Move diff utils to beets/util/diff.py

beets/ui/__init__.py

@@ -28,7 +28,6 @@ import sqlite3
 import sys
 import textwrap
 import traceback
-from difflib import SequenceMatcher
 from functools import cache
 from typing import TYPE_CHECKING, Any
 
@@ -47,13 +46,12 @@ from beets.util.color import (
     uncolorize,
 )
 from beets.util.deprecation import deprecate_for_maintainers
+from beets.util.diff import _field_diff
 from beets.util.functemplate import template
 
 if TYPE_CHECKING:
     from collections.abc import Callable, Iterable
 
-    from beets.dbcore.db import FormattedMapping
-
 
 # On Windows platforms, use colorama to support "ANSI" terminal colors.
 if sys.platform == "win32":
@@ -444,25 +442,6 @@ def input_select_objects(prompt, objs, rep, prompt_all=None):
         return []
 
 
-def colordiff(a: str, b: str) -> tuple[str, str]:
-    """Intelligently highlight the differences between two strings."""
-    before = ""
-    after = ""
-
-    matcher = SequenceMatcher(lambda _: False, a, b)
-    for op, a_start, a_end, b_start, b_end in matcher.get_opcodes():
-        before_part, after_part = a[a_start:a_end], b[b_start:b_end]
-        if op in {"delete", "replace"}:
-            before_part = colorize("text_diff_removed", before_part)
-        if op in {"insert", "replace"}:
-            after_part = colorize("text_diff_added", after_part)
-
-        before += before_part
-        after += after_part
-
-    return before, after
-
-
 def get_path_formats(subview=None):
     """Get the configuration's path formats as a list of query/template
     pairs.
@@ -816,59 +795,6 @@ def print_newline_layout(
                 print_(f"{indent_str * 2}{line}")
 
 
-FLOAT_EPSILON = 0.01
-
-
-def _multi_value_diff(field: str, oldset: set[str], newset: set[str]) -> str:
-    added = newset - oldset
-    removed = oldset - newset
-
-    parts = [
-        f"{field}:",
-        *(colorize("text_diff_removed", f"  - {i}") for i in sorted(removed)),
-        *(colorize("text_diff_added", f"  + {i}") for i in sorted(added)),
-    ]
-    return "\n".join(parts)
-
-
-def _field_diff(
-    field: str, old: FormattedMapping, new: FormattedMapping
-) -> str | None:
-    """Given two Model objects and their formatted views, format their values
-    for `field` and highlight changes among them. Return a human-readable
-    string. If the value has not changed, return None instead.
-    """
-    # If no change, abort.
-    if (oldval := old.model.get(field)) == (newval := new.model.get(field)) or (
-        isinstance(oldval, float)
-        and isinstance(newval, float)
-        and abs(oldval - newval) < FLOAT_EPSILON
-    ):
-        return None
-
-    if isinstance(oldval, list):
-        if (oldset := set(oldval)) != (newset := set(newval)):
-            return _multi_value_diff(field, oldset, newset)
-        return None
-
-    # Get formatted values for output.
-    oldstr, newstr = old.get(field, ""), new.get(field, "")
-    if field not in new:
-        return colorize("text_diff_removed", f"{field}: {oldstr}")
-
-    if field not in old:
-        return colorize("text_diff_added", f"{field}: {newstr}")
-
-    # For strings, highlight changes. For others, colorize the whole thing.
-    if isinstance(oldval, str):
-        oldstr, newstr = colordiff(oldstr, newstr)
-    else:
-        oldstr = colorize("text_diff_removed", oldstr)
-        newstr = colorize("text_diff_added", newstr)
-
-    return f"{field}: {oldstr} -> {newstr}"
-
-
 def show_model_changes(
     new: library.LibModel,
     old: library.LibModel | None = None,

beets/util/diff.py

@@ -0,0 +1,81 @@
+from __future__ import annotations
+
+from difflib import SequenceMatcher
+from typing import TYPE_CHECKING
+
+from .color import colorize
+
+if TYPE_CHECKING:
+    from beets.dbcore.db import FormattedMapping
+
+
+def colordiff(a: str, b: str) -> tuple[str, str]:
+    """Intelligently highlight the differences between two strings."""
+    before = ""
+    after = ""
+
+    matcher = SequenceMatcher(lambda _: False, a, b)
+    for op, a_start, a_end, b_start, b_end in matcher.get_opcodes():
+        before_part, after_part = a[a_start:a_end], b[b_start:b_end]
+        if op in {"delete", "replace"}:
+            before_part = colorize("text_diff_removed", before_part)
+        if op in {"insert", "replace"}:
+            after_part = colorize("text_diff_added", after_part)
+
+        before += before_part
+        after += after_part
+
+    return before, after
+
+
+FLOAT_EPSILON = 0.01
+
+
+def _multi_value_diff(field: str, oldset: set[str], newset: set[str]) -> str:
+    added = newset - oldset
+    removed = oldset - newset
+
+    parts = [
+        f"{field}:",
+        *(colorize("text_diff_removed", f"  - {i}") for i in sorted(removed)),
+        *(colorize("text_diff_added", f"  + {i}") for i in sorted(added)),
+    ]
+    return "\n".join(parts)
+
+
+def _field_diff(
+    field: str, old: FormattedMapping, new: FormattedMapping
+) -> str | None:
+    """Given two Model objects and their formatted views, format their values
+    for `field` and highlight changes among them. Return a human-readable
+    string. If the value has not changed, return None instead.
+    """
+    # If no change, abort.
+    if (oldval := old.model.get(field)) == (newval := new.model.get(field)) or (
+        isinstance(oldval, float)
+        and isinstance(newval, float)
+        and abs(oldval - newval) < FLOAT_EPSILON
+    ):
+        return None
+
+    if isinstance(oldval, list):
+        if (oldset := set(oldval)) != (newset := set(newval)):
+            return _multi_value_diff(field, oldset, newset)
+        return None
+
+    # Get formatted values for output.
+    oldstr, newstr = old.get(field, ""), new.get(field, "")
+    if field not in new:
+        return colorize("text_diff_removed", f"{field}: {oldstr}")
+
+    if field not in old:
+        return colorize("text_diff_added", f"{field}: {newstr}")
+
+    # For strings, highlight changes. For others, colorize the whole thing.
+    if isinstance(oldval, str):
+        oldstr, newstr = colordiff(oldstr, newstr)
+    else:
+        oldstr = colorize("text_diff_removed", oldstr)
+        newstr = colorize("text_diff_added", newstr)
+
+    return f"{field}: {oldstr} -> {newstr}"

pyproject.toml

@@ -329,7 +329,7 @@ ignore = [
 "beets/**" = ["PT"]
 "test/plugins/test_ftintitle.py" = ["E501"]
 "test/test_util.py" = ["E501"]
-"test/ui/test_field_diff.py" = ["E501"]
+"test/util/test_diff.py" = ["E501"]
 "test/util/test_id_extractors.py" = ["E501"]
 "test/**" = ["RUF001"] # we use Unicode characters in tests