Add WeakMap predicate (#43)

source/index.ts

@@ -7,6 +7,7 @@ import {ArrayPredicate} from './lib/predicates/array';
 import {DatePredicate} from './lib/predicates/date';
 import {ErrorPredicate} from './lib/predicates/error';
 import {MapPredicate} from './lib/predicates/map';
+import {WeakMapPredicate} from './lib/predicates/weak-map';
 import {SetPredicate} from './lib/predicates/set';
 import {WeakSetPredicate} from './lib/predicates/weak-set';
 
@@ -71,6 +72,10 @@ export interface Ow {
 	 * Test the value to be a Map.
 	 */
 	readonly map: MapPredicate;
+	/**
+	 * Test the value to be a WeakMap.
+	 */
+	readonly weakMap: WeakMapPredicate;
 	/**
 	 * Test the value to be a Set.
 	 */
@@ -198,6 +203,9 @@ Object.defineProperties(main, {
 	map: {
 		get: () => new MapPredicate()
 	},
+	weakMap: {
+		get: () => new WeakMapPredicate()
+	},
 	set: {
 		get: () => new SetPredicate()
 	},

source/lib/predicates/weak-map.ts

@@ -0,0 +1,47 @@
+import {Predicate, Context} from './predicate';
+
+export class WeakMapPredicate extends Predicate<WeakMap<any, any>> {
+	constructor(context?: Context) {
+		super('weakMap', context);
+	}
+
+	/**
+	 * Test a WeakMap to include all the provided keys. The keys are tested by identity, not structure.
+	 *
+	 * @param keys The keys that should be a key in the WeakMap.
+	 */
+	hasKeys(...keys: any[]) {
+		const missingKeys: any[] = [];
+
+		return this.addValidator({
+			message: () => `Expected WeakMap to have keys \`${JSON.stringify(missingKeys)}\``,
+			validator: map => {
+				for (const key of keys) {
+					if (map.has(key)) {
+						continue;
+					}
+
+					missingKeys.push(key);
+
+					if (missingKeys.length === 5) {
+						return false;
+					}
+				}
+
+				return missingKeys.length === 0;
+			}
+		});
+	}
+
+	/**
+	 * Test a WeakMap to include any of the provided keys. The keys are tested by identity, not structure.
+	 *
+	 * @param keys The keys that could be a key in the WeakMap.
+	 */
+	hasAnyKeys(...keys: any[]) {
+		return this.addValidator({
+			message: () => `Expected WeakMap to have any key of \`${JSON.stringify(keys)}\``,
+			validator: map => keys.some(key => map.has(key))
+		});
+	}
+}

source/test/weak-map.ts

@@ -0,0 +1,30 @@
+import test from 'ava';
+import m from '..';
+
+test('weakMap', t => {
+	t.notThrows(() => m(new WeakMap(), m.weakMap));
+	t.notThrows(() => m(new WeakMap([[{foo: 'bar'}, '🦄']]), m.weakMap));
+	t.throws(() => m(12 as any, m.weakMap), 'Expected argument to be of type `weakMap` but received type `number`');
+});
+
+test('weakMap.hasKeys', t => {
+	const unicorn: any = {unicorn: true};
+	const rainbow: any = {rainbow: true};
+	const keys = [{x: 1}, {x: 2}, {x: 3}, {x: 4}, {x: 5}, {x: 6}, {x: 7}, {x: 8}, {x: 9}, {x: 10}];
+
+	t.notThrows(() => m(new WeakMap([[unicorn, '🦄']]), m.weakMap.hasKeys(unicorn)));
+	t.throws(() => m(new WeakMap([[{rainbow: true}, '🌈']]), m.weakMap.hasKeys({rainbow: true})), 'Expected WeakMap to have keys `[{"rainbow":true}]`');
+	t.throws(() => m(new WeakMap([[unicorn, '🦄'], [rainbow, '🌈']]), m.weakMap.hasKeys(unicorn, {rainbow: true})), 'Expected WeakMap to have keys `[{"rainbow":true}]`');
+	t.throws(() => m(new WeakMap([[keys[0], 1], [keys[2], 3]]), m.weakMap.hasKeys(...keys)), 'Expected WeakMap to have keys `[{"x":2},{"x":4},{"x":5},{"x":6},{"x":7}]`');
+});
+
+test('weakMap.hasAnyKeys', t => {
+	const unicorn: any = {unicorn: true};
+	const rainbow: any = {rainbow: true};
+	const rocket: any = {rocket: true};
+
+	t.notThrows(() => m(new WeakMap([[unicorn, '🦄']]), m.weakMap.hasAnyKeys(unicorn, rainbow)));
+	t.notThrows(() => m(new WeakMap([[unicorn, '🦄'], [rainbow, '🌈']]), m.weakMap.hasAnyKeys(unicorn)));
+	t.notThrows(() => m(new WeakMap([[unicorn, '🦄'], [rainbow, '🌈']]), m.weakMap.hasAnyKeys(unicorn, rainbow, rocket)));
+	t.throws(() => m(new WeakMap([[unicorn, '🦄'], [rainbow, '🌈']]), m.weakMap.hasAnyKeys(rocket)), 'Expected WeakMap to have any key of `[{"rocket":true}]`');
+});