luci-app-https-dns-proxy: fix get_providers() invalid JSON in directory fallback

[unglazed7010]

Fixes #8647

Summary

• get_providers() emitted a trailing comma after every provider file in the directory-scan fallback, producing JSON rejected by strict parsers and silently breaking the provider list in the UI
• An empty $providersDir caused cat to fail on a literal glob string while still emitting ,, producing [,]

Patch

root/usr/libexec/rpcd/luci.https-dns-proxy

• Flip comma placement: emit separator before each item after the first (not after every item)
• Add [ -f "$f" ] || continue guard and narrow glob to *.json so an empty/absent directory yields a valid empty array instead of broken output
• Allow _LUCI_PROVIDERS_DIR / _LUCI_PROVIDERS_JSON env-var overrides (default unchanged) to make the fallback path exercisable in the test harness without touching live system paths

tests/run_tests.sh

New section 04 — three tests:

1. Directory fallback output is valid JSON (python3 json parser accepts it)
2. All 45 providers are present in the output (count check)
3. Empty providers directory yields a valid empty array

Test run results

## 04: getProviders JSON output

  PASS: getProviders dir-fallback returns valid JSON
  PASS: getProviders dir-fallback: all 45 providers present
  PASS: getProviders empty dir-fallback: valid empty array

Ran 335 tests, 335 passed, 0 failed

(was 332 tests before this patch; all pre-existing tests still pass)

Signed-off-by: unglazed7010 thatblueghoul@gmail.com

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  $\textsf{luci-app-https-dns-proxy: fix get_providers() invalid JSON i\color{yellow}{n directory fallback}\color{red}{}}$

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[egc112]

Please direct your PR upstream to:
https://github.com/mossdef-org/luci-app-https-dns-proxy

Thanks for your contribution

[openwrt-ai]

Reviewed 1 new commit. This PR modifies luci-app-https-dns-proxy, which is maintained out-of-tree at https://github.com/mossdef-org/luci-app-https-dns-proxy and should be submitted there rather than reviewed/merged in openwrt/luci. See the inline comment for details; the underlying fix appears sound but belongs upstream.

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Generated by Claude Code

[openwrt-ai]

luci-app-https-dns-proxy is maintained out-of-tree, not in openwrt/luci. Changes to this RPC backend (and the accompanying tests) should be submitted to the upstream repository so they don't get overwritten on the next sync: https://github.com/mossdef-org/luci-app-https-dns-proxy

The fix itself looks reasonable (the trailing-comma / [,] bug is real), but it needs to land upstream rather than here. Please redirect this PR there.

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Generated by Claude Code