feat: better differences for multiline strings

Author: MaksimMisin

pytest_icdiff.py

@@ -56,6 +56,12 @@ def pytest_addoption(parser):
         action="store_true",
         help="pytest-icdiff:  strip any trailing carriage return at the end of an input line",
     )
+    parser.addoption(
+        "--icdiff-multiline-string",
+        default=False,
+        action="store_true",
+        help="pytest-icdiff:  proper differences for multiline strings",
+    )
 
 
 def pytest_assertrepr_compare(config, op, left, right):
@@ -76,8 +82,16 @@ def pytest_assertrepr_compare(config, op, left, right):
     half_cols = COLS / 2 - MARGINS
     TABSIZE = int(config.getoption("--icdiff-tabsize") or 2)
 
-    pretty_left = pformat(left, indent=TABSIZE, width=half_cols).splitlines()
-    pretty_right = pformat(right, indent=TABSIZE, width=half_cols).splitlines()
+    if (
+        config.getoption("--icdiff-multiline-string")
+        and isinstance(left, str)
+        and isinstance(right, str)
+    ):
+        pretty_left = left.splitlines()
+        pretty_right = right.splitlines()
+    else:
+        pretty_left = pformat(left, indent=TABSIZE, width=half_cols).splitlines()
+        pretty_right = pformat(right, indent=TABSIZE, width=half_cols).splitlines()
     diff_cols = COLS - MARGINS
 
     if len(pretty_left) < 3 or len(pretty_right) < 3: