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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
import { assertEquals } from "../testing/asserts.ts";import { distinctBy } from "./distinct_by.ts";
function distinctByTest<I>(  array: Array<I>,  selector: (element: I) => unknown,  expected: Array<I>,  message?: string,) {  const actual = distinctBy(array, selector);  assertEquals(actual, expected, message);}
Deno.test({  name: "[collections/distinctBy] identities on empty array",  fn() {    distinctByTest(      [],      () => {},      [],    );  },});
Deno.test({  name: "[collections/distinctBy] gets head on noop selector",  fn() {    distinctByTest(      [25, "asdf", true],      () => {},      [25],    );  },});
Deno.test({  name:    "[collections/distinctBy] removes duplicates and preserves order on identity",  fn() {    distinctByTest(      [true, "asdf", 4, "asdf", true],      (it) => it,      [true, "asdf", 4],    );    distinctByTest(      [null, undefined, null, "foo", undefined],      (it) => it,      [null, undefined, "foo"],    );  },});
Deno.test({  name: "[collections/distinctBy] does not check for deep equality on identity",  fn() {    const objects = [{ foo: "bar" }, { foo: "bar" }];    distinctByTest(      objects,      (it) => it,      objects,    );
    const arrays = [[], []];    distinctByTest(      arrays,      (it) => it,      arrays,    );
    const nans = [NaN, NaN];    distinctByTest(      nans,      (it) => it,      [nans[0]],    );
    const noops = [() => {}, () => {}];    distinctByTest(      noops,      (it) => it,      noops,    );
    const sets = [new Set(), new Set()];    distinctByTest(      sets,      (it) => it,      sets,    );  },});
Deno.test({  name:    "[collections/distinctBy] distincts by selected value and preserves order",  fn() {    const kim = { name: "Kim", age: 22 };    const arthur = { name: "Arthur", age: 22 };    const anna = { name: "Anna", age: 48 };    const karl = { name: "Karl", age: 48 };    const people = [kim, arthur, anna, karl];
    distinctByTest(      people,      (it) => it.name.charAt(0),      [kim, arthur],    );    distinctByTest(      people,      (it) => it.age,      [kim, anna],    );    distinctByTest(      people,      (it) => it.name.length,      [kim, arthur, anna],    );  },});