Fix incorrect ETag values

[martincostello]

Fix incorrect ETag for compressed files by resetting the compressed stream to the beginning before computing the SHA256 hash.

See #3486 (comment).

[Copilot]

Pull Request Overview

This PR ensures the compressed stream is reset before computing the hash so that ETag values for compressed files are correct.

• Reset the compressed stream position in EmbeddedResourceProvider before hashing.
• Introduce a shared constant for the empty-string hash in tests and replace hard-coded literals.
• Add assertions to verify the empty-string hash does not appear in the ETag tag.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
test/Swashbuckle.AspNetCore.IntegrationTests/SwaggerUIIntegrationTests.cs	Added EmptyStringSha256Hash constant, replaced literals, and added Assert.DoesNotContain checks on ETag.
test/Swashbuckle.AspNetCore.IntegrationTests/ReDocIntegrationTests.cs	Mirrored the same constant and assertions changes for ReDoc tests.
src/Shared/EmbeddedResourceProvider.cs	Inserted compressed.Seek(0, SeekOrigin.Begin) before hashing.

Comments suppressed due to low confidence (2)

test/Swashbuckle.AspNetCore.IntegrationTests/SwaggerUIIntegrationTests.cs:10

• The constant name suggests SHA256 but the code uses SHA1; consider renaming it to EmptyStringSha1Hash for accuracy.

    private const string EmptyStringSha256Hash = "2jmj7l5rSw0yVb/vlWAYkK/YBwk=";

test/Swashbuckle.AspNetCore.IntegrationTests/ReDocIntegrationTests.cs:13

• The constant name suggests SHA256 but the code uses SHA1; consider renaming it to EmptyStringSha1Hash for accuracy.

    private const string EmptyStringSha256Hash = "2jmj7l5rSw0yVb/vlWAYkK/YBwk=";

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.91%. Comparing base (4903084) to head (e52cc59).
Report is 1 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3490   +/-   ##
=======================================
  Coverage   93.91%   93.91%           
=======================================
  Files         110      110           
  Lines        3810     3811    +1     
  Branches      723      723           
=======================================
+ Hits         3578     3579    +1     
  Misses        232      232           

Flag	Coverage Δ
Linux	93.91% <100.00%> (+<0.01%)	⬆️
Windows	93.91% <100.00%> (+<0.01%)	⬆️
macOS	93.91% <100.00%> (+<0.01%)	⬆️

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