fix: use parsed source text for Prettier formatting #15764
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In Prettier's `parse` function, the input source text is preprocessed using `normalizeInputAndOptions`. This normalizes line endings and therefore affects the AST positions if CLRF was replaced with LF, typically in Windows environments. Consequently, formatting the parsed AST has to use the preprocessed source text in order for the AST positions to align, as otherwise the formatted output is likely to be mangled.
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JoostK
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Aug 2, 2025
| `, | ||
| }); | ||
| writeFiles(DIR, { | ||
| '.prettierrc': '{"endOfLine": "crlf"}', |
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Note that this file cannot exist in the to-match-inline-snapshot-crlf test directory, as it would cause Jest's own usage of Prettier to format everything in the directory to have CRLF line endings, which then get normalized to LF by git and cause Prettier checks to fail, as CRLF is expected. An alternative could be to set up a dedicated .gitattributes file in the folder to instruct Git to use CRLF for this directory wholesale, but I'd rather not check in any CRLF into Git at all.
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Summary
Jest 30 introduced support for Prettier 3+ in #14566, but this may result in mangled source code when run on source files with CRLF line endings. In particular, empty line breaks would get removed, but more complex inputs/snapshots could result in entirely broken code.
The problem occurs due to how
jest-snapshotinvokes Prettier using private APIs in two separate phases: the source text is parsed and formatted using individual API calls and the formatting phase takes the original options, whereas the parsing stage has operated on preprocessed options. Those preprocessed options aren't part of the return value ofparseso cannot be used wholesale when callingformatAST, but the normalized source text is available and can be passed through.Test plan
A new test project has been added which enables CRLF line endings and verifies that the formatted source file with inline snapshot has been formatted correctly. Before this change, the empty newline between the two
expect(...)calls would be removed.