)
def unload_target_module():
    sys.modules.pop('target', None)


def test_mangle_signature():
    TEST = """
    () :: ()
    (a, b, c, d, e) :: (a, b, c, d, e)
    (a, b, c=1, d=2, e=3) :: (a, b[, c, d, e])
    (a, b, aaa=1, bbb=1, ccc=1, eee=1, fff=1, ggg=1, hhh=1, iii=1, jjj=1)\
    :: (a, b[, aaa, bbb, ccc, ...])
    (a, b, c=(), d=<foo>) :: (a, b[, c, d])
    (a, b, c='foobar()', d=123) :: (a, b[, c, d])
    (a, b[, c]) :: (a, b[, c])
    (a, b[, cxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx]) :: (a, b[, ...)
    (a, b='c=d, e=f, g=h', c=3) :: (a[, b, c])
    (a, b="c=d, e=f, g=h", c=3) :: (a[, b, c])
    (a, b='c=d, \\'e=f,\\' g=h', c=3) :: (a[, b, c])
    (a, b='c=d, ', e='\\\\' g=h, c=3) :: (a[, b, e, c])
    (a, b={'c=d, ': 3, '\\\\': 3}) :: (a[, b])
    (a=1, b=2, c=3) :: ([a, b, c])
    (a=1, b=<SomeClass: a, b, c>, c=3) :: ([a, b, c])
    (a=1, b=T(a=1, b=2), c=3) :: ([a, b, c])
    (a: Tuple[int, str], b: int) -> str :: (a, b)
    """

    TEST = [[y.strip() for y in x.split("::")] for x in TEST.split("\n")
            if '::' in x]
    for inp, outp in TEST:
        res = mangle_signature(inp).strip().replace("\u00a0", " ")
        assert res == outp, ("'%s' -> '%s' != '%s'" % (inp, res, outp))


def test_extract_summary(capsys):
    settings = Mock(language_code='en',
                    id_prefix='',
                    auto_id_prefix='',
                    pep_reference=False,
                    rfc_reference=False)
    document = new_document('', settings)

    # normal case
    doc = ['',
           'This is a first sentence. And second one.',
           '',
           'Second block is here']
    assert extract_summary(doc, document) == 'This is a first sentence.'

    # inliner case
    doc = ['This sentence contains *emphasis text having dots.*,',
           'it does not break sentence.']
    assert extract_summary(doc, document) == ' '.join(doc)

    # abbreviations
    doc = ['Blabla, i.e. bla.']
    assert extract_summary(doc, document) == ' '.join(doc)

    doc = ['Blabla, et al. bla.']
    assert extract_summary(doc, document) == ' '.join(doc)

    # literal
    doc = ['blah blah::']
    assert extract_summary(doc, document) == 'blah blah.'

    # heading
    doc = ['blah blah',
           '=========']
    assert extract_summary(doc, document) == 'blah blah'

    doc = ['=========',
           'blah blah',
           '=========']
    assert extract_summary(doc, document) == 'blah blah'

    # hyperlink target
    doc = ['Do `this <https://www.sphinx-doc.org/>`_ and that. '
           'blah blah blah.']
    assert (extract_summary(doc, document) ==
            'Do `this <https://www.sphinx-doc.org/>`_ and that.')

    _, err = capsys.readouterr()
    assert err == ''


@pytest.mark.sphinx('dummy', **default_kw)
def test_get_items_summary(make_app, app_params):
    import sphinx.ext.autosummary
    import sphinx.ext.autosummary.generate
    args, kwargs = app_params
    app = make_app(*args, **kwargs)
    sphinx.ext.autosummary.generate.setup_documenters(app)
    # monkey-patch Autosummary.get_items so we can easily get access to it's
    # results..
    orig_get_items = sphinx.ext.autosummary.Autosummary.get_items

    autosummary_items = {}

    def new_get_items(self, names, *args, **kwargs):
        results = orig_get_items(self, names, *args, **kwargs)
        for name, result in zip(names, results):
            autosummary_items[name] = result
        return results

    def handler(app, what, name, obj, options, lines):
        assert isinstance(lines, list)

