fix: allow tests to be run from (hopefully) any directory (GH-2574)

[etc/vim.git] / src / black / output.py

diff --git a/src/black/output.py b/src/black/output.py
index 6831524090d9a82107146bf8a89ee815fa58d1c9..fd3dbb376279497c2fc23f6eb7f03d6db96c4fc7 100644 (file)
--- a/src/black/output.py
+++ b/src/black/output.py
@@ -3,6 +3,7 @@
 The double calls are for patching purposes in tests.
 """
 
+import json
 from typing import Any, Optional
 from mypy_extensions import mypyc_attr
 import tempfile
@@ -34,6 +35,23 @@ def err(message: Optional[str] = None, nl: bool = True, **styles: Any) -> None:
     _err(message, nl=nl, **styles)
 
 
+def ipynb_diff(a: str, b: str, a_name: str, b_name: str) -> str:
+    """Return a unified diff string between each cell in notebooks `a` and `b`."""
+    a_nb = json.loads(a)
+    b_nb = json.loads(b)
+    diff_lines = [
+        diff(
+            "".join(a_nb["cells"][cell_number]["source"]) + "\n",
+            "".join(b_nb["cells"][cell_number]["source"]) + "\n",
+            f"{a_name}:cell_{cell_number}",
+            f"{b_name}:cell_{cell_number}",
+        )
+        for cell_number, cell in enumerate(a_nb["cells"])
+        if cell["cell_type"] == "code"
+    ]
+    return "".join(diff_lines)
+
+
 def diff(a: str, b: str, a_name: str, b_name: str) -> str:
     """Return a unified diff string between strings `a` and `b`."""
     import difflib
@@ -45,7 +63,8 @@ def diff(a: str, b: str, a_name: str, b_name: str) -> str:
         a_lines, b_lines, fromfile=a_name, tofile=b_name, n=5
     ):
         # Work around https://bugs.python.org/issue2142
-        # See https://www.gnu.org/software/diffutils/manual/html_node/Incomplete-Lines.html
+        # See:
+        # https://www.gnu.org/software/diffutils/manual/html_node/Incomplete-Lines.html
         if line[-1] == "\n":
             diff_lines.append(line)
         else: