Updates tsp-openapi3 to emit main.tsp even when formatter fails (#3794)

This updates the `tsp-openapi3` CLI so that it emits `main.tsp` even
when the formatter detects an issue. The CLI will still throw the error
after it is done emitting the file.

The `convertOpenAPI3Document` function used by the website does not
throw on formatter errors - the playground will highlight any TSP errors
already.

Playground example with bad emission:

![image](https://github.com/microsoft/typespec/assets/14189820/cbddf049-5928-4969-b1fa-cbf98ea95bc0)

---------

Co-authored-by: Christopher Radek <Christopher.Radek@microsoft.com>

Author: chrisradek

.chronus/changes/tsp-openapi3-emit-on-bad-format-2024-6-9-16-12-22.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/openapi3"
+---
+
+Updates tsp-openapi3 to always emit main.tsp when formatting encounters an error.

packages/openapi3/src/cli/actions/convert/convert-file.ts

@@ -1,5 +1,5 @@
 import oaParser from "@readme/openapi-parser";
-import { resolvePath } from "@typespec/compiler";
+import { formatTypeSpec, resolvePath } from "@typespec/compiler";
 import { OpenAPI3Document } from "../../../types.js";
 import { CliHost } from "../../types.js";
 import { handleInternalCompilerError } from "../../utils.js";
@@ -14,15 +14,30 @@ export async function convertAction(host: CliHost, args: ConvertCliArgs) {
   const program = transform(model);
   let mainTsp: string;
   try {
-    mainTsp = await generateMain(program);
+    mainTsp = generateMain(program);
   } catch (err) {
     handleInternalCompilerError(err);
   }
 
+  let formatError;
+  // attempt to format the TSP and track if it threw an error
+  try {
+    mainTsp = await formatTypeSpec(mainTsp, {
+      printWidth: 100,
+      tabWidth: 2,
+    });
+  } catch (err) {
+    formatError = err;
+  }
+
   if (args["output-dir"]) {
     await host.mkdirp(args["output-dir"]);
     await host.writeFile(resolvePath(args["output-dir"], "main.tsp"), mainTsp);
   }
+
+  if (formatError) {
+    handleInternalCompilerError(formatError);
+  }
 }
 
 function parseOpenApiFile(path: string): Promise<OpenAPI3Document> {

packages/openapi3/src/cli/actions/convert/convert.ts

@@ -1,8 +1,17 @@
+import { formatTypeSpec } from "@typespec/compiler";
 import { OpenAPI3Document } from "../../../types.js";
 import { generateMain } from "./generators/generate-main.js";
 import { transform } from "./transforms/transforms.js";
 
 export async function convertOpenAPI3Document(document: OpenAPI3Document) {
   const program = transform(document);
-  return await generateMain(program);
+  const content = generateMain(program);
+  try {
+    return await formatTypeSpec(content, {
+      printWidth: 100,
+      tabWidth: 2,
+    });
+  } catch {
+    return content;
+  }
 }

packages/openapi3/src/cli/actions/convert/generators/generate-main.ts

@@ -1,11 +1,10 @@
-import { formatTypeSpec } from "@typespec/compiler";
 import { TypeSpecProgram } from "../interfaces.js";
 import { generateModel } from "./generate-model.js";
 import { generateOperation } from "./generate-operation.js";
 import { generateServiceInformation } from "./generate-service-info.js";
 
-export async function generateMain(program: TypeSpecProgram): Promise<string> {
-  const content = `
+export function generateMain(program: TypeSpecProgram): string {
+  return `
   import "@typespec/http";
   import "@typespec/openapi";
   import "@typespec/openapi3";
@@ -19,9 +18,4 @@ export async function generateMain(program: TypeSpecProgram): Promise<string> {
 
   ${program.operations.map(generateOperation).join("\n\n")}
   `;
-
-  return formatTypeSpec(content, {
-    printWidth: 100,
-    tabWidth: 2,
-  });
 }

packages/openapi3/test/tsp-openapi3/convert-openapi3-doc.test.ts

@@ -0,0 +1,47 @@
+import { formatTypeSpec } from "@typespec/compiler";
+import { strictEqual } from "node:assert";
+import { it } from "vitest";
+import { convertOpenAPI3Document } from "../../src/index.js";
+
+it("should convert an OpenAPI3 document to a formatted TypeSpec program", async () => {
+  const tsp = await convertOpenAPI3Document({
+    info: {
+      title: "Test Service",
+      version: "1.0.0",
+    },
+    openapi: "3.0.0",
+    paths: {},
+    components: {
+      schemas: {
+        Foo: {
+          type: "string",
+        },
+      },
+    },
+  });
+
+  strictEqual(
+    tsp,
+    await formatTypeSpec(
+      `
+      import "@typespec/http";
+      import "@typespec/openapi";
+      import "@typespec/openapi3";
+
+      using Http;
+      using OpenAPI;
+
+      @service({
+        title: "Test Service",
+      })
+      @info({
+        version: "1.0.0",
+      })
+      namespace TestService;
+
+      scalar Foo extends string;
+        `,
+      { printWidth: 100, tabWidth: 2 }
+    )
+  );
+});