Fix code blocks in Slack messages

examples/slackbot/.dockerignore

@@ -36,6 +36,9 @@ share/python-wheels/
 pip-log.txt
 pip-delete-this-directory.txt
 
+# Exclude unit tests
+tests/
+
 # Unit test / coverage reports
 htmlcov/
 .tox/

examples/slackbot/src/slackbot/slack.py

@@ -90,26 +90,88 @@ def to_slack_link(match: re.Match[str]) -> str:
     )
 
 
+def transform_code_block(text: str) -> str:
+    """
+    Remove the language specifier from a Markdown code block.
+    Slack does not support language-specific code blocks.
+
+    Example:
+        ```python
+        print("Hello, World!")
+        ```
+
+        becomes:
+        ```
+        print("Hello, World!")
+        ```
+    """
+    # Remove the language specifier from the code block
+    code_block_pattern = r"```(?:\w+)?(.*?)```"
+
+    return re.sub(code_block_pattern, r"```\1```", text, flags=re.DOTALL)
+
+
+class SlackMessage:
+    """
+    Handles transformation of Markdown to Slack-formatted messages.
+    """
+
+    _transforms = [
+        convert_md_links_to_slack,
+        transform_code_block,
+    ]
+
+    def __init__(self, text: str, channel_id=None, ts=None, thread_ts=None, attachments=None):
+        self.text = text
+        self.channel = channel_id
+        self.ts = ts
+        self.thread_ts = thread_ts
+        self.attachments = attachments or []
+
+    @staticmethod
+    async def from_message(channel_id: str, ts: str):
+        text = await fetch_current_message_text(channel_id, ts)
+        return SlackMessage(text, channel_id=channel_id, ts=ts)
+
+    def _get_transformed_text(self) -> str:
+        t = self.text
+        for fn in self._transforms:
+            t = fn(t)
+        return t
+
+    def append(self, text, delimiter="\n\n"):
+        self.text = f"{self.text}{delimiter}{text}"
+
+    def json(self):
+        return {
+            k: v for k, v in {
+                "text": self._get_transformed_text(),
+                "channel": self.channel,
+                "ts": self.ts,
+                "thread_ts": self.thread_ts,
+                "attachments": self.attachments or None,
+            }.items() if v is not None
+        }
+
+
 async def post_slack_message(
     message: str,
     channel_id: str,
     attachments: list[dict[str, Any]] | None = None,
     thread_ts: str | None = None,
 ) -> httpx.Response:
-    post_data = {
-        "channel": channel_id,
-        "text": convert_md_links_to_slack(message),
-        "attachments": attachments if attachments else [],
-    }
-
-    if thread_ts:
-        post_data["thread_ts"] = thread_ts
+    message = SlackMessage(
+        message,
+        channel_id=channel_id,
+        attachments=attachments,
+        thread_ts=thread_ts,
+    )
 
     async with httpx.AsyncClient() as client:
         response = await client.post(
             "https://slack.com/api/chat.postMessage",
             headers={"Authorization": f"Bearer {settings.slack_api_token}"},
-            json=post_data,
+            json=message.json(),
         )
         response_data = response.json()
 
@@ -187,28 +249,29 @@ async def edit_slack_message(
     """Edit an existing Slack message by appending new text or replacing it.
 
     Args:
-        channel (str): The Slack channel ID.
-        ts (str): The timestamp of the message to edit.
+        channel_id (str): The Slack channel ID.
+        thread_ts (str): The timestamp of the message to edit.
         new_text (str): The new text to append or replace in the message.
         mode (str): The mode of text editing, 'append' (default) or 'replace'.
+        delimiter (Union[str, None]): The delimiter to use if appending to an
+            existing message.
 
     Returns:
         httpx.Response: The response from the Slack API.
     """
     if mode == "append":
-        current_text = await fetch_current_message_text(channel_id, thread_ts)
-        delimiter = "\n\n" if delimiter is None else delimiter
-        updated_text = f"{current_text}{delimiter}{convert_md_links_to_slack(new_text)}"
+        message = await SlackMessage.from_message(channel_id, thread_ts)
+        message.append(new_text, delimiter=delimiter)
     elif mode == "replace":
-        updated_text = convert_md_links_to_slack(new_text)
+        message = SlackMessage(new_text)
     else:
         raise ValueError("Invalid mode. Use 'append' or 'replace'.")
 
     async with httpx.AsyncClient() as client:
         response = await client.post(
             "https://slack.com/api/chat.update",
             headers={"Authorization": f"Bearer {settings.slack_api_token}"},
-            json={"channel": channel_id, "ts": thread_ts, "text": updated_text},
+            json=message.json(),
         )
 
     response.raise_for_status()

examples/slackbot/tests/test_slack_message_class.py

@@ -0,0 +1,73 @@
+import os
+import unittest
+from unittest import mock
+
+@mock.patch.dict(os.environ, {"MARVIN_SLACKBOT_SLACK_API_TOKEN": "xoxb-fake"})
+class SlackMessageClassTests(unittest.TestCase):
+    def test_transforms_code_text(self):
+        from slackbot.slack import SlackMessage
+
+        code = """```python
+        print(test)
+        ```"""
+
+        message = SlackMessage(code)
+
+        expected = """```
+        print(test)
+        ```"""
+
+        self.assertEqual(expected, message._get_transformed_text())
+
+    def test_append(self):
+        from slackbot.slack import SlackMessage
+
+        code = "Original message"
+
+        message = SlackMessage(code)
+        message.append("Updated text")
+
+        expected = "Original message\n\nUpdated text"
+
+        self.assertEqual(expected, message.json()["text"])
+
+    def test_correct_attributes(self):
+        from slackbot.slack import SlackMessage
+        text = "Test message"
+        code = """```python
+        print(test)
+        ```"""
+        code_output = """```
+        print(test)
+        ```"""
+
+        message = SlackMessage(text)
+        attributes = {
+            "text": text
+        }
+        self.assertEqual(attributes, message.json())
+
+        message = SlackMessage(text, channel_id=1, ts=1234567890)
+        attributes = {
+            "text": text,
+            "channel": 1,
+            "ts": 1234567890
+        }
+        self.assertEqual(attributes, message.json())
+
+        message = SlackMessage(text, channel_id=1, thread_ts=1234567890)
+        attributes = {
+            "text": text,
+            "channel": 1,
+            "thread_ts": 1234567890
+        }
+        self.assertEqual(attributes, message.json())
+
+        message = SlackMessage(code, channel_id=1, thread_ts=1234567890)
+        attributes = {
+            "text": code_output,
+            "channel": 1,
+            "thread_ts": 1234567890
+        }
+        self.assertEqual(attributes, message.json())
+