Correctly merge default compiler options

readme.md

@@ -91,6 +91,35 @@ When you have spread your tests over multiple files, you can store all those fil
 
 Now you can put all your test files in the `my-test-dir` directory.
 
+### Custom TypeScript config
+
+By default, `tsd-check` applies the following cofiguration:
+
+```json5
+{
+	"strict": true,
+	"jsx": "React",
+	"target": "ES2017",
+	// following options are set and are not overridable:
+	"moduleResolution": "Node",
+	"skipLibCheck": true
+}
+```
+
+If you wish override these options, you have the possibility to provide a custom TypeScript config to `tsd-check` by specifying it in `package.json`.
+
+*Default options will still apply if you don't override them explicitly.* You can't override the `moduleResolution` and `skipLibCheck` options.
+
+```json
+{
+	"name": "my-module",
+	"tsd-check": {
+		"compilerOptions": {
+			"strict": false
+		}
+	}
+}
+```
 
 ## Assertions
 

source/lib/config.ts

@@ -7,21 +7,17 @@ import {Config} from './interfaces';
  * @param pkg - The package.json object.
  * @returns The config object.
  */
-export default (pkg: any): Config => {
-	const config = {
+export default (pkg: {'tsd-check'?: Partial<Config>}): Config => {
+	const pkgConfig = pkg['tsd-check'] || {};
+
+	return {
 		directory: 'test-d',
+		...pkgConfig,
 		compilerOptions: {
 			strict: true,
 			jsx: JsxEmit.React,
-			target: ScriptTarget.ES2017
-		},
-		...pkg['tsd-check']
-	};
-
-	return {
-		...config,
-		compilerOptions: {
-			...config.compilerOptions,
+			target: ScriptTarget.ES2017,
+			...pkgConfig.compilerOptions,
 			...{
 				moduleResolution: ModuleResolutionKind.NodeJs,
 				skipLibCheck: true

source/test/fixtures/failure-strict-null-checks-as-default-config-value/index.d.ts

@@ -0,0 +1 @@
+export default function (foo: number): number | null;

source/test/fixtures/failure-strict-null-checks-as-default-config-value/index.js

@@ -0,0 +1,3 @@
+module.exports.default = foo => {
+	return foo > 0 ? foo : null;
+};

source/test/fixtures/failure-strict-null-checks-as-default-config-value/index.test-d.ts

@@ -0,0 +1,4 @@
+import {expectType} from '../../..';
+import aboveZero from '.';
+
+expectType<number>(aboveZero(1));

source/test/fixtures/failure-strict-null-checks-as-default-config-value/package.json

@@ -0,0 +1,7 @@
+{
+	"name": "foo",
+	"tsd-check": {
+		"compilerOptions": {
+		}
+	}
+}

source/test/test.ts

@@ -58,20 +58,27 @@ test('fail if `typings` property is used instead of `types`', async t => {
 });
 
 test('fail if tests don\'t pass in strict mode', async t => {
-	const diagnostics = await m({
-		cwd: path.join(__dirname, 'fixtures/failure-strict-null-checks')
-	});
-
-	const {fileName, message, severity, line, column} = diagnostics[0];
-	t.true(/failure-strict-null-checks\/index.test-d.ts$/.test(fileName));
-	t.is(
-		message,
-		`Argument of type 'number | null' is not assignable to parameter of type 'number'.
+	function assert(diagnostics, expectedFilePathRe) {
+		const {fileName, message, severity, line, column} = diagnostics[0];
+		t.true(new RegExp(expectedFilePathRe).test(fileName));
+		t.is(
+			message,
+			`Argument of type 'number | null' is not assignable to parameter of type 'number'.
   Type \'null\' is not assignable to type 'number'.`
+		);
+		t.is(severity, 'error');
+		t.is(line, 4);
+		t.is(column, 19);
+	}
+
+	assert(
+		await m({cwd: path.join(__dirname, 'fixtures/failure-strict-null-checks')}),
+		'failure-strict-null-checks\\/index.test-d.ts$'
+	);
+	assert(
+		await m({cwd: path.join(__dirname, 'fixtures/failure-strict-null-checks-as-default-config-value')}),
+		'failure-strict-null-checks-as-default-config-value\\/index.test-d.ts$'
 	);
-	t.is(severity, 'error');
-	t.is(line, 4);
-	t.is(column, 19);
 });
 
 test('pass in loose mode when strict mode is disabled in settings', async t => {