fix#3038
This PR updates the `@typespec/openapi3` package to support converting
OpenAPI3 specs to TypeSpec.
## Example usage:
1. `npm install @typespec/openapi3`
2. `npx openapi3-to-tsp compile --output-dir ./tsp-output
/path/to/openapi-yaml-or-json`
## What's supported
- Parse OpenAPI3 specs in yml/json formats (via 3rd party package)
- Generates file namespace based on OpenAPI3 service name
- Populates `@info` decorator with OpenAPI3 service info
- Converts `#/components/schemas` into TypeSpec models/scalars.
- Converts `#/components/parameters` into TypeSpec models/model
properties as appropriate.
- Generates a response model for every operation/statusCode/contentType
combination.
- Operation tags
- Generates TypeSpec operations with routes/Http Method decorators
- Generates docs/extension decorators
- Most schema decorators
- Model inheritance via `allOf`
- Discriminators
## What's not supported (yet)
- auth
- deprecated directive
- combining multiple versions of an OpenAPI3-defined service into a
single TypeSpec project
- converting `#/components/requestBodies` and `#/components/responses`
into models - TypeSpec doesn't seem to generate these and I didn't find
examples in the wild where they were defined _and_ actually used so
deprioritized.
- emitting warnings/FIXMEs for unexpected/unsupported scenarios
- Probably a lot more that I'm still discovering
## Notes
When going through the TypeSpec -> OpenAPI3 -> TypeSpec loop, the
generated TypeSpec is going to be larger than the original. The biggest
contribution towards this is because I'm currently generating a model
for every possible response on every operation.
I can definitely pare this down with some simple heuristics that take
into account what default statusCode/contentTypes are, and extract the
referenced body type directly in the operation's return signature. I can
also eliminate the `@get` decorators, `@route("/")` routes, and likely
use some of the response models provided by TypeSpec.Http.
However - if I'm using this tool to convert from OpenAPI3 to TypeSpec -
I thought it might be preferable to be more explicit in the generated
output so there's no mystery on how things actually get defined. Will be
interested in feedback on this.
## Testing
For tests, I generate TypeSpec files for a number of OpenAPI3 specs.
Most of the OpenAPI3 specs I generated from our TypeSpec samples
packages. Then I'm able to compare the generated TypeSpec to the
corresponding original TypeSpec file. I've also been diffing the
OpenAPI3 specs generated from the original and generated TypeSpec files
<- these are what typically show no changes outside of known unsupported
conversions (e.g. auth).
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Co-authored-by: Christopher Radek <Christopher.Radek@microsoft.com>
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