Ensure no double newlines in files generated by "mix new" - #15711
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josevalim merged 2 commits intoAug 3, 2026
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Add assertions to Mix.Tasks.NewTest to refute consecutive empty lines
("\n\n\n") in generated README.md and .gitignore files for both standard
and umbrella projects, preventing accidental regression of template formatting
issues (such as fixed in 7a7d7d9).
Replicate the approach from phoenixframework/phoenix#6781, since clearly the Phoenix installer and `mix new` share the `assert_file/1` and `assert_file/2` helpers. All generated files are candidates for these two rules: 1. Every file must end with a single trailing newline. 2. No file may contain consecutive blank lines. Instead of updating lots of tests (which would cause a lot of churn and be a future maintenance burden, easy to miss in new tests), update the helpers to enforce these rules on every file. Exceptions can be easily added in the future if needed.
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When working on a related PR for Phoenix, I realized we could do better and update the Sent as a separate commit to keep it easy to revert/drop. |
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💚 💙 💜 💛 ❤️ |
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Add assertions to Mix.Tasks.NewTest to refute consecutive empty lines ("\n\n\n") in generated README.md and .gitignore files for both standard and umbrella projects, preventing accidental regression of template formatting issues (such as fixed in 7a7d7d9).