Scrub invalid UTF-8 in FailureFormatter#to_s#403
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`String#encode!(Encoding::UTF_8, invalid: :replace, ...)` is a no-op when the source encoding is already UTF-8. When `body` interpolation produces a UTF-8-tagged string with invalid byte sequences (e.g. binary protobuf bodies surfaced through WebMock failure messages), the existing fix lets those bytes through and `JSON.dump` later crashes in `BuildStatusReporter#write_failure_file` with `Encoding::UndefinedConversionError`, taking down the entire report step. Switch to `force_encoding(Encoding::UTF_8) + scrub!` which handles both the original ASCII-8BIT-source case and the new UTF-8-tagged-with-invalid- bytes case. Adds a regression test for the second case alongside the existing one.
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dersam
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Apr 30, 2026
This was referenced Apr 30, 2026
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Problem
Minitest::Queue::FailureFormatter#to_susesString#encode!(Encoding::UTF_8, invalid: :replace, undef: :replace)to sanitize test output before it gets JSON-serialized inBuildStatusReporter#write_failure_file. Per the Ruby docs,encode!is a no-op when the source and destination encodings are the same. When test output contains a UTF-8-tagged string with invalid byte sequences — common when WebMock surfaces a protobuf request body in an error message — the call silently leaves the bad bytes intact.JSON.dumpthen crashes withEncoding::UndefinedConversionError, and the entireminitest-queue reportstep exits before writing any failure file. Builds with many failures lose every single failure record, breaking flake-triage workflows.Fix
Add
scrub!afterencode!to catch the caseencode!misses.encode!still handles transcoding from non-UTF-8 sources (ASCII-8BIT, ISO-8859-1, etc.), andscrub!cleans any remaining invalid byte sequences in UTF-8-tagged strings. Both use the same default replacement character (U+FFFD).Reference
Original ASCII-8BIT fix: ed4ae26 — this PR closes the remaining gap.
Closes https://github.com/shop/issues/issues/39402
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