Make it strict by default and add ability to configure compilerOptions

package.json

@@ -42,12 +42,13 @@
 		"eslint-formatter-pretty": "^1.3.0",
 		"meow": "^5.0.0",
 		"path-exists": "^3.0.0",
+		"pkg-conf": "^3.0.0",
 		"read-pkg-up": "^4.0.0",
 		"typescript": "^3.0.1",
 		"update-notifier": "^2.5.0"
 	},
 	"devDependencies": {
-		"@types/node": "^10.7.1",
+		"@types/node": "^11.10.4",
 		"@types/update-notifier": "^2.2.0",
 		"ava": "*",
 		"cpy-cli": "^2.0.0",

source/lib/compiler.ts

@@ -1,10 +1,12 @@
 import * as path from 'path';
+import * as pkgConf from 'pkg-conf';
 import {
 	ScriptTarget,
 	ModuleResolutionKind,
 	flattenDiagnosticMessageText,
 	CompilerOptions,
-	createProgram
+	createProgram,
+	JsxEmit
 } from 'typescript';
 import {Diagnostic, Context} from './interfaces';
 
@@ -13,11 +15,24 @@ const ignoredDiagnostics = new Set<number>([
 	1308 // Support top-level `await`
 ]);
 
-const loadConfig = (): CompilerOptions => {
+const loadConfig = (cwd: string): CompilerOptions => {
+	const config = pkgConf.sync('tsd-check', {
+		cwd,
+		defaults: {
+			compilerOptions: {
+				strict: true,
+				jsx: JsxEmit.React,
+				target: ScriptTarget.ES2017
+			}
+		}
+	});
+
 	return {
-		moduleResolution: ModuleResolutionKind.NodeJs,
-		skipLibCheck: true,
-		target: ScriptTarget.ES2015
+		...config.compilerOptions,
+		...{
+			moduleResolution: ModuleResolutionKind.NodeJs,
+			skipLibCheck: true
+		}
 	};
 };
 
@@ -28,22 +43,26 @@ const loadConfig = (): CompilerOptions => {
  * @returns List of diagnostics
  */
 export const getDiagnostics = (context: Context): Diagnostic[] => {
-	const compilerOptions = loadConfig();
+	const compilerOptions = loadConfig(context.cwd);
 
 	const fileName = path.join(context.cwd, context.testFile);
 
 	const result: Diagnostic[] = [];
 
 	const program = createProgram([fileName], compilerOptions);
 
-	const diagnostics = program.getSemanticDiagnostics().concat(program.getSyntacticDiagnostics());
+	const diagnostics = program
+		.getSemanticDiagnostics()
+		.concat(program.getSyntacticDiagnostics());
 
 	for (const diagnostic of diagnostics) {
 		if (!diagnostic.file || ignoredDiagnostics.has(diagnostic.code)) {
 			continue;
 		}
 
-		const position = diagnostic.file.getLineAndCharacterOfPosition(diagnostic.start as number);
+		const position = diagnostic.file.getLineAndCharacterOfPosition(
+			diagnostic.start as number
+		);
 
 		result.push({
 			fileName: diagnostic.file.fileName,

source/test/fixtures/failure-strict-null-checks/index.d.ts

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

source/test/fixtures/failure-strict-null-checks/index.js

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

source/test/fixtures/failure-strict-null-checks/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/package.json

@@ -0,0 +1,3 @@
+{
+	"name": "foo"
+}

source/test/fixtures/non-strict-check-with-config/index.d.ts

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

source/test/fixtures/non-strict-check-with-config/index.js

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

source/test/fixtures/non-strict-check-with-config/index.test-d.ts

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

source/test/fixtures/non-strict-check-with-config/package.json

@@ -0,0 +1,8 @@
+{
+	"name": "foo",
+	"tsd-check": {
+		"compilerOptions": {
+			"strict": false
+		}
+	}
+}

source/test/test.ts

@@ -43,6 +43,31 @@ test('fail if typings file is not part of `files` list', 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'.
+  Type \'null\' is not assignable to type 'number'.`
+	);
+	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 => {
+	const diagnostics = await m({
+		cwd: path.join(__dirname, 'fixtures/non-strict-check-with-config')
+	});
+
+	t.true(diagnostics.length === 0);
+});
+
 test('return no diagnostics', async t => {
 	const diagnostics = await m({cwd: path.join(__dirname, 'fixtures/success')});