allow exactOptionalPropertyTypes in DT tsconfigs

packages/dtslint/src/checks.ts

@@ -3,8 +3,9 @@ import { TypeScriptVersion } from "@definitelytyped/typescript-versions";
 import assert = require("assert");
 import { pathExists } from "fs-extra";
 import { join as joinPaths } from "path";
+import { CompilerOptions } from "typescript";
 
-import { getCompilerOptions, readJson } from "./util";
+import { readJson } from "./util";
 
 export async function checkPackageJson(dirPath: string, typesVersions: readonly TypeScriptVersion[]): Promise<void> {
   const pkgJsonPath = joinPaths(dirPath, "package.json");
@@ -59,9 +60,7 @@ export interface DefinitelyTypedInfo {
   /** "../" or "../../" or "../../../". This should use '/' even on windows. */
   readonly relativeBaseUrl: string;
 }
-export async function checkTsconfig(dirPath: string, dt: DefinitelyTypedInfo | undefined): Promise<void> {
-  const options = await getCompilerOptions(dirPath);
-
+export function checkTsconfig(options: CompilerOptions, dt: DefinitelyTypedInfo | undefined): void {
   if (dt) {
     const { relativeBaseUrl } = dt;
 
@@ -78,12 +77,11 @@ export async function checkTsconfig(dirPath: string, dt: DefinitelyTypedInfo | u
       const expected = mustHave[key];
       const actual = options[key];
       if (!deepEquals(expected, actual)) {
-        throw new Error(`Expected compilerOptions[${JSON.stringify(key)}] === ${JSON.stringify(expected)}`);
+        throw new Error(`Expected compilerOptions[${JSON.stringify(key)}] === ${JSON.stringify(expected)}, but got ${JSON.stringify(actual)}`);
       }
     }
 
     for (const key in options) {
-      // tslint:disable-line forin
       switch (key) {
         case "lib":
         case "noImplicitAny":
@@ -94,16 +92,14 @@ export async function checkTsconfig(dirPath: string, dt: DefinitelyTypedInfo | u
         case "strictFunctionTypes":
         case "esModuleInterop":
         case "allowSyntheticDefaultImports":
-          // Allow any value
-          break;
-        case "target":
         case "paths":
+        case "target":
         case "jsx":
         case "jsxFactory":
         case "experimentalDecorators":
         case "noUnusedLocals":
         case "noUnusedParameters":
-          // OK. "paths" checked further by types-publisher
+        case "exactOptionalPropertyTypes":
           break;
         default:
           if (!(key in mustHave)) {
@@ -134,6 +130,11 @@ export async function checkTsconfig(dirPath: string, dt: DefinitelyTypedInfo | u
       }
     }
   }
+  if ("exactOptionalPropertyTypes" in options) {
+    if (options.exactOptionalPropertyTypes !== true) {
+      throw new Error('When "exactOptionalPropertyTypes" is present, it must be set to `true`.');
+    }
+  }
 
   if (options.types && options.types.length) {
     throw new Error(

packages/dtslint/src/index.ts

@@ -9,7 +9,7 @@ import { basename, dirname, join as joinPaths, resolve } from "path";
 import { cleanTypeScriptInstalls, installAllTypeScriptVersions, installTypeScriptNext } from "@definitelytyped/utils";
 import { checkPackageJson, checkTsconfig } from "./checks";
 import { checkTslintJson, lint, TsVersion } from "./lint";
-import { mapDefinedAsync, withoutPrefix } from "./util";
+import { getCompilerOptions, mapDefinedAsync, withoutPrefix } from "./util";
 
 async function main(): Promise<void> {
   const args = process.argv.slice(2);
@@ -221,8 +221,8 @@ async function testTypesVersion(
   isLatest: boolean
 ): Promise<void> {
   await checkTslintJson(dirPath, dt);
-  await checkTsconfig(
-    dirPath,
+  checkTsconfig(
+    await getCompilerOptions(dirPath),
     dt ? { relativeBaseUrl: ".." + (isOlderVersion ? "/.." : "") + (isLatest ? "" : "/..") + "/" } : undefined
   );
   const err = await lint(dirPath, lowVersion, hiVersion, isLatest, expectOnly, tsLocal);

packages/dtslint/test/index.test.ts

@@ -2,6 +2,7 @@
 import { join } from "path";
 import { consoleTestResultHandler, runTest } from "tslint/lib/test";
 import { existsSync, readdirSync } from "fs";
+import { checkTsconfig } from "../src/checks";
 
 const testDir = __dirname;
 
@@ -28,15 +29,49 @@ function testSingle(testDirectory: string) {
 }
 
 describe("dtslint", () => {
-  const tests = readdirSync(testDir).filter(x => x !== "index.test.ts");
-  for (const testName of tests) {
-    const testDirectory = join(testDir, testName);
-    if (existsSync(join(testDirectory, "tslint.json"))) {
-      testSingle(testDirectory);
-    } else {
-      for (const subTestName of readdirSync(testDirectory)) {
-        testSingle(join(testDirectory, subTestName));
+  const base = {
+    "module": "commonjs" as any,
+    "lib": [
+      "es6"
+    ],
+    "noImplicitAny": true,
+    "noImplicitThis": true,
+    "strictNullChecks": true,
+    "strictFunctionTypes": true,
+    "baseUrl": "../",
+    "typeRoots": [
+      "../"
+    ],
+    "types": [],
+    "noEmit": true,
+    "forceConsistentCasingInFileNames": true,
+  };
+  describe("checks", () => {
+    it("disallows unknown compiler options", () => {
+      expect(() => checkTsconfig({ ...base, completelyInvented: true }, { relativeBaseUrl: "../" }))
+        .toThrow("Unexpected compiler option completelyInvented");
+    });
+    it("allows exactOptionalPropertyTypes: true", () => {
+      expect(checkTsconfig({ ...base, exactOptionalPropertyTypes: true }, { relativeBaseUrl: "../" }))
+        .toBeFalsy();
+    });
+    it("disallows exactOptionalPropertyTypes: false", () => {
+      expect(() => checkTsconfig({ ...base, exactOptionalPropertyTypes: false }, { relativeBaseUrl: "../" }))
+        .toThrow("When \"exactOptionalPropertyTypes\" is present, it must be set to `true`.");
+    });
+  });
+  describe("rules", () => {
+    const tests = readdirSync(testDir).filter(x => x !== "index.test.ts");
+    for (const testName of tests) {
+      const testDirectory = join(testDir, testName);
+      if (existsSync(join(testDirectory, "tslint.json"))) {
+        testSingle(testDirectory);
+      } else {
+        for (const subTestName of readdirSync(testDirectory)) {
+          testSingle(join(testDirectory, subTestName));
+        }
       }
     }
-  }
+  });
 });
+