make black[jupyter] installation cross-shell (psf#3394)

Author: MarcoGorelli

README.md

@@ -39,7 +39,7 @@ Try it out now using the [Black Playground](https://black.vercel.app). Watch the
 ### Installation
 
 _Black_ can be installed by running `pip install black`. It requires Python 3.7+ to run.
-If you want to format Jupyter Notebooks, install with `pip install 'black[jupyter]'`.
+If you want to format Jupyter Notebooks, install with `pip install "black[jupyter]"`.
 
 If you can't wait for the latest _hotness_ and want to install from GitHub, use:
 

docs/getting_started.md

@@ -17,7 +17,7 @@ Also, you can try out _Black_ online for minimal fuss on the
 ## Installation
 
 _Black_ can be installed by running `pip install black`. It requires Python 3.7+ to run.
-If you want to format Jupyter Notebooks, install with `pip install 'black[jupyter]'`.
+If you want to format Jupyter Notebooks, install with `pip install "black[jupyter]"`.
 
 If you can't wait for the latest _hotness_ and want to install from GitHub, use:
 

src/black/handle_ipynb_magics.py

@@ -64,7 +64,7 @@ def jupyter_dependencies_are_installed(*, verbose: bool, quiet: bool) -> bool:
         if verbose or not quiet:
             msg = (
                 "Skipping .ipynb files as Jupyter dependencies are not installed.\n"
-                "You can fix this by running ``pip install black[jupyter]``"
+                'You can fix this by running ``pip install "black[jupyter]"``'
             )
             out(msg)
         return False

tests/test_no_ipynb.py

@@ -17,7 +17,7 @@ def test_ipynb_diff_with_no_change_single() -> None:
     result = runner.invoke(main, [str(path)])
     expected_output = (
         "Skipping .ipynb files as Jupyter dependencies are not installed.\n"
-        "You can fix this by running ``pip install black[jupyter]``\n"
+        'You can fix this by running ``pip install "black[jupyter]"``\n'
     )
     assert expected_output in result.output
 
@@ -32,6 +32,6 @@ def test_ipynb_diff_with_no_change_dir(tmp_path: pathlib.Path) -> None:
     result = runner.invoke(main, [str(tmp_path)])
     expected_output = (
         "Skipping .ipynb files as Jupyter dependencies are not installed.\n"
-        "You can fix this by running ``pip install black[jupyter]``\n"
+        'You can fix this by running ``pip install "black[jupyter]"``\n'
     )
     assert expected_output in result.output