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https://github.com/trekhleb/javascript-algorithms.git
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90 lines
2.7 KiB
JavaScript
90 lines
2.7 KiB
JavaScript
import HashTable from '../HashTable';
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describe('HashTable', () => {
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it('should create hash table of certain size', () => {
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const defaultHashTable = new HashTable();
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expect(defaultHashTable.buckets.length).toBe(32);
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const biggerHashTable = new HashTable(64);
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expect(biggerHashTable.buckets.length).toBe(64);
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});
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it('should generate proper hash for specified keys', () => {
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const hashTable = new HashTable();
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expect(hashTable.hash('a')).toBe(1);
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expect(hashTable.hash('b')).toBe(2);
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expect(hashTable.hash('abc')).toBe(6);
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});
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it('should set, read and delete data with collisions', () => {
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const hashTable = new HashTable(3);
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expect(hashTable.hash('a')).toBe(1);
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expect(hashTable.hash('b')).toBe(2);
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expect(hashTable.hash('c')).toBe(0);
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expect(hashTable.hash('d')).toBe(1);
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hashTable.set('a', 'sky-old');
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hashTable.set('a', 'sky');
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hashTable.set('b', 'sea');
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hashTable.set('c', 'earth');
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hashTable.set('d', 'ocean');
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expect(hashTable.has('x')).toBe(false);
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expect(hashTable.has('b')).toBe(true);
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expect(hashTable.has('c')).toBe(true);
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const stringifier = value => `${value.key}:${value.value}`;
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expect(hashTable.buckets[0].toString(stringifier)).toBe('c:earth');
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expect(hashTable.buckets[1].toString(stringifier)).toBe('a:sky,d:ocean');
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expect(hashTable.buckets[2].toString(stringifier)).toBe('b:sea');
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expect(hashTable.get('a')).toBe('sky');
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expect(hashTable.get('d')).toBe('ocean');
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expect(hashTable.get('x')).not.toBeDefined();
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hashTable.delete('a');
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expect(hashTable.delete('not-existing')).toBeNull();
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expect(hashTable.get('a')).not.toBeDefined();
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expect(hashTable.get('d')).toBe('ocean');
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hashTable.set('d', 'ocean-new');
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expect(hashTable.get('d')).toBe('ocean-new');
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});
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it('should be possible to add objects to hash table', () => {
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const hashTable = new HashTable();
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hashTable.set('objectKey', { prop1: 'a', prop2: 'b' });
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const object = hashTable.get('objectKey');
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expect(object).toBeDefined();
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expect(object.prop1).toBe('a');
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expect(object.prop2).toBe('b');
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});
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it('should track actual keys', () => {
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const hashTable = new HashTable(3);
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hashTable.set('a', 'sky-old');
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hashTable.set('a', 'sky');
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hashTable.set('b', 'sea');
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hashTable.set('c', 'earth');
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hashTable.set('d', 'ocean');
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expect(hashTable.getKeys()).toEqual(['a', 'b', 'c', 'd']);
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expect(hashTable.has('a')).toBe(true);
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expect(hashTable.has('x')).toBe(false);
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hashTable.delete('a');
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expect(hashTable.has('a')).toBe(false);
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expect(hashTable.has('b')).toBe(true);
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expect(hashTable.has('x')).toBe(false);
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});
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});
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