hamjest/lib/matchers/SubstringMatcher.js

A library of composable matchers for defining meaningful and readable assertions in JavaScript.

'use strict';

const _create = require('lodash/create');
const _every = require('lodash/every');
const _filter = require('lodash/filter');
const IsString = require('./IsString');
const assertThat = require('../assertThat');
const is = require('./Is').is;
const string = require('./IsString').string;

function SubstringMatcher(substring, relation, matchesString) {
	assertThat(substring, is(string()));

	return _create(new IsString(), {
		matchesSafely(actual) {
			return matchesString.call(this, actual);
		},
		describeTo(description) {
			description
				.append('a string ')
				.append(relation)
				.append(' ')
				.appendValue(substring);
		},
		describeMismatchSafely(actual, description) {
			description
				.append('was ')
				.appendValue(actual);
		},
		getExpectedForDiff() { return substring; },
		formatActualForDiff(actual) { return actual; }
	});
}

SubstringMatcher.containsString = function (substring) {
	return new SubstringMatcher(substring, 'containing', (actualString) => {
		return actualString.indexOf(substring) !== -1;
	});
};

SubstringMatcher.containsStrings = function (...substrings) {
	substrings.map((s) => assertThat(s, is(string())));
	return _create(new IsString(), {
		matchesSafely(actual) {
			return _every(substrings, (s) => actual.indexOf(s) !== -1);
		},
		describeTo(description) {
			description
				.append('a string containing ')
				.appendList('', ', ', '', substrings);
		},
		describeMismatchSafely(actual, description) {
			const notFound = _filter(substrings, (s) => actual.indexOf(s) === -1);
			description
				.appendList('', ', ', '', notFound)
				.append(' could not be found in ')
				.appendValue(actual);
		},
	});
};

SubstringMatcher.startsWith = function (prefix) {
	return new SubstringMatcher(prefix, 'starting with', (actualString) => {
		return actualString.indexOf(prefix) === 0;
	});
};

SubstringMatcher.endsWith = function (suffix) {
	return new SubstringMatcher(suffix, 'ending with', (actualString) => {
		return actualString.indexOf(suffix, actualString.length - suffix.length) !== -1;
	});
};

module.exports = SubstringMatcher;