[DEV-6353] Add function to create delta from one data set to another
The type of the delta must accomodate undefined and null values for array data, as well as null for a key value to represent removing a keymaster
Austin Schaffer
Schaffer, Austin
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26c4367ead
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a4d151ef79
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/**
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* A delta
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*
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* Copyright (C) 2010-2019 R-T Specialty, LLC.
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*
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* This file is part of the Liza Data Collection Framework.
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*
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* liza is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/** The data structure expected for a document's internal key/value store */
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export type Kv<T = any> = Record<string, T[]>;
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/** Possible delta values for Kv array indexes */
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export type DeltaDatum<T> = T | null | undefined;
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/**
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* The constructor type for a delta generating function
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*
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* @param src - the source data set
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* @param dest - the destination data set
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*
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* @return the delta which transforms src to dest
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*/
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export type DeltaConstructor<T = any, U extends Kv<T> = Kv<T>, V extends Kv<T> = U> = (
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src: U,
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dest: V,
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) => DeltaResult<U & V>;
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/** Transform type T to hold possible delta values */
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export type DeltaResult<T> = { [K in keyof T]: DeltaDatum<T[K]> | null };
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/**
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* Create delta to transform from src into dest
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*
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* @param src - the source data set
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* @param dest - the destination data set
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*
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* @return the delta
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*/
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export function createDelta<T, U extends Kv<T>, V extends Kv<T>>(
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src: U,
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dest: V,
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): DeltaResult<U & V>
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{
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const delta: DeltaResult<any> = {};
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// Loop through all keys
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const key_set = new Set(
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Object.keys( src ).concat( Object.keys( dest ) ) );
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key_set.forEach( key =>
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{
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const src_data = src[ key ];
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const dest_data = dest[ key ];
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// If source does not contain the key, use entire dest data
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if ( !src_data || !src_data.length )
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{
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delta[ key ] = dest_data;
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return;
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}
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// If the key no longer exists in dest then nullify this key
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if ( !dest_data || !dest_data.length )
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{
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delta[ key ] = null;
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return;
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}
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// If neither condition above is true then create the key iteratively
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const delta_key = _createDeltaKey( src_data, dest_data );
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if ( delta_key.changed )
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{
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delta[ key ] = delta_key.data;
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}
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} );
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return <DeltaResult<U & V>>delta;
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}
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/**
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* Build the delta key iteratively
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*
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* @param src - the source data array
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* @param dest - the destination data array
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*
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* @return an object with an identical flag and a data array
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*/
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function _createDeltaKey<T>(
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src: T[],
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dest: T[],
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): { changed: boolean, data: DeltaDatum<T>[] }
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{
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const data = [];
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const max_size = Math.max( dest.length, src.length );
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let changed: boolean = false;
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for ( let i = 0; i < max_size; i++ )
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{
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const dest_datum = dest[ i ];
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const src_datum = src[ i ];
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// terminate the key if we don't have a dest value
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if ( dest_datum === undefined )
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{
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changed = true;
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data[ i ] = null;
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break;
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}
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else if ( _deepEqual( dest_datum, src_datum ) )
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{
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data[ i ] = undefined;
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}
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else
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{
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changed = true;
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data[ i ] = dest_datum;
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}
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}
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return {
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changed: changed,
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data: data,
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};
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}
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/**
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* Compare two arrays by index
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*
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* @param a - the first array to compare
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* @param b - the second array to compare
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*/
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function _deepEqual( a: any, b: any ): boolean
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{
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if ( Array.isArray( a ) )
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{
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if ( !Array.isArray( b ) || ( a.length !== b.length ) )
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{
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return false;
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}
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return a.map( ( item, i ) => _deepEqual( item, b[ i ] ) )
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.every( res => res === true );
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}
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return ''+a === ''+b;
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}
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@ -0,0 +1,99 @@
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/**
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* Test the delta generated from two key/value stores
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*
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* Copyright (C) 2010-2019 R-T Specialty, LLC.
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*
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* This file is part of liza.
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*
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* liza is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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import { createDelta as sut, Kv , DeltaResult} from "../../src/bucket/delta";
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import { expect, use as chai_use } from 'chai';
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chai_use( require( 'chai-as-promised' ) );
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interface SutTestCase<T>
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{
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label: string;
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src_data: T;
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dest_data: T;
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expected: DeltaResult<T>;
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}
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describe( 'Delta', () =>
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{
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( <SutTestCase<Kv<string>>[]>[
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{
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label: "No changes are made, key is dropped",
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src_data: { foo: [ 'bar', 'baz' ] },
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dest_data: { foo: [ 'bar', 'baz' ] },
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expected: {},
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},
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{
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label: "Only the unchanged key is dropped",
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src_data: { foo: [ 'bar', 'baz' ], bar: [ 'qwe' ] },
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dest_data: { foo: [ 'bar', 'baz' ], bar: [ 'asd' ] },
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expected: { bar: [ 'asd' ] },
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},
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{
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label: "Changed values are updated by index with old value",
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src_data: { foo: [ "bar", "baz", "quux" ] },
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dest_data: { foo: [ "bar", "quuux" ], moo: [ "cow" ] },
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expected: { foo: [ undefined, "quuux", null ], moo: [ "cow" ] },
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},
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{
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label: "The keys are null when they don't exist in first set",
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src_data: {},
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dest_data: { foo: [ "bar", "quuux" ], moo: [ "cow" ] },
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expected: { foo: [ "bar", "quuux" ], moo: [ "cow" ] },
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},
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{
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label: "Removed keys in new set show up",
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src_data: { foo: [ "bar" ] },
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dest_data: {},
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expected: { foo: null },
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},
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{
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label: "Indexes after a null terminator aren't included",
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src_data: { foo: [ "one", "two", "three", "four" ] },
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dest_data: { foo: [ "one", "done" ] },
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expected: { foo: [ undefined, "done", null ] },
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},
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{
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label: "Consider nested arrays to be scalar values",
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src_data: { foo: [ [ "one" ], [ "two", "three" ] ] },
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dest_data: { foo: [ [ "one" ], [ "two" ] ] },
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expected: { foo: [ undefined, [ "two" ] ] },
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},
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{
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label: "Don't evaluate zeros as falsy",
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src_data: { foo: [ 0 ] },
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dest_data: { foo: [ 0 ] },
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expected: {},
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},
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{
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label: "Don't evaluate empty strings as falsy",
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src_data: { foo: [ '' ] },
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dest_data: { foo: [ '' ] },
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expected: {},
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},
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] ).forEach( ( { label, src_data, dest_data, expected } ) =>
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{
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it( label, () =>
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{
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expect( sut( src_data, dest_data ) ).to.deep.equal( expected );
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} );
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} );
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} );
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