Preserve task markers in indented list code

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+* 🐛 Preserve literal task-list markers in indented code blocks inside list items.
 * ✨ Add `--enable-tables` to the CLI for file, standard input and interactive parsing in [#422](https://github.com/executablebooks/markdown-it-py/pull/422)
 * 🐛 Fix CLI interactive mode joining input lines with an extra newline, which split every line into its own paragraph and broke hard line breaks, in [#172](https://github.com/executablebooks/markdown-it-py/issues/172)
 * 🐛 Fix trimming and splitting with the Python whitespace set instead of the CommonMark one, which dropped U+001C–U+001F and U+0085 from paragraphs, headings, table cells and fence info strings and let distinct reference labels resolve each other, in [#418](https://github.com/executablebooks/markdown-it-py/pull/418), thanks to [@Nexory](https://github.com/Nexory)

markdown_it/rules_block/list.py

@@ -235,17 +235,6 @@ def list_block(state: StateBlock, startLine: int, endLine: int, silent: bool) ->
         if isOrdered:
             token.info = state.src[start : posAfterMarker - 1]
 
-        # Detect GFM task checkbox: `[ ] ` or `[x] `/`[X] ` at content start
-        checkboxLen = 0
-        if state.md.options.get("tasklists", False) and contentStart < maximum:
-            checked = _detect_task_checkbox(state.src, contentStart, maximum)
-            if checked is not None:
-                token.meta = {"checked": checked}
-                # Advance content past the checkbox: `[x]` (3 chars) + whitespace.
-                # `_detect_task_checkbox` already guarantees a whitespace char at
-                # pos+3, so we always consume 4 characters.
-                checkboxLen = 4
-
         # change current state, then restore it after parser subcall
         oldTight = state.tight
         oldBMark = state.bMarks[startLine]
@@ -264,6 +253,22 @@ def list_block(state: StateBlock, startLine: int, endLine: int, silent: bool) ->
         state.tShift[startLine] = contentStart - state.bMarks[startLine]
         state.sCount[startLine] = offset
 
+        # Detect GFM task checkboxes only after setting the item's indentation,
+        # so literal markers in indented code blocks are left untouched.
+        checkboxLen = 0
+        if (
+            state.md.options.get("tasklists", False)
+            and contentStart < maximum
+            and not state.is_code_block(startLine)
+        ):
+            checked = _detect_task_checkbox(state.src, contentStart, maximum)
+            if checked is not None:
+                token.meta = {"checked": checked}
+                # Advance content past the checkbox: `[x]` (3 chars) + whitespace.
+                # `_detect_task_checkbox` already guarantees a whitespace char at
+                # pos+3, so we always consume 4 characters.
+                checkboxLen = 4
+
         # If we detected a checkbox, advance bMarks past it so that
         # getLines() doesn't include the checkbox text in the content.
         if checkboxLen:

tests/test_port/test_misc.py

@@ -1,3 +1,5 @@
+import pytest
+
 from markdown_it import MarkdownIt, presets
 
 
@@ -42,3 +44,47 @@ def type_filter(tokens, type_):
     assert tokens[2].markup == "."
     assert tokens[3].info == "199"
     assert tokens[3].markup == "."
+
+
+@pytest.mark.parametrize("editable", [False, True])
+@pytest.mark.parametrize(
+    "source,code",
+    [
+        ("-     [x] literal\n", "[x] literal\n"),
+        ("-      [ ] literal\n", " [ ] literal\n"),
+        ("1.     [X] literal\n", "[X] literal\n"),
+        ("-\t\t[x] literal\n", "  [x] literal\n"),
+        ("> -     [X] literal\n", "[X] literal\n"),
+        ("- outer\n  -     [ ] literal\n", "[ ] literal\n"),
+    ],
+)
+def test_task_marker_in_indented_code(source, code, editable):
+    """Task detection must preserve literal markers and indentation in code."""
+    md = MarkdownIt("gfm-like2", {"tasklists_editable": editable})
+    tokens = md.parse(source)
+    assert [token.content for token in tokens if token.type == "code_block"] == [code]
+    assert all("checked" not in token.meta for token in tokens)
+    assert md.render(source) == MarkdownIt("gfm-like2", {"tasklists": False}).render(
+        source
+    )
+
+
+@pytest.mark.parametrize("spacing", [" ", "    ", "\t"])
+@pytest.mark.parametrize("code_enabled", [False, True])
+def test_task_marker_in_paragraph(spacing, code_enabled):
+    """Keep recognizing tasks up to the paragraph indentation boundary."""
+    md = MarkdownIt("gfm-like2")
+    if not code_enabled:
+        md.disable("code")
+    tokens = md.parse(f"-{spacing}[x] task\n")
+    item = next(token for token in tokens if token.type == "list_item_open")
+    assert item.meta["checked"] is True
+    assert not any(token.type == "code_block" for token in tokens)
+
+
+def test_indented_task_marker_with_code_disabled():
+    """Without the code rule, the indented text is still eligible for a task."""
+    md = MarkdownIt("gfm-like2").disable("code")
+    tokens = md.parse("-     [x] task\n")
+    item = next(token for token in tokens if token.type == "list_item_open")
+    assert item.meta["checked"] is True