Ensure for events containing multiValueHeaders, the Rack::Headers return object is correctly initialised#47
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logandk merged 4 commits intoMay 1, 2026
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- Check that for both 'regular' and `multiValueHeaders` in event parameter, the return responds to lower-cases keys correctly - Check that for multiValueHeaders, the string literal array hash values are concatenated with `\n` separators
The constructor for `Rack::Headers` is inherited from Hash, so using `.new()` just creates a default value for the hash. Set `parse_headers`'s return value to a correctly initialised instance of Rack::Headers.
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Context
My Rack v3 updates unfortunately introduced a regression; when the event from the AWS ALB contains
multiValueHeaders, theparse_headersmethod was essentially setting a default for theRack::Headersinstance it was returning via the.newconstructor. It goes without saying that this isn't what we want!So we want a) test coverage to check that the
parse_headermethod is doing what it should do and b) make sure to correctly initialise theRack::Headersobject whenmultiValueHeadersare present in the event object.Implementation
I've added unit tests for the
parse_headersmethod; I'm happy with the coverage, and I've implement test-driven-development to make sure it caught the aforementioned issue.The actual fix is easy; don't use
.new, and just use the[]operator to create theRack::Headerinstance instead.Patch version bump
I've opted to bump the version to
2.0.1, as I consider this a straight-forward fix with no additional features.