Add type definition tests

Author: SamVerschueren

index.d.ts

@@ -1,6 +1,6 @@
-export type Replacer = (key: string, value: any) => void;
+export type Replacer = (key: string, value: any) => number | string | boolean | object | null | undefined;
 export type SortKeys = (a: string, b: string) => number;
-export type JSONStringifyable = object | number | string;
+export type JSONStringifyable = object | number | string | boolean;
 
 export interface Options {
 	/**

index.test-d.ts

@@ -0,0 +1,60 @@
+import {expectType} from 'tsd-check';
+import writeJsonFile, {sync, Replacer, SortKeys, JSONStringifyable} from '.';
+
+const replacer: Replacer = (key: string) => {
+	if (key === 'unicorn') {
+		return {rainbow: '🌈'};
+	} else if (key === 'rainbow') {
+		return () => 'foo';
+	}
+
+	return key.toUpperCase();
+};
+
+const sortKeys: SortKeys = (a: string, b: string) => a.length - b.length;
+
+(async () => {
+	expectType<JSONStringifyable>('🦄');
+	expectType<JSONStringifyable>(1);
+	expectType<JSONStringifyable>(true);
+	expectType<JSONStringifyable>(new Date());
+	expectType<JSONStringifyable>(['hello', 'world']);
+	expectType<JSONStringifyable>({unicorn: '🦄'});
+
+	expectType<SortKeys>(() => 1);
+	expectType<SortKeys>((a: string) => a.length);
+	expectType<SortKeys>((a: string, b: string) => a.length - b.length);
+
+	expectType<Replacer>(() => 1);
+	expectType<Replacer>(() => 'unicorn');
+	expectType<Replacer>(() => true);
+	expectType<Replacer>(() => null);
+	expectType<Replacer>(() => undefined);
+	expectType<Replacer>(() => ({unicorn: '🦄'}));
+	expectType<Replacer>(() => () => 'foo');
+	expectType<Replacer>((key: string) => key.toUpperCase());
+
+	expectType<void>(await writeJsonFile('unicorn.json', {unicorn: '🦄'}));
+	expectType<void>(await writeJsonFile('unicorn.json', '🦄'));
+	expectType<void>(await writeJsonFile('date.json', new Date()));
+	expectType<void>(await writeJsonFile('unicorn.json', {unicorn: '🦄'}, {detectIndent: true}));
+	expectType<void>(await writeJsonFile('unicorn.json', {unicorn: '🦄'}, {indent: ' '}));
+	expectType<void>(await writeJsonFile('unicorn.json', {unicorn: '🦄'}, {indent: 4}));
+	expectType<void>(await writeJsonFile('unicorn.json', {unicorn: '🦄'}, {mode: 0o666}));
+	expectType<void>(await writeJsonFile('unicorn.json', {unicorn: '🦄'}, {replacer}));
+	expectType<void>(await writeJsonFile('unicorn.json', {unicorn: '🦄'}, {replacer: ['unicorn', 1]}));
+	expectType<void>(await writeJsonFile('unicorn.json', {unicorn: '🦄'}, {sortKeys}));
+	expectType<void>(await writeJsonFile('unicorn.json', {unicorn: '🦄'}, {sortKeys: true}));
+
+	expectType<void>(sync('unicorn.json', {unicorn: '🦄'}));
+	expectType<void>(sync('unicorn.json', '🦄'));
+	expectType<void>(sync('date.json', new Date()));
+	expectType<void>(sync('unicorn.json', {unicorn: '🦄'}, {detectIndent: true}));
+	expectType<void>(sync('unicorn.json', {unicorn: '🦄'}, {indent: ' '}));
+	expectType<void>(sync('unicorn.json', {unicorn: '🦄'}, {indent: 4}));
+	expectType<void>(sync('unicorn.json', {unicorn: '🦄'}, {mode: 0o666}));
+	expectType<void>(sync('unicorn.json', {unicorn: '🦄'}, {replacer}));
+	expectType<void>(sync('unicorn.json', {unicorn: '🦄'}, {replacer: ['unicorn', 1]}));
+	expectType<void>(sync('unicorn.json', {unicorn: '🦄'}, {sortKeys}));
+	expectType<void>(sync('unicorn.json', {unicorn: '🦄'}, {sortKeys: true}));
+})();

package.json

@@ -13,7 +13,7 @@
 		"node": ">=6"
 	},
 	"scripts": {
-		"test": "xo && ava"
+		"test": "xo && tsd-check && ava"
 	},
 	"files": [
 		"index.js",
@@ -44,11 +44,12 @@
 	"devDependencies": {
 		"ava": "*",
 		"tempfile": "^2.0.0",
+		"tsd-check": "^0.1.0",
 		"xo": "*"
 	},
 	"xo": {
 		"ignores": [
-			"index.d.ts"
+			"*.ts"
 		]
 	}
 }