1 files changed, 208 insertions, 0 deletions
diff --git a/tests/bot/utils/test_message_cache.py b/tests/bot/utils/test_message_cache.py
new file mode 100644
index 000000000..ff313c6d6
--- /dev/null
+++ b/tests/bot/utils/test_message_cache.py
@@ -0,0 +1,208 @@
+import unittest
+
+from bot.utils.message_cache import MessageCache
+from tests.helpers import MockMessage
+
+
+# noinspection SpellCheckingInspection
+class TestMessageCache(unittest.TestCase):
+    """Tests for the MessageCache class in the `bot.utils.caching` module."""
+
+    def test_first_append_sets_the_first_value(self):
+        """Test if the first append adds the message to the first cell."""
+        cache = MessageCache(maxlen=10)
+        message = MockMessage()
+
+        cache.append(message)
+
+        self.assertEqual(cache[0], message)
+
+    def test_append_adds_in_the_right_order(self):
+        """Test if two appends are added in the same order if newest_first is False, or in reverse order otherwise."""
+        messages = [MockMessage(), MockMessage()]
+
+        cache = MessageCache(maxlen=10, newest_first=False)
+        for msg in messages:
+            cache.append(msg)
+        self.assertListEqual(messages, list(cache))
+
+        cache = MessageCache(maxlen=10, newest_first=True)
+        for msg in messages:
+            cache.append(msg)
+        self.assertListEqual(messages[::-1], list(cache))
+
+    def test_appending_over_maxlen_removes_oldest(self):
+        """Test if three appends to a 2-cell cache leave the two newest messages."""
+        cache = MessageCache(maxlen=2)
+        messages = [MockMessage() for _ in range(3)]
+
+        for msg in messages:
+            cache.append(msg)
+
+        self.assertListEqual(messages[1:], list(cache))
+
+    def test_appending_over_maxlen_with_newest_first_removes_oldest(self):
+        """Test if three appends to a 2-cell cache leave the two newest messages if newest_first is True."""
+        cache = MessageCache(maxlen=2, newest_first=True)
+        messages = [MockMessage() for _ in range(3)]
+
+        for msg in messages:
+            cache.append(msg)
+
+        self.assertListEqual(messages[:0:-1], list(cache))
+
+    def test_pop_removes_from_the_end(self):
+        """Test if a pop removes the right-most message."""
+        cache = MessageCache(maxlen=3)
+        messages = [MockMessage() for _ in range(3)]
+
+        for msg in messages:
+            cache.append(msg)
+        msg = cache.pop()
+
+        self.assertEqual(msg, messages[-1])
+        self.assertListEqual(messages[:-1], list(cache))
+
+    def test_popleft_removes_from_the_beginning(self):
+        """Test if a popleft removes the left-most message."""
+        cache = MessageCache(maxlen=3)
+        messages = [MockMessage() for _ in range(3)]
+
+        for msg in messages:
+            cache.append(msg)
+        msg = cache.popleft()
+
+        self.assertEqual(msg, messages[0])
+        self.assertListEqual(messages[1:], list(cache))
+
+    def test_clear(self):
+        """Test if a clear makes the cache empty."""
+        cache = MessageCache(maxlen=5)
+        messages = [MockMessage() for _ in range(3)]
+
+        for msg in messages:
+            cache.append(msg)
+        cache.clear()
+
+        self.assertListEqual(list(cache), [])
+        self.assertEqual(len(cache), 0)
+
+    def test_get_message_returns_the_message(self):
+        """Test if get_message returns the cached message."""
+        cache = MessageCache(maxlen=5)
+        message = MockMessage(id=1234)
+
+        cache.append(message)
+
+        self.assertEqual(cache.get_message(1234), message)
+
+    def test_get_message_returns_none(self):
+        """Test if get_message returns None for an ID of a non-cached message."""
