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promise_test(async () => {
let inactiveAfterB = false;
const source = new Observable(subscriber => {
subscriber.next("a");
subscriber.next("b");
inactiveAfterB = !subscriber.active;
subscriber.next("c");
subscriber.complete();
});
const value = await source.find((value) => value === "b");
assert_equals(value, "b", "Promise resolves with the first value that passes the predicate");
assert_true(inactiveAfterB, "subscriber is inactive after the first value that passes the predicate");
}, "find(): Promise resolves with the first value that passes the predicate");
promise_test(async () => {
const source = new Observable(subscriber => {
subscriber.next("a");
subscriber.next("b");
subscriber.next("c");
subscriber.complete();
});
const value = await source.find(() => false);
assert_equals(value, undefined, "Promise resolves with undefined if no value passes the predicate");
}, "find(): Promise resolves with undefined if no value passes the predicate");
promise_test(async t => {
const error = new Error("error from source");
const source = new Observable(subscriber => {
subscriber.error(error);
});
promise_rejects_exactly(t, error, source.find(() => true), "Promise " +
"rejects with the error emitted from the source Observable");
}, "find(): Promise rejects with the error emitted from the source Observable");
promise_test(async t => {
const source = new Observable(subscriber => {
subscriber.next("ignored");
});
const error = new Error("thrown from predicate");
promise_rejects_exactly(t, error, source.find(() => {throw error}),
"Promise rejects with any error thrown from the predicate");
}, "find(): Promise rejects with any error thrown from the predicate");
promise_test(async () => {
let indices = [];
const source = new Observable(subscriber => {
subscriber.next("a");
subscriber.next("b");
subscriber.next("c");
subscriber.complete();
});
const value = await source.find((value, index) => {
indices.push(index);
return false;
});
assert_equals(value, undefined, "Promise resolves with undefined if no value passes the predicate");
assert_array_equals(indices, [0, 1, 2], "find(): Passes the index of the value to the predicate");
}, "find(): Passes the index of the value to the predicate");
promise_test(async t => {
const controller = new AbortController();
const source = new Observable(subscriber => {
subscriber.next("a");
subscriber.next("b");
subscriber.next("c");
subscriber.complete();
});
controller.abort();
const promise = source.find(() => true, { signal: controller.signal });
promise_rejects_dom(t, 'AbortError', promise, "Promise rejects with " +
"DOMException when the signal is aborted");
}, "find(): Rejects with AbortError when the signal is aborted");
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