@theia/core/src/common/fuzzy-search.spec.ts

Theia is a cloud & desktop IDE framework implemented in TypeScript.

// *****************************************************************************
// Copyright (C) 2018 TypeFox and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// http://www.eclipse.org/legal/epl-2.0.
//
// This Source Code may also be made available under the following Secondary
// Licenses when the conditions for such availability set forth in the Eclipse
// Public License v. 2.0 are satisfied: GNU General Public License, version 2
// with the GNU Classpath Exception which is available at
// https://www.gnu.org/software/classpath/license.html.
//
// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
// *****************************************************************************

import { expect } from 'chai';
import { FuzzySearch } from './fuzzy-search';

describe('fuzzy-search', () => {

    ([
        {
            pattern: 'a',
            items: ['alma'],
            expected: [
                {
                    item: 'alma',
                    ranges: [
                        { offset: 0, length: 1 }
                    ]
                }
            ]
        },
        {
            pattern: 'a',
            items: ['körte'],
            expected: []
        },
        {
            pattern: 'bcn',
            items: ['baconing', 'narwhal', 'a mighty bear canoe'],
            expected: [
                {
                    item: 'baconing',
                    ranges: [
                        { offset: 0, length: 1 },
                        { offset: 2, length: 1 },
                        { offset: 4, length: 1 }
                    ]
                },
                {
                    item: 'a mighty bear canoe',
                    ranges: [
                        { offset: 9, length: 1 },
                        { offset: 14, length: 1 },
                        { offset: 16, length: 1 }
                    ]
                }
            ]
        }
    ] as {
        readonly pattern: string,
        readonly items: string[],
        readonly expected: FuzzySearch.Match<string>[]
    }[]).forEach(test => {
        const { pattern, items, expected } = test;
        it(`should match ${expected.length} item${expected.length === 1 ? '' : 's'} when filtering [${items.join(', ')}] with pattern: '${pattern}'`, async () => {
            expectSearch(await search(pattern, items), expected);
        });
    });

    ([
        // "con" prefix matches (configs, CONTRIBUTING.MD) first, then substring matches (base.tsconfig.json, tsconfig.json), then fuzzy-only (base.nyc.json)
        ['con', ['configs', 'base.tsconfig.json', 'tsconfig.json', 'base.nyc.json', 'CONTRIBUTING.MD'],
            ['configs', 'CONTRIBUTING.MD', 'base.tsconfig.json', 'tsconfig.json', 'base.nyc.json']],
        ['bcn', ['baconing', 'narwhal', 'a mighty bear canoe'], ['baconing', 'a mighty bear canoe']]
    ] as ([string, string[], string[]])[]).forEach(test => {
        const [pattern, items, expected] = test;
        it(`should match the order of items after the filtering with pattern: '${pattern}'`, async () => {
            expectOrder(await search(pattern, items), expected || items);
        });
    });

    it('should rank substring matches before fuzzy-only matches', async () => {
        const results = await search('font', ['reformatting', 'fontSize', 'fontFamily']);
        // "reformatting" contains f-o-n-t scattered but not as substring; fontSize/fontFamily do
        expectOrder(results, ['fontSize', 'fontFamily']);
    });

    it('should preserve original order for equal-score fuzzy-only matches', async () => {
        // Both are fuzzy-only matches for "bcn" with different scores from the fuzzy library;
        // when scores are equal, original array order (index) should be preserved.
        const results = await search('ab', ['xab', 'yab']);
        expectOrder(results, ['xab', 'yab']);
    });

    it('should highlight contiguous substring range instead of scattered fuzzy ranges', async () => {
        const results = await search('works', ['browser-only-workspace-server.ts']);
        expect(results).to.have.length(1);
        // "works" appears at index 13 in "browser-only-workspace-server.ts"
        expect(results[0].ranges).to.deep.equal([{ offset: 13, length: 5 }]);
    });

    function expectOrder(actual: FuzzySearch.Match<string>[], expected: string[]): void {
        expect(actual.map(result => result.item)).to.be.deep.equal(expected);
    }

    function expectSearch(actual: FuzzySearch.Match<string>[], expected: FuzzySearch.Match<string>[]): void {
        expect(actual).to.be.deep.equal(expected);
    }

    async function search(pattern: string, items: string[]): Promise<FuzzySearch.Match<string>[]> {
        return new FuzzySearch().filter({
            items,
            pattern,
            transform: arg => arg
        });
    }

});