Rewrite in TypeScript (#1)

.gitignore

@@ -1,2 +1,5 @@
 node_modules
 yarn.lock
+.nyc_output
+coverage
+dist

.travis.yml

@@ -3,3 +3,5 @@ node_js:
   - '8'
   - '6'
   - '4'
+after_script:
+  - './node_modules/.bin/nyc report --reporter=text-lcov > coverage.lcov && ./node_modules/.bin/codecov'

example.js

@@ -1,5 +1,5 @@
 'use strict';
-const ow = require('.');
+const ow = require('./dist');
 
 const fn = (input, options) => {
 	ow(input, ow.string.minLength(10));

index.js

@@ -1,66 +0,0 @@
-'use strict';
-const is = require('@sindresorhus/is');
-
-class ArgumentError extends Error {
-	constructor(message, context) {
-		super(message);
-		// TODO: Node does not preserve the error name in output when using the below, why?
-		//Error.captureStackTrace(this, context);
-		this.name = 'ArgumentError';
-	}
-}
-
-const ow = (value, predicate) => {
-	for (const validator of predicate.context.validators) {
-		const result = validator(value);
-		if (result) {
-			// TODO: Modify the stack output to show the original `ow()` call instead of this `throw` statement
-			throw new ArgumentError(result, ow);
-		}
-	}
-};
-
-const newInstance = (fn, context) => {
-	const instance = fn(context);
-	instance.context = context;
-	return instance;
-};
-
-const stringPredicates = context => ({
-	minLength: number => {
-		context.validators.push(value => {
-			if (value.length < number) {
-				return `Expected string length to be minimum ${number}`;
-			}
-		});
-		return newInstance(stringPredicates, context);
-	},
-	get alphanumeric() {
-		context.validators.push(value => {
-			if (/[a-z\d]/gi.test(value)) {
-				return `Expected string to contain only alphanumeric characters but received \`${value}\``;
-			}
-		});
-		return newInstance(stringPredicates, context);
-	}
-});
-
-Object.defineProperty(ow, 'string', {
-	enumerable: true,
-	get() {
-		const instance = newInstance(stringPredicates, {
-			validators: []
-		});
-
-		instance.context.validators.push(value => {
-			// TODO: Create a generic function for all types that can be used here
-			if (!is.string(value)) {
-				return `Expected argument to be of type \`string\` but received type \`${is(value)}\``;
-			}
-		});
-
-		return instance;
-	}
-});
-
-module.exports = ow;

package.json

@@ -9,15 +9,19 @@
 		"email": "sindresorhus@gmail.com",
 		"url": "sindresorhus.com"
 	},
+	"main": "dist/index.js",
+	"typings": "dist/index.d.ts",
 	"engines": {
 		"node": ">=4"
 	},
 	"scripts": {
-		"test": "xo && ava"
+		"prerelease": "npm run build",
+		"pretest": "npm run build -- --sourceMap",
+		"test": "nyc ava dist/test",
+		"build": "del dist && tsc -p tsconfig.json --declaration"
 	},
 	"files": [
-		"index.js",
-		"example.js"
+		"dist"
 	],
 	"keywords": [
 		"type",
@@ -43,7 +47,11 @@
 		"@sindresorhus/is": "^0.2.0"
 	},
 	"devDependencies": {
+		"@types/node": "^8.0.31",
 		"ava": "*",
-		"xo": "*"
+		"codecov": "^2.3.0",
+		"del-cli": "^1.1.0",
+		"nyc": "^11.2.1",
+		"typescript": "^2.5.3"
 	}
 }

source/index.ts

@@ -0,0 +1,3 @@
+import { ow } from './ow';
+
+export = ow;

source/lib/argument-error.ts

@@ -0,0 +1,8 @@
+export class ArgumentError extends Error {
+	constructor(message, context) {
+		super(message);
+		// TODO: Node does not preserve the error name in output when using the below, why?
+		//Error.captureStackTrace(this, context);
+		this.name = 'ArgumentError';
+	}
+}

