Add linting rules - fixes #7 (#8)

package.json

@@ -17,7 +17,8 @@
 	"scripts": {
 		"prerelease": "npm run build",
 		"pretest": "npm run build -- --sourceMap",
-		"test": "nyc ava dist/test",
+		"test": "npm run lint && nyc ava dist/test",
+		"lint": "tslint --type-check -p tsconfig.json \"source/**/*.ts\"",
 		"build": "del dist && tsc -p tsconfig.json --declaration"
 	},
 	"files": [
@@ -52,6 +53,7 @@
 		"codecov": "^2.3.0",
 		"del-cli": "^1.1.0",
 		"nyc": "^11.2.1",
+		"tslint": "^5.7.0",
 		"typescript": "^2.5.3"
 	}
 }

source/lib/argument-error.ts

@@ -2,7 +2,7 @@ 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);
+		// Error.captureStackTrace(this, context);
 		this.name = 'ArgumentError';
 	}
 }

source/lib/predicates/predicate.ts

@@ -1,8 +1,8 @@
 import * as is from '@sindresorhus/is';
 
 export interface Validator<T> {
-	message: (value: T) => string;
-	validator: (value: T) => boolean;
+	message(value: T): string;
+	validator(value: T): boolean;
 }
 
 export interface Context {
@@ -26,6 +26,11 @@ export class Predicate<T = any> {
 		return this.context.validators;
 	}
 
+	/**
+	 * Register a new validator.
+	 *
+	 * @param validator Validator to register.
+	 */
 	protected addValidator(validator: Validator<T>) {
 		this.context.validators.push(validator);
 

source/lib/predicates/string.ts

@@ -9,12 +9,12 @@ export class StringPredicate extends Predicate<string> {
 	/**
 	 * Test a string to have a minimum length.
 	 *
-	 * @param number The minimum length of the string.
+	 * @param length The minimum length of the string.
 	 */
-	minLength(number: number) {
+	minLength(length: number) {
 		return this.addValidator({
-			message: () => `Expected string length to be minimum ${number}`,
-			validator: value => value.length >= number
+			message: () => `Expected string length to be minimum ${length}`,
+			validator: value => value.length >= length
 		});
 	}
 

source/ow.ts

@@ -1,4 +1,3 @@
-import * as is from '@sindresorhus/is';
 import { ArgumentError } from './lib/argument-error';
 import { Predicate, validatorSymbol } from './lib/predicates/predicate';
 import { StringPredicate } from './lib/predicates/string';
@@ -8,18 +7,19 @@ export interface Ow {
 	/**
 	 * Test the value to be a string.
 	 */
-	string?: StringPredicate;
+	string: StringPredicate;
 }
 
-export const ow: Ow = (value: any, predicate: Predicate) => {
-	for (const { validator, message } of predicate[validatorSymbol]) {
-		if (!validator(value)) {
-			// TODO: Modify the stack output to show the original `ow()` call instead of this `throw` statement
-			throw new ArgumentError(message(value), ow);
+export const ow: Ow = Object.assign(
+	(value: any, predicate: Predicate) => {
+		for (const { validator, message } of predicate[validatorSymbol]) {
+			if (!validator(value)) {
+				// TODO: Modify the stack output to show the original `ow()` call instead of this `throw` statement
+				throw new ArgumentError(message(value), ow);
+			}
 		}
+	},
+	{
+		string: new StringPredicate()
 	}
-};
-
-Object.defineProperty(ow, 'string', {
-	get: () => new StringPredicate()
-});
+);

tsconfig.json

@@ -11,6 +11,7 @@
 		"noImplicitUseStrict": false,
 		"noFallthroughCasesInSwitch": true,
 		"allowSyntheticDefaultImports": true,
+		"strictNullChecks": true,
 		"outDir": "dist"
 	},
 	"exclude": [

tslint.json

@@ -0,0 +1,114 @@
+{
+	"rules": {
+		"adjacent-overload-signatures": true,
+		"no-empty-interface": true,
+		"no-import-side-effect": true,
+		"no-internal-module": true,
+		"no-namespace": true,
+		"no-non-null-assertion": true,
+		"no-parameter-reassignment": true,
+		"no-reference": true,
+		"no-unnecessary-type-assertion": true,
+		"no-var-requires": true,
+		"only-arrow-functions": true,
+		"prefer-for-of": true,
+		"promise-function-async": true,
+		"await-promise": true,
+		"curly": true,
+		"no-arg": true,
+		"no-conditional-assignment": true,
+		"no-construct": true,
+		"no-debugger": true,
+		"no-duplicate-super": true,
+		"no-duplicate-variable": true,
+		"no-empty": true,
+		"no-eval": true,
+		"no-floating-promises": true,
+		"no-for-in-array": true,
+		"no-invalid-template-strings": true,
+		"no-invalid-this": false,
+		"no-misused-new": true,
+		"no-shadowed-variable": true,
+		"no-sparse-arrays": true,
+		"no-string-literal": true,
+		"no-string-throw": true,
+		"no-switch-case-fall-through": true,
+		"no-this-assignment": true,
+		"no-unsafe-finally": true,
+		"no-unused-expression": true,
+		"no-unused-variable": true,
+		"no-use-before-declare": true,
+		"no-var-keyword": true,
+		"prefer-object-spread": true,
+		"radix": true,
+		"restrict-plus-operands": true,
+		"strict-type-predicates": true,
+		"switch-default": true,
+		"triple-equals": true,
+		"typeof-compare": true,
+		"use-default-type-parameter": true,
+		"use-isnan": true,
+		"deprecation": true,
+		"eofline": true,
+		"indent": [true, "tabs"],
+		"no-default-export": true,
+		"no-duplicate-imports": true,
+		"no-require-imports": true,
+		"prefer-const": true,
+		"trailing-comma": false,
+		"array-type": [true, "array"],
+		"arrow-parens": [true, "ban-single-arg-parens"],
+		"arrow-return-shorthand": true,
+		"binary-expression-operand-order": true,
+		"callable-types": true,
+		"class-name": true,
+		"comment-format": [true, "check-space", "check-uppercase"],
+		"completed-docs": [true, "methods"],
+		"encoding": true,
+		"import-spacing": true,
+		"interface-over-type-literal": true,
+		"newline-before-return": true,
+		"new-parens": true,
+		"no-angle-bracket-type-assertion": true,
+		"no-boolean-literal-compare": true,
+		"no-consecutive-blank-lines": true,
+		"no-irregular-whitespace": true,
+		"no-reference-import": true,
+		"no-trailing-whitespace": true,
+		"no-unnecessary-initializer": true,
+		"no-unnecessary-qualifier": true,
+		"number-literal-format": true,
+		"object-literal-key-quotes": [true, "as-needed"],
+		"object-literal-shorthand": true,
+		"one-variable-per-declaration": true,
+		"prefer-method-signature": true,
+		"prefer-template": [true, "allow-single-concat"],
+		"quotemark": [true, "single", "avoid-template"],
+		"semicolon": true,
+		"space-before-function-paren": [
+			true,
+			{
+				"anonymous": "never",
+				"named": "never",
+				"asyncArrow": "always"
+			}
+		],
+		"space-within-parens": [true, 0],
+		"switch-final-break": true,
+		"type-literal-delimiter": true,
+		"variable-name": [true, "check-format", "ban-keywords"],
+		"whitespace": [
+			true,
+			"check-branch",
+			"check-decl",
+			"check-operator",
+			"check-module",
+			"check-separator",
+			"check-rest-spread",
+			"check-type",
+			"check-typecast",
+			"check-type-operator",
+			"check-preblock"
+		]
+	}
+}