        # ensure no docstring is processed twice:
        assert 'THIS HAS BEEN HANDLED' not in lines
        lines.append('THIS HAS BEEN HANDLED')
    app.connect('autodoc-process-docstring', handler)

    sphinx.ext.autosummary.Autosummary.get_items = new_get_items
    try:
        app.builder.build_all()
    finally:
        sphinx.ext.autosummary.Autosummary.get_items = orig_get_items

    html_warnings = app._warning.getvalue()
    assert html_warnings == ''

    expected_values = {
        'withSentence': 'I have a sentence which spans multiple lines.',
        'noSentence': "this doesn't start with a capital.",
        'emptyLine': "This is the real summary",
        'module_attr': 'This is a module attribute',
        'C.class_attr': 'This is a class attribute',
        'C.instance_attr': 'This is an instance attribute',
        'C.prop_attr1': 'This is a function docstring',
        'C.prop_attr2': 'This is a attribute docstring',
        'C.C2': 'This is a nested inner class docstring',
    }
    for key, expected in expected_values.items():
        assert autosummary_items[key][2] == expected, 'Summary for %s was %r -'\
            ' expected %r' % (key, autosummary_items[key], expected)

    # check an item in detail
    assert 'func' in autosummary_items
    func_attrs = ('func',
                  '(arg_, *args, **kwargs)',
                  'Test function take an argument ended with underscore.',
                  'dummy_module.func')
    assert autosummary_items['func'] == func_attrs


def str_content(elem):
    if elem.text is not None:
        return elem.text
    else:
        return ''.join(str_content(e) for e in elem)


@pytest.mark.sphinx('xml', **default_kw)
def test_escaping(app, status, warning):
    app.builder.build_all()

    outdir = app.builder.outdir

    docpage = outdir / 'underscore_module_.xml'
    assert docpage.exists()

    title = etree_parse(docpage).find('section/title')

    assert str_content(title) == 'underscore_module_'


@pytest.mark.sphinx(testroot='ext-autosummary')
def test_autosummary_generate_content_for_module(app):
    import autosummary_dummy_module
    template = Mock()

    generate_autosummary_content('autosummary_dummy_module', autosummary_dummy_module, None,
                                 template, None, False, app, False, {})
    assert template.render.call_args[0][0] == 'module'

    context = template.render.call_args[0][1]
    assert context['members'] == ['CONSTANT1', 'CONSTANT2', 'Exc', 'Foo', '_Baz', '_Exc',
                                  '__all__', '__builtins__', '__cached__', '__doc__',
                                  '__file__', '__name__', '__package__', '_quux', 'bar',
                                  'quuz', 'qux']
    assert context['functions'] == ['bar']
    assert context['all_functions'] == ['_quux', 'bar']
    assert context['classes'] == ['Foo']
    assert context['all_classes'] == ['Foo', '_Baz']
    assert context['exceptions'] == ['Exc']
    assert context['all_exceptions'] == ['Exc', '_Exc']
    assert context['attributes'] == ['CONSTANT1', 'qux', 'quuz']
    assert context['all_attributes'] == ['CONSTANT1', 'qux', 'quuz']
    assert context['fullname'] == 'autosummary_dummy_module'
    assert context['module'] == 'autosummary_dummy_module'
    assert context['objname'] == ''
    assert context['name'] == ''
    assert context['objtype'] == 'module'


@pytest.mark.sphinx(testroot='ext-autosummary')
def test_autosummary_generate_content_for_module___all__(app):
    import autosummary_dummy_module
    template = Mock()
    app.config.autosummary_ignore_module_all = False

    generate_autosummary_content('autosummary_dummy_module', autosummary_dummy_module, None,
                                 template, None, False, app, False, {})
    assert template.render.call_args[0][0] == 'module'

    context = template.render.call_args[0][1]
    assert context['members'] == ['CONSTANT1', 'Exc', 'Foo', '_Baz', 'bar', 'qux', 'path']
    assert context['functions'] == ['bar']
    assert context['all_functions'] == ['bar']
    assert context['classes'] == ['Foo']
    assert context['all_classes'] == ['Foo', '_Baz']
    assert context['exceptions'] == ['Exc']
    assert context['all_exceptions'] == ['Exc']
    assert context['attributes'] == ['CONSTANT1', 'qux']
    assert context['all_attributes'] == ['CONSTANT1', 'qux']
    assert context['fullname'] == 'autosummary_dummy_module'
    assert context['module'] == 'autosummary_dummy_module'
    assert context['objname'] == ''
    assert context['name'] == ''
    assert context['objtype'] == 'module'