source/lib/predicates/predicate.ts

@@ -0,0 +1,20 @@
+import * as is from '@sindresorhus/is';
+
+export type Validator = (value: any) => string | undefined;
+
+export interface Context {
+	validators: Validator[];
+}
+
+export class Predicate {
+	constructor(
+		type: string,
+		public context: Context = { validators: [] }
+	) {
+		this.context.validators.push(value => {
+			if (!is[type](value)) {
+				return `Expected argument to be of type \`${type}\` but received type \`${is(value)}\``;
+			}
+		});
+	}
+}

source/lib/predicates/string.ts

@@ -0,0 +1,36 @@
+import { Predicate, Context } from './predicate';
+
+export class StringPredicate extends Predicate {
+
+	constructor(context?: Context) {
+		super('string', context);
+	}
+
+	/**
+	 * Test a string to have a minimum length.
+	 *
+	 * @param number The minimum length of the string.
+	 */
+	minLength(number: number) {
+		this.context.validators.push(value => {
+			if (value.length < number) {
+				return `Expected string length to be minimum ${number}`;
+			}
+		});
+
+		return this;
+	}
+
+	/**
+	 * Test a string to be alphanumeric.
+	 */
+	get alphanumeric() {
+		this.context.validators.push(value => {
+			if (!/^[a-z\d]+$/i.test(value)) {
+				return `Expected string to contain only alphanumeric characters but received \`${value}\``;
+			}
+		});
+
+		return this;
+	}
+}

source/ow.ts

@@ -0,0 +1,24 @@
+import * as is from '@sindresorhus/is';
+import { ArgumentError } from './lib/argument-error';
+import { Predicate } from './lib/predicates/predicate';
+import { StringPredicate } from './lib/predicates/string';
+
+export interface Ow {
+	(value: any, predicate: Predicate): void;
+	/**
+	 * Test the value to be a string.
+	 */
+	string?: StringPredicate;
+}
+
+export const ow: Ow = (value: any, predicate: Predicate) => {
+	for (const validator of predicate.context.validators) {
+		const result = validator(value);
+		if (result) {
+			// TODO: Modify the stack output to show the original `ow()` call instead of this `throw` statement
+			throw new ArgumentError(result, ow);
+		}
+	}
+};
+
+ow.string = new StringPredicate();

source/test/string.ts

@@ -0,0 +1,18 @@
+import test from 'ava';
+import * as m from '..';
+
+test('string', t => {
+	t.notThrows(() => m('foo', m.string));
+	t.throws(() => m(12, m.string), 'Expected argument to be of type `string` but received type `number`');
+});
+
+test('string.minLength', t => {
+	t.notThrows(() => m('foo', m.string.minLength(2)));
+	t.notThrows(() => m('foo', m.string.minLength(3)));
+	t.throws(() => m('foo', m.string.minLength(4)), 'Expected string length to be minimum 4');
+});
+
+test('string.alphanumeric', t => {
+	t.notThrows(() => m('Foo123', m.string.alphanumeric));
+	t.throws(() => m('Foo123!', m.string.alphanumeric), 'Expected string to contain only alphanumeric characters but received `Foo123!`');
+});

test.js

@@ -1,6 +0,0 @@
-import test from 'ava';
-import m from '.';
-
-test('', t => {
-
-});

tsconfig.json

@@ -0,0 +1,20 @@
+{
+	"compilerOptions": {
+		"target": "es2016",
+		"module": "commonjs",
+		"declaration": false,
+		"removeComments": false,
+		"pretty": true,
+		"allowUnreachableCode": false,
+		"allowUnusedLabels": false,
+		"noImplicitAny": false,
+		"noImplicitUseStrict": false,
+		"noFallthroughCasesInSwitch": true,
+		"allowSyntheticDefaultImports": true,
+		"outDir": "dist"
+	},
+	"exclude": [
+		"node_modules",
+		"dist"
+	]
+}