/
distinct_by_test.ts
121 lines (109 loc) · 2.32 KB
/
distinct_by_test.ts
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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],
);
},
});