@pytest.mark.sphinx(testroot='ext-autosummary')
def test_autosummary_generate_content_for_module_skipped(app):
    import autosummary_dummy_module
    template = Mock()

    def skip_member(app, what, name, obj, skip, options):
        if name in ('Foo', 'bar', 'Exc'):
            return True

    app.connect('autodoc-skip-member', skip_member)
    generate_autosummary_content('autosummary_dummy_module', autosummary_dummy_module, None,
                                 template, None, False, app, False, {})
    context = template.render.call_args[0][1]
    assert context['members'] == ['CONSTANT1', 'CONSTANT2', '_Baz', '_Exc', '__all__',
                                  '__builtins__', '__cached__', '__doc__', '__file__',
                                  '__name__', '__package__', '_quux', 'quuz', 'qux']
    assert context['functions'] == []
    assert context['classes'] == []
    assert context['exceptions'] == []


@pytest.mark.sphinx(testroot='ext-autosummary')
def test_autosummary_generate_content_for_module_imported_members(app):
    import autosummary_dummy_module
    template = Mock()

    generate_autosummary_content('autosummary_dummy_module', autosummary_dummy_module, None,
                                 template, None, True, app, False, {})
    assert template.render.call_args[0][0] == 'module'

    context = template.render.call_args[0][1]
    assert context['members'] == ['CONSTANT1', 'CONSTANT2', 'Exc', 'Foo', 'Union', '_Baz',
                                  '_Exc', '__all__', '__builtins__', '__cached__', '__doc__',
                                  '__file__', '__loader__', '__name__', '__package__',
                                  '__spec__', '_quux', 'bar', 'path', 'quuz', 'qux']
    assert context['functions'] == ['bar']
    assert context['all_functions'] == ['_quux', 'bar']
    assert context['classes'] == ['Foo']
    assert context['all_classes'] == ['Foo', '_Baz']
    assert context['exceptions'] == ['Exc']
    assert context['all_exceptions'] == ['Exc', '_Exc']
    assert context['attributes'] == ['CONSTANT1', 'qux', 'quuz']
    assert context['all_attributes'] == ['CONSTANT1', 'qux', 'quuz']
    assert context['fullname'] == 'autosummary_dummy_module'
    assert context['module'] == 'autosummary_dummy_module'
    assert context['objname'] == ''
    assert context['name'] == ''
    assert context['objtype'] == 'module'


@pytest.mark.sphinx('dummy', testroot='ext-autosummary')
def test_autosummary_generate(app, status, warning):
    app.builder.build_all()

    doctree = app.env.get_doctree('index')
    assert_node(doctree, (nodes.paragraph,
                          nodes.paragraph,
                          addnodes.tabular_col_spec,
                          autosummary_table,
                          [autosummary_toc, addnodes.toctree]))
    assert_node(doctree[3],
                [autosummary_table, nodes.table, nodes.tgroup, (nodes.colspec,
                                                                nodes.colspec,
                                                                [nodes.tbody, (nodes.row,
                                                                               nodes.row,
                                                                               nodes.row,
                                                                               nodes.row,
                                                                               nodes.row,
                                                                               nodes.row)])])
    assert_node(doctree[4][0], addnodes.toctree, caption="An autosummary")

