fixups

nbqa/__main__.py

@@ -618,10 +618,7 @@ def _main(cli_args: CLIArgs, configs: Configs) -> int:
     try:  # pylint disable=R0912
 
         if not nb_to_tmp_mapping:
-            sys.stderr.write(
-                "No notebooks found in given directories: "
-                f"{' '.join(i for i in cli_args.root_dirs if os.path.isdir(i))}\n"
-            )
+            sys.stderr.write("No notebooks found in given path(s)\n")
             return 0
         saved_sources = SAVE_SOURCES[configs["md"]](
             nb_to_tmp_mapping,

nbqa/path_utils.py

@@ -2,7 +2,7 @@
 import json
 import os
 from pathlib import Path
-from typing import Tuple
+from typing import Any, Dict, Optional, Tuple
 
 
 def remove_prefix(string: str, prefix: str) -> str:
@@ -61,42 +61,53 @@ def get_relative_and_absolute_paths(path: str) -> Tuple[str, str]:
     return str(relative_path), str(absolute_path)
 
 
-def read_notebook(notebook):
+def read_notebook(notebook: str) -> Tuple[Optional[Dict[str, Any]], Optional[bool]]:
+    """
+    Read notebook.
+
+    If it's .md, try reading it with jupytext. If can't, ignore it.
+
+    Parameters
+    ----------
+    notebook
+        Path of notebook.
+
+    Returns
+    -------
+    notebook_json
+        Parsed notebook
+    trailing_newline
+        Whether the notebook originally had a trailing newline
+    """
     trailing_newline = True
     _, ext = os.path.splitext(notebook)
     with open(notebook, encoding="utf-8") as handle:
         content = handle.read()
     if ext == ".ipynb":
         trailing_newline = content.endswith("\n")
         return json.loads(content), trailing_newline
-    elif ext == ".md":
-        try:
-            import jupytext
-        except ImportError:
-            return None, None
-        md_content = jupytext.jupytext.read(notebook)
-
-        # get lexer: see https://github.com/mwouts/jupytext/issues/993
-        from markdown_it import MarkdownIt  # must be installed if you have jupytext
-
-        parser = (
-            MarkdownIt("commonmark")
-            # we only need to parse block level components (for efficiency)
-            .disable("inline", True)
-        )
-        parsed = parser.parse(content)
-        lexer = None
-        for token in parsed:
-            if token.type == "fence" and token.info.startswith("{code-cell}"):
-                lexer = remove_prefix(
-                    parser.parse(content)[4].info, "{code-cell}"
-                ).strip()
-                md_content["metadata"]["language_info"] = {"pygments_lexer": lexer}
-                break
-
-        for cell in md_content["cells"]:
-            cell["source"] = cell["source"].splitlines(keepends=True)
-        if "format_name" in md_content.get("metadata", {}).get("jupytext", {}).get(
-            "text_representation", {}
-        ):
-            return md_content, True
+    assert ext == ".md"
+    try:
+        import jupytext  # pylint: disable=import-outside-toplevel
+        from markdown_it import MarkdownIt  # pylint: disable=import-outside-toplevel
+    except ImportError:
+        return None, None
+    md_content = jupytext.jupytext.read(notebook)
+
+    # get lexer: see https://github.com/mwouts/jupytext/issues/993
+    parser = MarkdownIt("commonmark").disable("inline", True)
+    parsed = parser.parse(content)
+    lexer = None
+    for token in parsed:
+        if token.type == "fence" and token.info.startswith("{code-cell}"):
+            lexer = remove_prefix(parser.parse(content)[4].info, "{code-cell}").strip()
+            md_content["metadata"]["language_info"] = {"pygments_lexer": lexer}
+            break
+
+    for cell in md_content["cells"]:
+        cell["source"] = cell["source"].splitlines(keepends=True)
+    if "format_name" in md_content.get("metadata", {}).get("jupytext", {}).get(
+        "text_representation", {}
+    ):
+        return md_content, True
+    return None, None

