Fix not emitting newline markers in patches#4745
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Liam-DeVoe merged 1 commit intoMay 27, 2026
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`difflib.unified_diff` doesn't emit the marker that git requires when either side of the diff lacks a trailing newline, so `git apply` rejects the resulting patch as corrupt. When both sides' differing last lines lack newlines, the raw output also concatenates the `-` and `+` lines into a single mashed line. Post-process the diff to terminate any no-newline line with `\n` and append the marker.
Liam-DeVoe
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Zac-HD
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May 26, 2026
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Fixes #4744.
Claude-written description
make_patch()inhypothesis/extra/_patching.pyusesdifflib.unified_diff, which doesn't emit the\ No newline at end of filemarker that git requires when either side of the diff lacks a trailing newline. The pytest plugin's resulting patch is therefore rejected bygit applyas corrupt.Worse: when both sides' differing last lines lack newlines, the raw
unified_diffoutput concatenates the-and+lines into a single mashed line (e.g.-last = old+last = new), so the patch isn't just missing an annotation, it's structurally broken.The fix post-processes the diff output: for any line that doesn't end with
\n, terminate it and append the marker. This handles all five permutations (both sides have/lack newline, equal/differing last lines).Two new tests in
tests/patching/test_patching.pyassert exact patch text for the context-line and changed-line cases.