memo_test.py

# Copyright 2018-2021 Streamlit Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""st.memo unit tests."""
import pickle
import re
import unittest
from unittest.mock import patch, mock_open, MagicMock

import streamlit as st
from streamlit import StreamlitAPIException, file_util
from streamlit.caching import memo_decorator, clear_memo_cache
from streamlit.caching.cache_errors import CacheError
from streamlit.caching.memo_decorator import get_cache_path


class MemoTest(unittest.TestCase):
    def tearDown(self):
        # Some of these tests reach directly into _cache_info and twiddle it.
        # Reset default values on teardown.
        memo_decorator.MEMO_CALL_STACK._cached_func_stack = []
        memo_decorator.MEMO_CALL_STACK._suppress_st_function_warning = 0
        super().tearDown()

    @patch.object(st, "exception")
    def test_mutate_return(self, exception):
        """Mutating a memoized return value is legal, and *won't* affect
        future accessors of the data."""

        @st.experimental_memo
        def f():
            return [0, 1]

        r1 = f()

        r1[0] = 1

        r2 = f()

        exception.assert_not_called()

        self.assertEqual(r1, [1, 1])
        self.assertEqual(r2, [0, 1])


class MemoPersistTest(unittest.TestCase):
    """st.memo disk persistence tests"""

    @patch("streamlit.caching.memo_decorator.streamlit_write")
    def test_dont_persist_by_default(self, mock_write):
        @st.experimental_memo
        def foo():
            return "data"

        foo()
        mock_write.assert_not_called()

    @patch("streamlit.caching.memo_decorator.streamlit_write")
    def test_persist_path(self, mock_write):
        """Ensure we're writing to ~/.streamlit/memo"""

        @st.experimental_memo(persist="disk")
        def foo():
            return "data"

        foo()
        mock_write.assert_called_once()

        write_path = mock_write.call_args[0][0]
        match = re.fullmatch(
            r"/mock/home/folder/.streamlit/cache/.*?\.memo", write_path
        )
        self.assertIsNotNone(match)

    @patch("streamlit.file_util.os.stat", MagicMock())
    @patch(
        "streamlit.file_util.get_streamlit_file_path",
        MagicMock(return_value="/cache/file"),
    )
    @patch(
        "streamlit.file_util.open",
        mock_open(read_data=pickle.dumps("mock_pickled_value")),
    )
    @patch(
        "streamlit.caching.memo_decorator.streamlit_read",
        wraps=file_util.streamlit_read,
    )
    def test_read_persisted_data(self, mock_read):
        """We should read persisted data from disk on cache miss."""

        @st.experimental_memo(persist="disk")
        def foo():
            return "actual_value"

        data = foo()
        mock_read.assert_called_once()
        self.assertEqual("mock_pickled_value", data)

    @patch("streamlit.file_util.os.stat", MagicMock())
    @patch(
        "streamlit.file_util.get_streamlit_file_path",
        MagicMock(return_value="/cache/file"),
    )
    @patch("streamlit.file_util.open", mock_open(read_data="bad_pickled_value"))
    @patch(
        "streamlit.caching.memo_decorator.streamlit_read",
        wraps=file_util.streamlit_read,
    )
    def test_read_bad_persisted_data(self, mock_read):
        """If our persisted data is bad, we raise an exception."""

        @st.experimental_memo(persist="disk")
        def foo():
            return "actual_value"

        with self.assertRaises(CacheError) as error:
            foo()
        mock_read.assert_called_once()
        self.assertEqual("Unable to read from cache", str(error.exception))

    def test_bad_persist_value(self):
        with self.assertRaises(StreamlitAPIException) as e:

            @st.experimental_memo(persist="yesplz")
            def foo():
                pass

        self.assertEqual(
            "Unsupported persist option 'yesplz'. Valid values are 'disk' or None.",
            str(e.exception),
        )

    @patch("shutil.rmtree")
    def test_clear_disk_cache(self, mock_rmtree):
        """`clear_all` should remove the disk cache directory if it exists."""

        # If the cache dir exists, we should delete it.
        with patch("os.path.isdir", MagicMock(return_value=True)):
            clear_memo_cache()
            mock_rmtree.assert_called_once_with(get_cache_path())

        mock_rmtree.reset_mock()

        # If the cache dir does not exist, we shouldn't try to delete it.
        with patch("os.path.isdir", MagicMock(return_value=False)):
            clear_memo_cache()
            mock_rmtree.assert_not_called()