nbqa/replace_source.py

@@ -10,7 +10,7 @@
 import sys
 from difflib import unified_diff
 from shutil import move
-from typing import Any, Iterator, List, Mapping, MutableMapping, Sequence, Set
+from typing import Any, Dict, Iterator, List, Mapping, MutableMapping, Sequence, Set
 
 import tokenize_rt
 
@@ -172,7 +172,21 @@ def _notebook_cells(
             yield cell
 
 
-def _write_notebook(temp_notebook, trailing_newline, notebook_json):
+def _write_notebook(
+    temp_notebook: str, trailing_newline: bool, notebook_json: Dict[str, Any]
+) -> None:
+    """
+    Write notebook to disc.
+
+    Parameters
+    ----------
+    temp_notebook
+        Location of temporary notebook
+    trailing_newline
+        Whether notebook originally had trailing newline
+    notebook_json
+        New source for notebook.
+    """
     _, ext = os.path.splitext(temp_notebook)
     if ext == ".ipynb":
         with open(temp_notebook, "w", encoding="utf-8") as handle:
@@ -185,7 +199,7 @@ def _write_notebook(temp_notebook, trailing_newline, notebook_json):
                     f"{json.dumps(notebook_json, indent=1, ensure_ascii=False)}"
                 )
     elif ext == ".md":
-        import jupytext
+        import jupytext  # pylint: disable=import-outside-toplevel
 
         for cell in notebook_json["cells"]:
             cell["source"] = "".join(cell["source"])
@@ -213,6 +227,9 @@ def mutate(
         Whether mutation actually happened.
     """
     notebook_json, trailing_newline = read_notebook(notebook)
+    assert notebook_json is not None  # if we got here, it was a valid notebook
+    assert trailing_newline is not None
+
     original_notebook_json = copy.deepcopy(notebook_json)
 
     cells_to_remove = []
@@ -302,6 +319,7 @@ def diff(
         Whether non-null diff was produced.
     """
     notebook_json, _ = read_notebook(notebook)
+    assert notebook_json is not None  # if we got here, it was a valid notebook
 
     cells = _get_cells(python_file, len(notebook_info.temporary_lines), md=md)
 

requirements-dev.txt

@@ -5,12 +5,14 @@ blacken-docs
 coverage[toml]
 flake8
 isort>=5.4.2
+jupytext
 mdformat
 mypy
 pre-commit-hooks
 pydocstyle
 pylint
 pytest
+pytest-cov
 pytest-randomly
 pyupgrade
 yapf

tests/test_non_python_notebook.py

@@ -24,7 +24,8 @@ def test_non_python_notebook(capsys: "CaptureFixture") -> None:
         "No valid notebooks found in given path(s)\n"
         "\n"
         "\x1b[1m\n"
-        "If you believe the notebook(s) to be valid, please report a bug at https://github.com/nbQA-dev/nbQA/issues \x1b[0m\n"
+        "If you believe the notebook(s) to be valid, please report a bug "
+        "at https://github.com/nbQA-dev/nbQA/issues \x1b[0m\n"
         "\n"
     )
     assert err == expected_err

tests/test_runtime_errors.py

@@ -235,14 +235,7 @@ def test_directory_without_notebooks(capsys: "CaptureFixture") -> None:
     capsys
         Pytest fixture to capture stdout and stderr.
     """
-    main(["black", "docs"])
+    main(["black", "LICENSES"])
     _, err = capsys.readouterr()
-    expected_err = (
-        'No valid notebooks found in given path(s)\n'
-        '\n'
-        '\x1b[1m\n'
-        'If you believe the notebook(s) to be valid, please report a bug at '
-        'https://github.com/nbQA-dev/nbQA/issues \x1b[0m\n'
-        '\n'
-    )
+    expected_err = "No notebooks found in given path(s)\n"
     assert err == expected_err