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promise_test(async () => {
const results = [];
const source = new Observable(subscriber => {
subscriber.addTeardown(() => results.push('teardown'));
subscriber.next(1);
results.push(subscriber.active ? 'active' : 'inactive');
results.push(subscriber.signal.aborted ? 'aborted' : 'not aborted')
// Ignored.
subscriber.next(2);
subscriber.complete();
});
const value = await source.first();
assert_array_equals(results, ['teardown', 'inactive', 'aborted']);
assert_equals(value, 1,
"Promise resolves with the first value from the source Observable");
}, "first(): Promise resolves with the first value from the source Observable");
promise_test(async (t) => {
const error = new Error("error from source");
const source = new Observable(subscriber => {
subscriber.error(error);
});
return promise_rejects_exactly(t, error, source.first(), "Promise rejects with source Observable error");
}, "first(): Promise rejects with the error emitted from the source Observable");
promise_test(async (t) => {
const source = new Observable(subscriber => {
subscriber.complete();
});
return promise_rejects_js(t, RangeError, source.first(), "Upon complete(), first() Promise rejects with RangeError");
}, "first(): Promise rejects with RangeError when source Observable " +
"completes without emitting any values");
promise_test(async (t) => {
const source = new Observable(subscriber => {});
const controller = new AbortController();
const promise = source.first({ signal: controller.signal });
controller.abort();
return promise_rejects_dom(t, "AbortError", promise, "Promise rejects with a DOMException for abortion");
}, "first(): Aborting a signal rejects the Promise with an AbortError DOMException");
promise_test(async () => {
const results = [];
const source = new Observable(subscriber => {
results.push("source subscribe");
subscriber.addTeardown(() => results.push("source teardown"));
subscriber.signal.addEventListener("abort", () => results.push("source abort"));
results.push("before source next 1");
subscriber.next(1);
results.push("after source next 1");
});
results.push("calling first");
const promise = source.first();
assert_array_equals(results, [
"calling first",
"source subscribe",
"before source next 1",
"source abort",
"source teardown",
"after source next 1"
], "Array values after first() is called");
const firstValue = await promise;
results.push(`first resolved with: ${firstValue}`);
assert_array_equals(results, [
"calling first",
"source subscribe",
"before source next 1",
"source abort",
"source teardown",
"after source next 1",
"first resolved with: 1",
], "Array values after Promise is awaited");
}, "first(): Lifecycle");
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