docs: pactfileWriteMode / parallel tests / splitting tests across multiple files

[YOU54F]

We could do with a distinct section on pactfileWriteMode and how to set it in each of the respective languages (if it is available as an option in every language) and circumstances as to why we would need to change it from the default.

Some guidance around running parallel tests and splitting tests (consumer/provider pairs) across multiple test files/specs would be useful as well, which is where this discussion came from

Currently docs exist for

• JS
  • constructor in readme https://docs.pact.io/implementation_guides/javascript/readme#constructor
  • https://docs.pact.io/implementation_guides/javascript/readme#splitting-tests-across-multiple-files
  • https://docs.pact.io/implementation_guides/javascript/readme#parallel-tests
  • changelog https://docs.pact.io/implementation_guides/javascript/changelog#features-38
  • changelog https://docs.pact.io/implementation_guides/javascript/changelog#features-47
• Jest-pact
  • sets to update by default
  • source - https://github.com/pact-foundation/jest-pact/blob/master/src/internal/config.ts#L22
• Go
  • https://docs.pact.io/implementation_guides/go/readme#splitting-tests-across-multiple-files
• Ruby
  • 4 options provided Default value: :overwrite Options: :overwrite, :update, :smart, :none
  • https://docs.pact.io/implementation_guides/ruby/configuration#pactfile_write_mode
• CLI tools - Ruby based (docker/standalone)
  • changelog - https://docs.pact.io/pact_broker/client_cli/changelog#features-60
  • commit - https://github.com/pact-foundation/pact_broker-client/commit/1c039a0

[mefellows]

Thanks Saf!

Interestingly, I saw this issue raised just as I was writing the migration guide for Pact JS. This mode is essentially disappearing in the Rust core, so we should be careful about how we document it.

I think we'll need an approach that works across languages here as we work to replace the Ruby core.