qpc-github / googleapis-api-index-generator

API Index Generator for googleapis

This repository contains the generator for an index file in JSON format for the information in https://github.com/googleapis/googleapis. The index file will itself live in that repository and be regenerated in an automated fashion.

Regenerating the C# code

After modifying the schema, run scripts/generate-schema.sh

Generating the index

• Clone https://github.com/googleapis/googleapis
• Run scripts/generate-index.sh passing in the relative path to the googleapis repo
• The result will be in tmp

Design

The generator is split into two projects:

• Google.Cloud.Tools.ApiIndex.V1: the code generated (by scripts/generate-schema.sh) from the schema protos
• Google.Cloud.Tools.ApiIndexGenerator: the entry point for the generator

The first of these can freely be used by any C# consuming the schema.

The generator is built of model classes (ApiModel, MethodModel etc) which closely correspond to the messages in the schema protos. The intention is that all business logic is performed while creating the models, which can then be transformed straightforwardly in methods conventionally named ToV1Api, ToV1Method etc.

This approach is designed to lend itself to supporting multiple schema versions in the future: the schema dependencies are really all in those ToV1Xyz methods.

Testing

Currently, the simplest way of testing is to run scripts/golden-test.sh. This generates a new index (as tmp/api-index-v1.json) from the protos and YAML files in the test directory, and compares the result with test/golden-index-v1.json.

There are two approaches to testing a change using this "golden" test:

• Work out what the impact should be on the golden index file, edit it accordingly, then implement the change until the test passes.
• Implement the change, run the test (which will fail) and copy the tmp/api-index-v1.json file as the new golden file, then check the diff carefully to ensure that it really is as expected.

The first of these approaches is significantly more diligent and "test-first" than the second... but does take a bit longer. Please do review changes to the golden file carefully!

If we find we need to write genuine unit tests, we can easily add a test project. It's likely that we'd need to also add test protos and a descriptor test generated from them, however - so while changing the "golden" test works, that's probably the simplest approach.