Format ourselves in preview mode (#2889)

diff --git a/pyproject.toml b/pyproject.toml
index ec617790039bf290b644b58e00cff9bf78e43f3b..d9373740a5c4d1cc30d8cfd348eff243ab7ac568 100644 (file)
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,7 +17,10 @@ extend-exclude = '''
   | profiling
 )/
 '''
-
+# We use preview style for formatting Black itself. If you
+# want stable formatting across releases, you should keep
+# this off.
+preview = true
 
 # Build system information below.
 # NOTE: You don't need this in your own Black configuration.

diff --git a/src/black/__init__.py b/src/black/__init__.py
index b7bf822ed089456cc756d474374ea8f5449eec95..c1b989536a72aa89e54da876aeda35fdbfc0d623 100644 (file)
--- a/src/black/__init__.py
+++ b/src/black/__init__.py
@@ -1358,10 +1358,10 @@ def assert_equivalent(src: str, dst: str) -> None:
         src_ast = parse_ast(src)
     except Exception as exc:
         raise AssertionError(
-            f"cannot use --safe with this file; failed to parse source file AST: "
+            "cannot use --safe with this file; failed to parse source file AST: "
             f"{exc}\n"
-            f"This could be caused by running Black with an older Python version "
-            f"that does not support new syntax used in your source file."
+            "This could be caused by running Black with an older Python version "
+            "that does not support new syntax used in your source file."
         ) from exc
 
     try:
@@ -1380,7 +1380,7 @@ def assert_equivalent(src: str, dst: str) -> None:
         log = dump_to_file(diff(src_ast_str, dst_ast_str, "src", "dst"))
         raise AssertionError(
             "INTERNAL ERROR: Black produced code that is not equivalent to the"
-            f" source.  Please report a bug on "
+            " source.  Please report a bug on "
             f"https://github.com/psf/black/issues.  This diff might be helpful: {log}"
         ) from None
 

diff --git a/tests/test_ipynb.py b/tests/test_ipynb.py
index 473047a3b32d63f1ddd80ce9b2b277b09221af60..b534d77c22abea804c38532583cd230fec218197 100644 (file)
--- a/tests/test_ipynb.py
+++ b/tests/test_ipynb.py
@@ -415,7 +415,7 @@ def test_ipynb_diff_with_change() -> None:
             f"--config={EMPTY_CONFIG}",
         ],
     )
-    expected = "@@ -1,3 +1,3 @@\n %%time\n \n-print('foo')\n" '+print("foo")\n'
+    expected = "@@ -1,3 +1,3 @@\n %%time\n \n-print('foo')\n+print(\"foo\")\n"
     assert expected in result.output
 
 
@@ -494,7 +494,7 @@ def test_ipynb_flag(tmp_path: pathlib.Path) -> None:
             f"--config={EMPTY_CONFIG}",
         ],
     )
-    expected = "@@ -1,3 +1,3 @@\n %%time\n \n-print('foo')\n" '+print("foo")\n'
+    expected = "@@ -1,3 +1,3 @@\n %%time\n \n-print('foo')\n+print(\"foo\")\n"
     assert expected in result.output