+        cache = MessageCache(maxlen=5)
+        message = MockMessage(id=1234)
+
+        cache.append(message)
+
+        self.assertIsNone(cache.get_message(4321))
+
+    def test_update_replaces_old_element(self):
+        """Test if an update replaced the old message with the same ID."""
+        cache = MessageCache(maxlen=5)
+        message = MockMessage(id=1234)
+
+        cache.append(message)
+        message = MockMessage(id=1234)
+        cache.update(message)
+
+        self.assertIs(cache.get_message(1234), message)
+        self.assertEqual(len(cache), 1)
+
+    def test_contains_returns_true_for_cached_message(self):
+        """Test if contains returns True for an ID of a cached message."""
+        cache = MessageCache(maxlen=5)
+        message = MockMessage(id=1234)
+
+        cache.append(message)
+
+        self.assertIn(1234, cache)
+
+    def test_contains_returns_false_for_non_cached_message(self):
+        """Test if contains returns False for an ID of a non-cached message."""
+        cache = MessageCache(maxlen=5)
+        message = MockMessage(id=1234)
+
+        cache.append(message)
+
+        self.assertNotIn(4321, cache)
+
+    def test_indexing(self):
+        """Test if the cache returns the correct messages by index."""
+        cache = MessageCache(maxlen=5)
+        messages = [MockMessage() for _ in range(5)]
+
+        for msg in messages:
+            cache.append(msg)
+
+        for current_loop in range(-5, 5):
+            with self.subTest(current_loop=current_loop):
+                self.assertEqual(cache[current_loop], messages[current_loop])
+
+    def test_bad_index_raises_index_error(self):
+        """Test if the cache raises IndexError for invalid indices."""
+        cache = MessageCache(maxlen=5)
+        messages = [MockMessage() for _ in range(3)]
+        test_cases = (-10, -4, 3, 4, 5)
+
+        for msg in messages:
+            cache.append(msg)
+
+        for current_loop in test_cases:
+            with self.subTest(current_loop=current_loop):
+                with self.assertRaises(IndexError):
+                    cache[current_loop]
+
+    def test_slicing_with_unfilled_cache(self):
+        """Test if slicing returns the correct messages if the cache is not yet fully filled."""
+        cache = MessageCache(maxlen=5)
+        messages = [MockMessage() for _ in range(4)]
+
+        for msg in messages:
+            cache.append(msg)
+
+        test_cases = (
+            slice(None), slice(2, None), slice(None, 2), slice(None, None, 2), slice(None, None, 3), slice(-1, 2),
+            slice(-1, 3000), slice(-3, -1), slice(-10, 3), slice(-10, 4, 2), slice(None, None, -1), slice(None, 3, -2),
+            slice(None, None, -3)
+        )
+
+        for current_loop in test_cases:
+            with self.subTest(current_loop=current_loop):
+                self.assertListEqual(cache[current_loop], messages[current_loop])
+
+    def test_slicing_with_overfilled_cache(self):
+        """Test if slicing returns the correct messages if the cache was appended with more messages it can contain."""
+        cache = MessageCache(maxlen=5)
+        messages = [MockMessage() for _ in range(8)]
+
+        for msg in messages:
+            cache.append(msg)
+        messages = messages[3:]
+
+        test_cases = (
+            slice(None), slice(2, None), slice(None, 2), slice(None, None, 2), slice(None, None, 3), slice(-1, 2),
+            slice(-1, 3000), slice(-3, -1), slice(-10, 3), slice(-10, 4, 2), slice(None, None, -1), slice(None, 3, -2),
+            slice(None, None, -3)
+        )
+
+        for current_loop in test_cases:
+            with self.subTest(current_loop=current_loop):
+                self.assertListEqual(cache[current_loop], messages[current_loop])
+
+    def test_length(self):
+        """Test if len returns the correct number of items in the cache."""
+        cache = MessageCache(maxlen=5)
+
+        for current_loop in range(10):
+            with self.subTest(current_loop=current_loop):
+                self.assertEqual(len(cache), min(current_loop, 5))
+                cache.append(MockMessage())