expect-more

Curried JavaScript Type Testing Library with Zero Dependencies

Installation

npm install expect-more --save-dev

Usage

import { endsWith, isWithinRange } from 'expect-more';

const result: boolean = endsWith('Script', 'JavaScript');
// => true

const endsWithScript = endsWith('Script');
endsWithScript('JavaScript');
// => true

isWithinRange(10, 20, 21);
// => false

[0, 1, 1, 2, 3, 5, 8, 13, 21, 34].filter(isWithinRange(5, 15));
// => [5, 8, 13]

API: expect-more

General

declare const isBoolean: (value: unknown) => value is boolean;
declare const isFalse: (value: unknown) => value is false;
declare const isNull: (value: unknown) => value is null;
declare const isRegExp: (value: unknown) => value is RegExp;
declare const isTrue: (value: unknown) => value is true;
declare const isUndefined: (value: unknown) => value is undefined;

Functions

declare const isAsyncFunction: <T = (...args: any[]) => Promise<any>>(
  value: unknown,
) => value is T;
declare const isFunction: <T = (...args: any[]) => any>(value: unknown) => value is T;
declare const isGeneratorFunction: <T = Generator>(value: unknown) => value is T;
declare const throwsAnyError: <T = (...args: any[]) => any>(value: unknown) => value is T;
declare const throwsErrorOfType: <T = (...args: any[]) => any>(
  typeName: string,
  value: unknown,
) => value is T;

Objects

declare const hasMember: <T = any>(memberName: string, value: unknown) => value is T;
declare const isEmptyObject: <T = any>(value: unknown) => value is T;
declare const isNil: (value: unknown) => value is undefined | null;
declare const isNonEmptyObject: <T = any>(value: unknown) => value is T;
declare const isObject: <T = any>(value: unknown) => value is T;
declare const isWalkable: <T = any>(value: unknown) => value is T;

Arrays

declare const isArray: <T extends any[] = any[]>(value: unknown) => value is T;
declare const isArrayIncludingAllOf: <T extends any[] = any[]>(needed: any[], value: unknown) => value is T;
declare const isArrayIncludingAnyOf: <T extends any[] = any[]>(needed: any[], value: unknown) => value is T;
declare const isArrayIncludingOnly: <T extends any[] = any[]>(needed: any[], value: unknown) => value is T;
declare const isArrayOfBooleans: (value: unknown) => value is boolean[];
declare const isArrayOfNumbers: (value: unknown) => value is number[];
declare const isArrayOfObjects: <T extends any[] = any[]>(value: unknown) => value is T;
declare const isArrayOfSize: <T extends any[] = any[]>(
  size: number,
  value: unknown,
) => value is T;
declare const isArrayOfStrings: (value: unknown) => value is string[];
declare const isEmptyArray: <T extends [] = []>(any) => value is T;
declare const isNonEmptyArray: <T extends any[] = any[]>(value: unknown) => value is T;

Dates

declare const isAfter: (other: Date, value: unknown) => value is Date;
declare const isBefore: (other: Date, value: unknown) => value is Date;
declare const isDate: (value: unknown) => value is Date;
declare const isDateBetween: (floor: Date, ceiling: Date, value: unknown) => value is Date;
declare const isDateInMonth: (index: number, value: unknown) => value is Date;
declare const isDateInYear: (year: number, value: unknown) => value is Date;
declare const isDateOnDayOfMonth: (day: number, value: unknown) => value is Date;
declare const isDateOnDayOfWeek: (index: number, value: unknown) => value is Date;
declare const isDateOnOrAfter: (other: Date, value: unknown) => value is Date;
declare const isDateOnOrBefore: (other: Date, value: unknown) => value is Date;
declare const isValidDate: (value: unknown) => value is Date;

Numbers

declare const isCalculable: (value: unknown) => value is number;
declare const isDecimalNumber: (value: unknown) => value is number;
declare const isDivisibleBy: (other: number, value: unknown) => value is number;
declare const isEvenNumber: (value: unknown) => value is number;
declare const isGreaterThanOrEqualTo: (other: number, value: unknown) => value is number;
declare const isLessThanOrEqualTo: (other: number, value: unknown) => value is number;
declare const isNear: (other: number, epsilon: number, value: unknown) => value is number;
declare const isNegativeNumber: (value: unknown) => value is number;
declare const isNumber: (value: unknown) => value is number;
declare const isOddNumber: (value: unknown) => value is number;
declare const isPositiveNumber: (value: unknown) => value is number;
declare const isWholeNumber: (value: unknown) => value is number;
declare const isWithinRange: (
  floor: number,
  ceiling: number,
  value: unknown,
) => value is number;

Strings

declare const endsWith: (other: string, value: unknown) => value is string;
declare const isEmptyString: (value: unknown) => value is string;
declare const isIso8601: (value: unknown) => value is string;
declare const isJsonString: (value: unknown) => value is string;
declare const isLongerThan: (other: string, value: unknown) => value is string;
declare const isNonEmptyString: (value: unknown) => value is string;
declare const isSameLengthAs: (other: string, value: unknown) => value is string;
declare const isShorterThan: (other: string, value: unknown) => value is string;
declare const isString: (value: unknown) => value is string;
declare const isVisibleString: (value: unknown) => value is string;
declare const isWhitespace: (value: unknown) => value is string;
declare const startsWith: (other: string, value: unknown) => value is string;

API: expect-more/gen

declare const withMissingBranches: (value: object | any[]) => Generator;
declare const withMissingLeaves: (value: object | any[]) => Generator;
declare const withMissingNodes: (value: object | any[]) => Generator;
declare const withNullBranches: (value: object | any[]) => Generator;
declare const withNullLeaves: (value: object | any[]) => Generator;
declare const withNullNodes: (value: object | any[]) => Generator;