    assert len(doctree[3][0][0][2]) == 6
    assert doctree[3][0][0][2][0].astext() == 'autosummary_dummy_module\n\n'
    assert doctree[3][0][0][2][1].astext() == 'autosummary_dummy_module.Foo()\n\n'
    assert doctree[3][0][0][2][2].astext() == 'autosummary_dummy_module.Foo.Bar()\n\n'
    assert doctree[3][0][0][2][3].astext() == 'autosummary_dummy_module.Foo.value\n\ndocstring'
    assert doctree[3][0][0][2][4].astext() == 'autosummary_dummy_module.bar(x[, y])\n\n'
    assert doctree[3][0][0][2][5].astext() == 'autosummary_dummy_module.qux\n\na module-level attribute'

    module = (app.srcdir / 'generated' / 'autosummary_dummy_module.rst').read_text()

    assert ('   .. autosummary::\n'
            '   \n'
            '      Foo\n'
            '   \n' in module)
    assert ('   .. autosummary::\n'
            '   \n'
            '      CONSTANT1\n'
            '      qux\n'
            '      quuz\n'
            '   \n' in module)

    Foo = (app.srcdir / 'generated' / 'autosummary_dummy_module.Foo.rst').read_text()
    assert '.. automethod:: __init__' in Foo
    assert ('   .. autosummary::\n'
            '   \n'
            '      ~Foo.__init__\n'
            '      ~Foo.bar\n'
            '   \n' in Foo)
    assert ('   .. autosummary::\n'
            '   \n'
            '      ~Foo.CONSTANT3\n'
            '      ~Foo.CONSTANT4\n'
            '      ~Foo.baz\n'
            '      ~Foo.value\n'
            '   \n' in Foo)

    FooBar = (app.srcdir / 'generated' / 'autosummary_dummy_module.Foo.Bar.rst').read_text()
    assert ('.. currentmodule:: autosummary_dummy_module\n'
            '\n'
            '.. autoclass:: Foo.Bar\n' in FooBar)

    Foo_value = (app.srcdir / 'generated' / 'autosummary_dummy_module.Foo.value.rst').read_text()
    assert ('.. currentmodule:: autosummary_dummy_module\n'
            '\n'
            '.. autoattribute:: Foo.value' in Foo_value)

    qux = (app.srcdir / 'generated' / 'autosummary_dummy_module.qux.rst').read_text()
    assert ('.. currentmodule:: autosummary_dummy_module\n'
            '\n'
            '.. autodata:: qux' in qux)


@pytest.mark.sphinx('dummy', testroot='ext-autosummary',
                    confoverrides={'autosummary_generate_overwrite': False})
def test_autosummary_generate_overwrite1(app_params, make_app):
    args, kwargs = app_params
    srcdir = kwargs.get('srcdir')

    (srcdir / 'generated').makedirs(exist_ok=True)
    (srcdir / 'generated' / 'autosummary_dummy_module.rst').write_text('')

    app = make_app(*args, **kwargs)
    content = (srcdir / 'generated' / 'autosummary_dummy_module.rst').read_text()
    assert content == ''
    assert 'autosummary_dummy_module.rst' not in app._warning.getvalue()


@pytest.mark.sphinx('dummy', testroot='ext-autosummary',
                    confoverrides={'autosummary_generate_overwrite': True})
def test_autosummary_generate_overwrite2(app_params, make_app):
    args, kwargs = app_params
    srcdir = kwargs.get('srcdir')

    (srcdir / 'generated').makedirs(exist_ok=True)
    (srcdir / 'generated' / 'autosummary_dummy_module.rst').write_text('')

    app = make_app(*args, **kwargs)
    content = (srcdir / 'generated' / 'autosummary_dummy_module.rst').read_text()
    assert content != ''
    assert 'autosummary_dummy_module.rst' not in app._warning.getvalue()


@pytest.mark.sphinx('dummy', testroot='ext-autosummary-recursive')
@pytest.mark.usefixtures("rollback_sysmodules")
def test_autosummary_recursive(app, status, warning):
    sys.modules.pop('package', None)  # unload target module to clear the module cache

    app.build()

    # autosummary having :recursive: option
    assert (app.srcdir / 'generated' / 'package.rst').exists()
    assert (app.srcdir / 'generated' / 'package.module.rst').exists()
    assert (app.srcdir / 'generated' / 'package.module_importfail.rst').exists() is False
    assert (app.srcdir / 'generated' / 'package.package.rst').exists()
    assert (app.srcdir / 'generated' / 'package.package.module.rst').exists()

