fix: publishDiagnostics starts at 0 and newlines are counted correctly

pylsp/python_lsp.py

@@ -429,8 +429,7 @@ def _lint_notebook_document(self, notebook_document, workspace):   # pylint: dis
             if offset == 0:
                 total_source = cell_document.source
             else:
-                maybe_newline = "" if total_source.endswith("\n") else "\n"
-                total_source += (maybe_newline + cell_document.source)
+                total_source += ("\n" + cell_document.source)
 
             offset += num_lines
 

pylsp/workspace.py

@@ -519,19 +519,5 @@ def __init__(self, uri, language_id, workspace, source=None, version=None, local
     @property
     @lock
     def line_count(self):
-        """"
-        Return the number of lines in the cell document.
-
-        This function is used to combine all cell documents into one text document. Note that we need to count a
-        newline at the end of a non-empty text line as an extra line.
-
-        Examples:
-            - "x\n" is a cell with two lines, "x" and ""
-            - "x" is a cell with one line, "x"
-            - "\n" is a cell with one line, ""
-        """
-        if len(self.lines) == 0:
-            return 1
-
-        last_line = self.lines[-1]
-        return len(self.lines) + (last_line != "\n" and last_line.endswith("\n"))
+        """"Return the number of lines in the cell document."""
+        return len(self.source.split('\n'))

test/test_notebook_document.py

@@ -169,8 +169,8 @@ def test_notebook_document__did_open(
                         {
                             "source": "pyflakes",
                             "range": {
-                                "start": {"line": 0, "character": 0},
-                                "end": {"line": 0, "character": 11},
+                                "start": {"line": 1, "character": 0},
+                                "end": {"line": 1, "character": 11},
                             },
                             "message": "'sys' imported but unused",
                             "severity": 2,
@@ -190,7 +190,7 @@ def test_notebook_document__did_open(
                                 "start": {"line": 1, "character": 0},
                                 "end": {"line": 1, "character": 11},
                             },
-                            "message": "E303 too many blank lines (3)",
+                            "message": "E303 too many blank lines (4)",
                             "code": "E303",
                             "severity": 2,
                         },