ruby-grape / grape / 33497701357

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master: 97%

Pull #2880

github

Skip the version pattern test when it is the one that matches anything

`Versioner::Path#version_from_first_segment` runs on every request of a
path-versioned API, and tested the candidate segment against `pattern`:

    return unless potential_version.match?(pattern)

`pattern` defaults to `/.*/i`, which matches any segment including the empty
one, so for that value the test can only ever say yes. It is also what every
API that declares a version the usual way is holding: `Endpoint#build_stack`
does not pass `pattern:` when it builds the versioner, and the DSL rejects the
keyword outright:

    version 'v1', using: :path, pattern: /v.+/
    # => ArgumentError: unknown keyword: :pattern

A pattern does reach the middleware when an API inserts the versioner itself,
which the `use` DSL supports:

    use Grape::Middleware::Versioner::Path, versions: %w[v1], pattern: /v.+/

That keeps working unchanged — under `/v.+/` a `/x1/...` segment is not taken
as a version, where the default takes it. Only the default is skipped.

Name the default and hold the pattern only when an API supplied something else,
so the regexp runs when it can decide something and not otherwise. `pattern`
still answers the default, and a supplied pattern is still enforced — both
branches stay covered by the existing specs, which construct the middleware
with `pattern: /v./i` and assert on a segment that matches and one that does
not.

What it buys, measured in one process on the segment the versioner tests:

    seg.match?(/.*/i)                      57 ns
    custom_pattern && !seg.match?(...)     18 ns   (nil, so short-circuits)

That is roughly 39 ns per request of a path-versioned API — about 0.7% of a
minimal request, and nothing at all for an API with no version. End to end it
sits below what the version_throughput harness can resolve (+0.4% median of 9
interleaved runs, against a noise floor of several percent), so no end-to-end
figure is claimed here. Allocation counts are unc... (continued)

1238 of 1332 branches covered (92.94%)

Branch coverage included in aggregate %.

3912 of 3980 relevant lines covered (98.29%)

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