    # autosummary not having :recursive: option
    assert (app.srcdir / 'generated' / 'package2.rst').exists()
    assert (app.srcdir / 'generated' / 'package2.module.rst').exists() is False

    # Check content of recursively generated stub-files
    content = (app.srcdir / 'generated' / 'package.rst').read_text()
    assert 'package.module' in content
    assert 'package.package' in content
    assert 'package.module_importfail' in content

    content = (app.srcdir / 'generated' / 'package.package.rst').read_text()
    assert 'package.package.module' in content


@pytest.mark.sphinx('dummy', testroot='ext-autosummary-recursive',
                    srcdir='test_autosummary_recursive_skips_mocked_modules',
                    confoverrides={'autosummary_mock_imports': ['package.package']})
@pytest.mark.usefixtures("rollback_sysmodules")
def test_autosummary_recursive_skips_mocked_modules(app, status, warning):
    sys.modules.pop('package', None)  # unload target module to clear the module cache
    app.build()

    assert (app.srcdir / 'generated' / 'package.rst').exists()
    assert (app.srcdir / 'generated' / 'package.module.rst').exists()
    assert (app.srcdir / 'generated' / 'package.package.rst').exists() is False
    assert (app.srcdir / 'generated' / 'package.package.module.rst').exists() is False


@pytest.mark.sphinx('dummy', testroot='ext-autosummary-filename-map')
def test_autosummary_filename_map(app, status, warning):
    app.build()

    assert (app.srcdir / 'generated' / 'module_mangled.rst').exists()
    assert not (app.srcdir / 'generated' / 'autosummary_dummy_module.rst').exists()
    assert (app.srcdir / 'generated' / 'bar.rst').exists()
    assert not (app.srcdir / 'generated' / 'autosummary_dummy_module.bar.rst').exists()
    assert (app.srcdir / 'generated' / 'autosummary_dummy_module.Foo.rst').exists()

    html_warnings = app._warning.getvalue()
    assert html_warnings == ''


@pytest.mark.sphinx('latex', **default_kw)
def test_autosummary_latex_table_colspec(app, status, warning):
    app.builder.build_all()
    result = (app.outdir / 'python.tex').read_text()
    print(status.getvalue())
    print(warning.getvalue())
    assert r'\begin{longtable}[c]{\X{1}{2}\X{1}{2}}' in result
    assert r'p{0.5\linewidth}' not in result


def test_import_by_name():
    import sphinx
    import sphinx.ext.autosummary

    prefixed_name, obj, parent, modname = import_by_name('sphinx')
    assert prefixed_name == 'sphinx'
    assert obj is sphinx
    assert parent is None
    assert modname == 'sphinx'

    prefixed_name, obj, parent, modname = import_by_name('sphinx.ext.autosummary.__name__')
    assert prefixed_name == 'sphinx.ext.autosummary.__name__'
    assert obj is sphinx.ext.autosummary.__name__
    assert parent is sphinx.ext.autosummary
    assert modname == 'sphinx.ext.autosummary'

    prefixed_name, obj, parent, modname = \
        import_by_name('sphinx.ext.autosummary.Autosummary.get_items')
    assert prefixed_name == 'sphinx.ext.autosummary.Autosummary.get_items'
    assert obj == sphinx.ext.autosummary.Autosummary.get_items
    assert parent is sphinx.ext.autosummary.Autosummary
    assert modname == 'sphinx.ext.autosummary'


@pytest.mark.sphinx('dummy', testroot='ext-autosummary-mock_imports')
def test_autosummary_mock_imports(app, status, warning):
    try:
        app.build()
        assert warning.getvalue() == ''

        # generated/foo is generated successfully
        assert app.env.get_doctree('generated/foo')
    finally:
        sys.modules.pop('foo', None)  # unload foo module


