chore: migrate to vitest

[JP-Ellis]

Replace mocha with vitest for faster test running, and native TS support. Also reduce the number of dependencies by switching to vitest's own assertion library.

[JP-Ellis]

PS: Aware of the CI failure, will follow up (just getting it out first for visibility)

[Copilot]

Pull request overview

This PR migrates the project’s test runner from Mocha/Chai/Sinon + NYC to Vitest, aiming for faster test execution, simpler dependencies, and built-in coverage via V8.

Changes:

• Add Vitest configuration (globals, timeouts, coverage settings) and switch npm test / npm run coverage to Vitest.
• Update unit/integration tests to use Vitest/Jest-style matchers and vi mocks instead of Chai/Sinon.
• Remove Mocha/NYC configuration files and update some regression/example package lockfiles accordingly.

Reviewed changes

Copilot reviewed 32 out of 44 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
vitest.config.ts	Introduces Vitest runner + coverage configuration.
src/xml/xmlElement.spec.ts	Replaces Chai assertions with Vitest matchers.
src/v4/http/responseWithPluginBuilder.spec.ts	Replaces Sinon stubs with vi.fn() and Vitest mock assertions.
src/v4/http/responseBuilder.spec.ts	Migrates builder tests to vi mocks + Vitest assertions.
src/v4/http/requestWithPluginBuilder.spec.ts	Migrates request plugin builder tests to Vitest.
src/v4/http/requestBuilder.spec.ts	Migrates request builder tests to Vitest.
src/v4/http/index.spec.ts	Migrates V4 HTTP executeTest specs; switches stubs to vi.fn().
src/v3/pact.spec.ts	Migrates PactV3 executeTest specs to Vitest mocks/assertions.
src/v3/matchers.spec.ts	Migrates matcher specs to Vitest toEqual/toThrow assertions.
src/v3/ffi.spec.ts	Migrates FFI spec assertions to Vitest matchers.
src/pact.integration.spec.ts	Migrates integration spec assertions away from Chai.
src/messageProviderPact.spec.ts	Migrates MessageProvider tests from chai-as-promised to async/await + Vitest assertions.
src/messageConsumerPact.spec.ts	Migrates MessageConsumer tests to async/await + Vitest assertions.
src/httpPact/index.spec.ts	Migrates HTTP Pact tests to Vitest and vi.fn() call assertions.
src/httpPact/ffi.spec.ts	Migrates HTTP FFI tests to Vitest and vi.fn() call assertions.
src/dsl/verifier/verifier.spec.ts	Replaces proxyquire/sinon with vi.mock and vi.spyOn patterns.
src/dsl/verifier/proxy/stateHandler/stateHandler.spec.ts	Migrates state handler proxy tests to Vitest spies/assertions.
src/dsl/verifier/proxy/stateHandler/setupStates.spec.ts	Migrates setupStates tests to Vitest spies/assertions.
src/dsl/verifier/proxy/proxyRequest.spec.ts	Migrates proxy request tests to Vitest matchers.
src/dsl/verifier/proxy/proxy.spec.ts	Migrates waitForServerReady tests to async/await + Vitest assertions.
src/dsl/verifier/proxy/parseBody.spec.ts	Migrates parseBody tests to Vitest matchers.
src/dsl/verifier/proxy/hooks.spec.ts	Migrates hook tests from sinon stubs to vi.fn() and Vitest assertions.
src/dsl/matchers.spec.ts	Migrates DSL matcher tests from Chai to Vitest matchers.
src/dsl/interaction.spec.ts	Migrates interaction tests to Vitest matchers and removes chai-as-promised.
src/dsl/graphql.spec.ts	Migrates GraphQL interaction tests to Vitest assertions.
src/dsl/apolloGraphql.spec.ts	Migrates Apollo GraphQL interaction tests to Vitest assertions.
src/common/request.spec.ts	Migrates request tests to async/await and Vitest assertions.
src/common/net.spec.ts	Migrates network/port availability tests to async/await and Vitest assertions.
package.json	Switches scripts/deps from Mocha/NYC to Vitest + V8 coverage.
regression/v2/serverless/package.json	Updates the local file dependency path for @pact-foundation/pact.
regression/v2/serverless/package-lock.json	Lockfile updates reflecting dependency + toolchain changes.
examples/messages/package-lock.json	Lockfile updates reflecting Vitest toolchain changes.
.nycrc	Removes NYC configuration (coverage handled by Vitest).
.mocharc.json	Removes Mocha configuration (runner replaced by Vitest).

Files not reviewed (1)

• regression/v2/serverless/package-lock.json: Language not supported

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 86.31579% with 13 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (master@68155a7). Learn more about missing BASE report.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/index.ts	0.00%	13 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #1789   +/-   ##
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  Coverage          ?   60.60%           
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  Files             ?       67           
  Lines             ?     4132           
  Branches          ?      350           
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  Hits              ?     2504           
  Misses            ?     1626           
  Partials          ?        2           

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