fix: Error on missing prettier config

When a prettier config file is specified but can't be found a default prettier config is silently used as a fallback.
This change causes an error to be raised when the specified prettier config doesn't exist.

Closes #908

Author: duncanbeevers

src/index.ts

@@ -1,5 +1,6 @@
 import type { GlobalContext, OpenAPI2, OpenAPI3, SchemaObject, SwaggerToTSOptions } from "./types.js";
 import path from "path";
+import fs from "fs";
 import prettier from "prettier";
 import parserTypescript from "prettier/parser-typescript.js";
 import { Readable } from "stream";
@@ -115,7 +116,9 @@ async function openapiTS(
   };
   if (options && options.prettierConfig) {
     try {
-      const userOptions = await prettier.resolveConfig(path.resolve(process.cwd(), options.prettierConfig));
+      const prettierConfigFile = path.resolve(process.cwd(), options.prettierConfig);
+      await fs.promises.access(prettierConfigFile, fs.constants.F_OK);
+      const userOptions = await prettier.resolveConfig(prettierConfigFile);
       prettierOptions = {
         ...(userOptions || {}),
         ...prettierOptions,

test/bin/cli.test.js

@@ -20,14 +20,20 @@ describe("cli", () => {
   });
 
   it("--prettier-config (.js)", async () => {
-    execSync(`${cmd} specs/petstore.yaml -o generated/prettier-js.ts --prettier-config fixtures/prettier.config.js`, {
+    execSync(`${cmd} specs/petstore.yaml -o generated/prettier-js.ts --prettier-config fixtures/prettier.config.cjs`, {
       cwd,
     });
     const generated = fs.readFileSync(new URL("./generated/prettier-js.ts", cwd), "utf8");
     const expected = eol.lf(fs.readFileSync(new URL("./expected/prettier-js.ts", cwd), "utf8"));
     expect(generated).to.equal(expected);
   });
 
+  it("--prettier-config (missing)", async () => {
+    expect(() => {
+      execSync(`${cmd} specs/petstore.yaml -o generated/prettier-missing.ts --prettier-config NO_SUCH_FILE`);
+    }).to.throw('NO_SUCH_FILE');
+  });
+
   it("stdout", async () => {
     const generated = execSync(`${cmd} specs/petstore.yaml`, { cwd });
     const expected = eol.lf(fs.readFileSync(new URL("./expected/stdout.ts", cwd), "utf8"));