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LibJS: Implement Array.prototype.groupByToMap

This commit is contained in:
Luke Wilde 2022-01-05 00:30:51 +00:00 committed by Linus Groh
parent 48cc1c97d5
commit 0b9ea712be
5 changed files with 207 additions and 0 deletions

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@ -317,4 +317,28 @@ describe("ability to work with generic non-array objects", () => {
expect(result.false).toEqual(["foo", undefined, undefined]);
expect(result.true).toEqual(["bar", "baz"]);
});
test("groupByToMap", () => {
const visited = [];
const o = { length: 5, 0: "foo", 1: "bar", 3: "baz" };
const falseObject = { false: false };
const trueObject = { true: true };
const result = Array.prototype.groupByToMap.call(o, (value, _, object) => {
expect(object).toBe(o);
visited.push(value);
return value !== undefined
? value.startsWith("b")
? trueObject
: falseObject
: falseObject;
});
expect(visited).toEqual(["foo", "bar", undefined, "baz", undefined]);
expect(result).toBeInstanceOf(Map);
const falseResult = result.get(falseObject);
expect(falseResult).toEqual(["foo", undefined, undefined]);
const trueResult = result.get(trueObject);
expect(trueResult).toEqual(["bar", "baz"]);
});
});

View file

@ -0,0 +1,107 @@
test("length is 1", () => {
expect(Array.prototype.groupByToMap).toHaveLength(1);
});
describe("errors", () => {
test("callback must be a function", () => {
expect(() => {
[].groupByToMap(undefined);
}).toThrowWithMessage(TypeError, "undefined is not a function");
});
test("null or undefined this value", () => {
expect(() => {
Array.prototype.groupByToMap.call();
}).toThrowWithMessage(TypeError, "ToObject on null or undefined");
expect(() => {
Array.prototype.groupByToMap.call(undefined);
}).toThrowWithMessage(TypeError, "ToObject on null or undefined");
expect(() => {
Array.prototype.groupByToMap.call(null);
}).toThrowWithMessage(TypeError, "ToObject on null or undefined");
});
});
describe("normal behavior", () => {
test("basic functionality", () => {
const array = [1, 2, 3, 4, 5, 6];
const visited = [];
const trueObject = { true: true };
const falseObject = { false: false };
const firstResult = array.groupByToMap(value => {
visited.push(value);
return value % 2 === 0 ? trueObject : falseObject;
});
expect(visited).toEqual([1, 2, 3, 4, 5, 6]);
expect(firstResult).toBeInstanceOf(Map);
expect(firstResult.size).toBe(2);
expect(firstResult.get(trueObject)).toEqual([2, 4, 6]);
expect(firstResult.get(falseObject)).toEqual([1, 3, 5]);
const secondResult = array.groupByToMap((_, index) => {
return index < array.length / 2 ? trueObject : falseObject;
});
expect(secondResult).toBeInstanceOf(Map);
expect(secondResult.size).toBe(2);
expect(secondResult.get(trueObject)).toEqual([1, 2, 3]);
expect(secondResult.get(falseObject)).toEqual([4, 5, 6]);
const thisArg = [7, 8, 9, 10, 11, 12];
const thirdResult = array.groupByToMap(function (_, __, arrayVisited) {
expect(arrayVisited).toBe(array);
expect(this).toBe(thisArg);
}, thisArg);
expect(thirdResult).toBeInstanceOf(Map);
expect(thirdResult.size).toBe(1);
expect(thirdResult.get(undefined)).not.toBe(array);
expect(thirdResult.get(undefined)).not.toBe(thisArg);
expect(thirdResult.get(undefined)).toEqual(array);
});
test("is unscopable", () => {
expect(Array.prototype[Symbol.unscopables].groupByToMap).toBeTrue();
const array = [];
with (array) {
expect(() => {
groupByToMap;
}).toThrowWithMessage(ReferenceError, "'groupByToMap' is not defined");
}
});
test("never calls callback with empty array", () => {
var callbackCalled = 0;
const result = [].groupByToMap(() => {
callbackCalled++;
});
expect(result).toBeInstanceOf(Map);
expect(result.size).toBe(0);
expect(callbackCalled).toBe(0);
});
test("calls callback once for every item", () => {
var callbackCalled = 0;
const result = [1, 2, 3].groupByToMap(() => {
callbackCalled++;
});
expect(result).toBeInstanceOf(Map);
expect(result.size).toBe(1);
expect(result.get(undefined)).toEqual([1, 2, 3]);
expect(callbackCalled).toBe(3);
});
test("still returns a Map even if the global Map constructor was changed", () => {
globalThis.Map = null;
const result = [1, 2].groupByToMap(value => {
return value % 2 === 0;
});
expect(result.size).toBe(2);
expect(result.get(true)).toEqual([2]);
expect(result.get(false)).toEqual([1]);
});
});