@pytest.mark.sphinx('dummy', testroot='ext-autosummary-imported_members')
def test_autosummary_imported_members(app, status, warning):
    try:
        app.build()
        # generated/foo is generated successfully
        assert app.env.get_doctree('generated/autosummary_dummy_package')

        module = (app.srcdir / 'generated' / 'autosummary_dummy_package.rst').read_text()
        assert ('   .. autosummary::\n'
                '   \n'
                '      Bar\n'
                '   \n' in module)
        assert ('   .. autosummary::\n'
                '   \n'
                '      foo\n'
                '   \n' in module)
    finally:
        sys.modules.pop('autosummary_dummy_package', None)

@pytest.mark.sphinx('dummy', testroot='ext-autosummary-imported_members')
def test_autosummary_imported_members_table_10058(app, status, warning):
    try:
        #app.env.config.autodoc_class_signature = 'separated'
        app.build()

        doctree = app.env.get_doctree('index')

        assert_node(doctree, (nodes.section,))
                            # nodes.paragraph,
                            # addnodes.tabular_col_spec,
                            # autosummary_table,
                            # [autosummary_toc, addnodes.toctree]))
        assert_node(doctree[0], (
            nodes.title,
            addnodes.tabular_col_spec,
            autosummary_table,
            autosummary_toc,
            addnodes.tabular_col_spec,
            autosummary_table
        ))

        table = list(doctree[0].traverse(autosummary_table))[1]

        assert_node(table, [
            autosummary_table,
            nodes.table,
            nodes.tgroup,
            (nodes.colspec, nodes.colspec, nodes.tbody)
        ])

        tbody = table.next_node(nodes.tbody)

        assert_node(tbody, (
            [nodes.row, (nodes.entry, nodes.entry)],
            [nodes.row, (nodes.entry, nodes.entry)]
        ))

        assert 'foo' in tbody[0][0].next_node(nodes.Text).astext()
        assert 'Bar' in tbody[1][0].next_node(nodes.Text).astext()

    finally:
        sys.modules.pop('autosummary_dummy_package', None)


@pytest.mark.sphinx(testroot='ext-autodoc',
                    confoverrides={'extensions': ['sphinx.ext.autosummary']})
def test_generate_autosummary_docs_property(app):
    with patch('sphinx.ext.autosummary.generate.find_autosummary_in_files') as mock:
        mock.return_value = [AutosummaryEntry('target.methods.Base.prop', 'prop', None, False)]
        generate_autosummary_docs([], output_dir=app.srcdir, app=app)

    content = (app.srcdir / 'target.methods.Base.prop.rst').read_text()
    assert content == ("target.methods.Base.prop\n"
                       "========================\n"
                       "\n"
                       ".. currentmodule:: target.methods\n"
                       "\n"
                       ".. autoproperty:: Base.prop")


@pytest.mark.sphinx(testroot='ext-autosummary-skip-member')
def test_autosummary_skip_member(app):
    app.build()

    content = (app.srcdir / 'generate' / 'target.Foo.rst').read_text()
    assert 'Foo.skipmeth' not in content
    assert 'Foo._privatemeth' in content


@pytest.mark.sphinx(testroot='ext-autosummary-template')
def test_autosummary_template(app):
    app.build()

    content = (app.srcdir / 'generate' / 'target.Foo.rst').read_text()
    assert 'EMPTY' in content


@pytest.mark.sphinx('dummy', testroot='ext-autosummary',
                    confoverrides={'autosummary_generate': []})
def test_empty_autosummary_generate(app, status, warning):
    app.build()
    assert ("WARNING: autosummary: failed to import autosummary_importfail"
            in warning.getvalue())


@pytest.mark.sphinx('dummy', testroot='ext-autosummary',
                    confoverrides={'autosummary_generate': ['unknown']})
def test_invalid_autosummary_generate(app, status, warning):
    assert 'WARNING: autosummary_generate: file not found: unknown.rst' in warning.getvalue()


def test_autogen(rootdir, tempdir):
    with cd(rootdir / 'test-templating'):
        args = ['-o', tempdir, '-t', '.', 'autosummary_templating.txt']
        autogen_main(args)
        assert (tempdir / 'sphinx.application.TemplateBridge.rst').exists()