Backward compatibility with #419

jupytext/cell_reader.py

@@ -444,11 +444,20 @@ def find_cell_end(self, lines):
                     prev_blank = 0
         else:
             self.cell_type = "code"
+            # At some point we could remove the below, in which we make sure not to break language strings
+            # into multiple cells (#419). Indeed, now that the markdown cell uses one extra backtick (#712)
+            # we should not have the issue any more
+            parser = StringParser(self.language or self.default_language)
             for i, line in enumerate(lines):
                 # skip cell header
                 if i == 0:
                     continue
 
+                if parser.is_quoted():
+                    parser.read_line(line)
+                    continue
+
+                parser.read_line(line)
                 if self.end_code_re.match(line):
                     return i, i + 1, True
 

tests/test_read_simple_markdown.py

@@ -766,7 +766,7 @@ def test_two_markdown_cell_with_no_language_code_works(
 
 
 def test_markdown_cell_with_code_inside_multiline_string_419(
-    text='''````python
+    text='''```python
 readme = """
 above
 
@@ -776,11 +776,12 @@ def test_markdown_cell_with_code_inside_multiline_string_419(
 
 below
 """
-````
+```
 ''',
 ):
+    """A code cell containing triple backticks is converted to a code cell encapsulated with four backticks"""
     nb = jupytext.reads(text, "md")
-    compare(jupytext.writes(nb, "md"), text)
+    compare(jupytext.writes(nb, "md"), "`" + text[:-1] + "`\n")
     assert len(nb.cells) == 1