Typescript generator

[pmcelhaney]

Code to read an openAPI spec and generate TypeScript that Counterfact uses to implement a fake server. The files that export types are meant to stay in sync with the OpenAPI spec. The other files are meant to be used as a starting point for approximating the business logic of the real app.

Here's an example of the code generated for the pet store as of this writing.

/* paths/pets.types.ts */
import type { Pets } from "./../components/Pets.js";
import type { Error } from "./../components/Error.js";
export type HTTP_GET = ({ tools: any }) =>
  | {
      status: 200;
      contentType: "application/json";
      body: Pets;
    }
  | {
      status: number | undefined;
      contentType: "application/json";
      body: Error;
    }
  | { status: 415; contentType: "text/plain"; body: string };
export type HTTP_POST = ({ tools: any }) =>
  | {
      status: 201;
      contentType: "contentType";
      body: null;
    }
  | {
      status: number | undefined;
      contentType: "application/json";
      body: Error;
    }
  | { status: 415; contentType: "text/plain"; body: string };





/* paths/pets/{petId}.ts */
import type { HTTP_GET } from "./{petId}.types.js";
import { PetSchema } from "./../../components/Pet.js";
import { ErrorSchema } from "./../../components/Error.js";
export const GET: HTTP_GET = ({ tools }) => {
  const statusCode = tools.oneOf(["200", "default"]);

  if (statusCode === "200") {
    if (tools.accepts("application/json")) {
      const example = tools.oneOf([]);

      return {
        status: 200,
        contentType: "application/json",
        body: tools.randomFromSchema(PetSchema),
      };
    }
  }
  if (tools.accepts("application/json")) {
    const example = tools.oneOf([]);

    return {
      contentType: "application/json",
      body: tools.randomFromSchema(ErrorSchema),
    };
  }

  return {
    status: 415,
    contentType: "text/plain",
    body: "HTTP 415: Unsupported Media Type",
  };
};





/* components/Error.ts */
export type Error = { code: number; message: string };
export const ErrorSchema = {
  type: "object",
  required: ["code", "message"],
  properties: {
    code: { type: "integer", format: "int32" },
    message: { type: "string" },
  },
};





/* paths/pets/{petId}.types.ts */
import type { Pet } from "./../../components/Pet.js";
import type { Error } from "./../../components/Error.js";
export type HTTP_GET = ({ tools: any }) =>
  | {
      status: 200;
      contentType: "application/json";
      body: Pet;
    }
  | {
      status: number | undefined;
      contentType: "application/json";
      body: Error;
    }
  | { status: 415; contentType: "text/plain"; body: string };





/* components/Pets.ts */
import type { Pet } from "./Pet.js";
import { PetSchema } from "./Pet.js";
export type Pets = Array<Pet>;
export const PetsSchema = {
  type: "array",
  items: PetSchema,
};





/* components/Pet.ts */
export type Pet = { id: number; name: string; tag: string };
export const PetSchema = {
  type: "object",
  required: ["id", "name"],
  properties: {
    id: { type: "integer", format: "int64" },
    name: { type: "string" },
    tag: { type: "string" },
  },
};





/* paths/pets.ts */
import type { HTTP_GET } from "./pets.types.js";
import type { HTTP_POST } from "./pets.types.js";
import { PetsSchema } from "./../components/Pets.js";
import { ErrorSchema } from "./../components/Error.js";
export const GET: HTTP_GET = ({ tools }) => {
  const statusCode = tools.oneOf(["200", "default"]);

  if (statusCode === "200") {
    if (tools.accepts("application/json")) {
      const example = tools.oneOf([]);

      return {
        status: 200,
        contentType: "application/json",
        body: tools.randomFromSchema(PetsSchema),
      };
    }
  }
  if (tools.accepts("application/json")) {
    const example = tools.oneOf([]);

    return {
      contentType: "application/json",
      body: tools.randomFromSchema(ErrorSchema),
    };
  }

  return {
    status: 415,
    contentType: "text/plain",
    body: "HTTP 415: Unsupported Media Type",
  };
};
export const POST: HTTP_POST = ({ tools }) => {
  const statusCode = tools.oneOf(["201", "default"]);

  if (statusCode === "201") {
  }
  if (tools.accepts("application/json")) {
    const example = tools.oneOf([]);

    return {
      contentType: "application/json",
      body: tools.randomFromSchema(ErrorSchema),
    };
  }

  return {
    status: 415,
    contentType: "text/plain",
    body: "HTTP 415: Unsupported Media Type",
  };
};

This branch is way too big. I'm not sure if I'm going to merge it or consider it "one to throw away" and rebuild everything in smaller steps with good testing discipline.

For now, my focus is on getting to a state where I can do a demo in order to (a) prove to myself that this is actually going to work and (b) articulate the vision.