69 lines
1.9 KiB
JavaScript
69 lines
1.9 KiB
JavaScript
test("length is 1", () => {
|
|
expect(Array.from).toHaveLength(1);
|
|
});
|
|
|
|
describe("normal behavior", () => {
|
|
test("empty array", () => {
|
|
var a = Array.from([]);
|
|
expect(a instanceof Array).toBeTrue();
|
|
expect(a).toHaveLength(0);
|
|
});
|
|
|
|
test("empty string", () => {
|
|
var a = Array.from("");
|
|
expect(a instanceof Array).toBeTrue();
|
|
expect(a).toHaveLength(0);
|
|
});
|
|
|
|
test("non-empty array", () => {
|
|
var a = Array.from([5, 8, 1]);
|
|
expect(a instanceof Array).toBeTrue();
|
|
expect(a).toHaveLength(3);
|
|
expect(a[0]).toBe(5);
|
|
expect(a[1]).toBe(8);
|
|
expect(a[2]).toBe(1);
|
|
});
|
|
|
|
test("non-empty string", () => {
|
|
var a = Array.from("what");
|
|
expect(a instanceof Array).toBeTrue();
|
|
expect(a).toHaveLength(4);
|
|
expect(a[0]).toBe("w");
|
|
expect(a[1]).toBe("h");
|
|
expect(a[2]).toBe("a");
|
|
expect(a[3]).toBe("t");
|
|
});
|
|
|
|
test("shallow array copy", () => {
|
|
var a = [1, 2, 3];
|
|
var b = Array.from([a]);
|
|
expect(b instanceof Array).toBeTrue();
|
|
expect(b).toHaveLength(1);
|
|
b[0][0] = 4;
|
|
expect(a[0]).toBe(4);
|
|
});
|
|
|
|
test("from iterator", () => {
|
|
function rangeIterator(begin, end) {
|
|
return {
|
|
[Symbol.iterator]() {
|
|
let value = begin - 1;
|
|
return {
|
|
next() {
|
|
if (value < end) {
|
|
value += 1;
|
|
}
|
|
return { value: value, done: value >= end };
|
|
},
|
|
};
|
|
},
|
|
};
|
|
}
|
|
|
|
var a = Array.from(rangeIterator(8, 10));
|
|
expect(a instanceof Array).toBeTrue();
|
|
expect(a).toHaveLength(2);
|
|
expect(a[0]).toBe(8);
|
|
expect(a[1]).toBe(9);
|
|
});
|
|
});
|