🐛 FIX: parse front matter closed by the YAML ... marker

mdit_py_plugins/front_matter/index.py

@@ -69,12 +69,19 @@ def _front_matter_rule(
             # unclosed block should be autoclosed by end of document.
             return False
 
-        if state.src[start:maximum] == "...":
-            break
-
         start = state.bMarks[nextLine] + state.tShift[nextLine]
         maximum = state.eMarks[nextLine]
 
+        if (
+            state.sCount[nextLine] == 0
+            and state.src.startswith("...", start)
+            and state.skipSpaces(start + 3) >= maximum
+        ):
+            # YAML document-end marker: `...` at column 0, trailing spaces allowed.
+            # It is checked on the current line and consumed, so it is not content.
+            auto_closed = True
+            break
+
         if start < maximum and state.sCount[nextLine] < state.blkIndent:
             # non-empty line with negative indent should stop the list:
             # - ```

tests/fixtures/front_matter.md

@@ -32,6 +32,61 @@ x: 1
 <h1>Head</h1>
 .
 
+should parse triple dots at end of document:
+.
+---
+x: 1
+...
+.
+.
+
+should ignore spaces after triple dots:
+.
+---
+x: 1
+...   
+# Head
+.
+
+<h1>Head</h1>
+.
+
+should not close on indented triple dots:
+.
+---
+text: |
+  ...
+---
+# Head
+.
+
+<h1>Head</h1>
+.
+
+should not close on four dots:
+.
+---
+x: 1
+....
+---
+# Head
+.
+
+<h1>Head</h1>
+.
+
+should not close on triple dots followed by text:
+.
+---
+x: 1
+...x
+---
+# Head
+.
+
+<h1>Head</h1>
+.
+
 should parse front matter with indentation:
 .
 ---

tests/test_front_matter.py

@@ -42,6 +42,30 @@ def test_token():
     ]
 
 
+@pytest.mark.parametrize("closer", ["---", "...", "...   "])
+def test_token_content_excludes_the_closer(closer):
+    """The closing marker must not be left inside the extracted content.
+
+    ``...`` is the YAML document-end marker and is exercised by the fixture file,
+    so it has to be consumed like the dashed form rather than kept in the block.
+    """
+    md = MarkdownIt("commonmark").use(front_matter_plugin)
+    tokens = md.parse(f"---\na: 1\n{closer}")
+    assert [token.type for token in tokens] == ["front_matter"]
+    assert tokens[0].content == "a: 1"
+
+
+def test_dots_closer_on_the_last_line():
+    """A block closed by ``...`` on the final line is still front matter.
+
+    ``test_all`` cannot see this: the front_matter token is hidden, so only the
+    rendered output is asserted, and a block that is dropped rather than closed
+    renders as visible text instead of disappearing.
+    """
+    md = MarkdownIt("commonmark").use(front_matter_plugin)
+    assert md.render("---\na: 1\n...\n") == md.render("---\na: 1\n---\n") == ""
+
+
 def test_short_source():
     md = MarkdownIt("commonmark").use(front_matter_plugin)