// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package org.chromium.base;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.robolectric.annotation.Config;
import org.robolectric.annotation.LooperMode;
import org.robolectric.shadows.ShadowLooper;
import org.chromium.base.Promise.UnhandledRejectionException;
import org.chromium.base.test.BaseRobolectricTestRunner;
import java.util.function.Function;
/** Unit tests for {@link Promise}. */
@RunWith(BaseRobolectricTestRunner.class)
@Config(manifest = Config.NONE)
@LooperMode(LooperMode.Mode.LEGACY)
public class PromiseTest {
// We need a simple mutable reference type for testing.
private static class Value {
private int mValue;
public int get() {
return mValue;
}
public void set(int value) {
mValue = value;
}
}
/** Tests that the callback is called on fulfillment. */
@Test
public void callback() {
final Value value = new Value();
Promise<Integer> promise = new Promise<>();
promise.then(PromiseTest.setValue(value, 1));
assertEquals(value.get(), 0);
promise.fulfill(1);
assertEquals(value.get(), 1);
}
/** Tests that multiple callbacks are called. */
@Test
public void multipleCallbacks() {
final Value value = new Value();
Promise<Integer> promise = new Promise<>();
Callback<Integer> callback =
unusedArg -> {
value.set(value.get() + 1);
};
promise.then(callback);
promise.then(callback);
assertEquals(value.get(), 0);
promise.fulfill(0);
assertEquals(value.get(), 2);
}
/** Tests that a callback is called immediately when given to a fulfilled Promise. */
@Test
public void callbackOnFulfilled() {
final Value value = new Value();
Promise<Integer> promise = Promise.fulfilled(0);
assertEquals(value.get(), 0);
promise.then(PromiseTest.setValue(value, 1));
assertEquals(value.get(), 1);
}
/** Tests that promises can chain synchronous functions correctly. */
@Test
public void promiseChaining() {
Promise<Integer> promise = new Promise<>();
final Value value = new Value();
promise.then((Integer arg) -> arg.toString())
.then((String arg) -> arg + arg)
.then(
result -> {
value.set(result.length());
});
promise.fulfill(123);
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
assertEquals(6, value.get());
}
/** Tests that promises can chain asynchronous functions correctly. */
@Test
public void promiseChainingAsyncFunctions() {
Promise<Integer> promise = new Promise<>();
final Value value = new Value();
final Promise<String> innerPromise = new Promise<>();
promise.then(arg -> innerPromise)
.then(
result -> {
value.set(result.length());
});
assertEquals(0, value.get());
promise.fulfill(5);
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
assertEquals(0, value.get());
innerPromise.fulfill("abc");
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
assertEquals(3, value.get());
}
/** Tests that a Promise that does not use its result does not throw on rejection. */
@Test
public void rejectPromiseNoCallbacks() {
Promise<Integer> promise = new Promise<>();
boolean caught = false;
try {
promise.reject();
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
} catch (UnhandledRejectionException e) {
caught = true;
}
assertFalse(caught);
}
/** Tests that a Promise that uses its result throws on rejection if it has no handler. */
@Test
public void rejectPromiseNoHandler() {
Promise<Integer> promise = new Promise<>();
promise.then(PromiseTest.identity()).then(PromiseTest.pass());
boolean caught = false;
try {
promise.reject();
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
} catch (UnhandledRejectionException e) {
caught = true;
}
assertTrue(caught);
}
/** Tests that a Promise that handles rejection does not throw on rejection. */
@Test
public void rejectPromiseHandled() {
Promise<Integer> promise = new Promise<>();
promise.then(PromiseTest.identity()).then(PromiseTest.pass(), PromiseTest.pass());
boolean caught = false;
try {
promise.reject();
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
} catch (UnhandledRejectionException e) {
caught = true;
}
assertFalse(caught);
}
/** Tests that rejections carry the exception information. */
@Test
public void rejectionInformation() {
Promise<Integer> promise = new Promise<>();
promise.then(PromiseTest.pass());
String message = "Promise Test";
try {
promise.reject(new NegativeArraySizeException(message));
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
fail();
} catch (UnhandledRejectionException e) {
assertTrue(e.getCause() instanceof NegativeArraySizeException);
assertEquals(e.getCause().getMessage(), message);
}
}
/** Tests that rejections propagate. */
@Test
public void rejectionChaining() {
final Value value = new Value();
Promise<Integer> promise = new Promise<>();
Promise<Integer> result = promise.then(PromiseTest.identity()).then(PromiseTest.identity());
result.then(PromiseTest.pass(), PromiseTest.setValue(value, 5));
promise.reject(new Exception());
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
assertEquals(value.get(), 5);
assertTrue(result.isRejected());
}
/** Tests that Promises get rejected if a Function throws. */
@Test
public void rejectOnThrow() {
Value value = new Value();
Promise<Integer> promise = new Promise<>();
promise.then(
(Function)
(unusedArg -> {
throw new IllegalArgumentException();
}))
.then(PromiseTest.pass(), PromiseTest.setValue(value, 5));
promise.fulfill(0);
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
assertEquals(value.get(), 5);
}
/** Tests that Promises get rejected if an AsyncFunction throws. */
@Test
public void rejectOnAsyncThrow() {
Value value = new Value();
Promise<Integer> promise = new Promise<>();
promise.then(
(Promise.AsyncFunction)
(unusedArg -> {
throw new IllegalArgumentException();
}))
.then(PromiseTest.pass(), PromiseTest.setValue(value, 5));
promise.fulfill(0);
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
assertEquals(value.get(), 5);
}
/** Tests that Promises get rejected if an AsyncFunction rejects. */
@Test
public void rejectOnAsyncReject() {
Value value = new Value();
Promise<Integer> promise = new Promise<>();
final Promise<Integer> inner = new Promise<>();
promise.then(unusedArg -> inner).then(PromiseTest.pass(), PromiseTest.setValue(value, 5));
promise.fulfill(0);
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
assertEquals(value.get(), 0);
inner.reject();
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
assertEquals(value.get(), 5);
}
@Test
public void andFinallyOnFulfill() {
Value value = new Value();
Promise<Integer> promise = new Promise<>();
promise.andFinally(() -> value.set(5));
assertEquals(0, value.get());
promise.fulfill(0);
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
assertEquals(5, value.get());
}
@Test
public void andFinallyOnReject() {
Value value = new Value();
Promise<Integer> promise = new Promise<>();
promise.andFinally(() -> value.set(5));
assertEquals(0, value.get());
promise.reject();
ShadowLooper.runUiThreadTasksIncludingDelayedTasks();
assertEquals(5, value.get());
}
@Test
public void andFinallyChainingFulfillment() {
Value value = new Value();
Promise<Integer> promise = new Promise<>();
Promise<Integer> chainedPromise =
promise.andFinally(() -> value.set(value.get() + 1))
.then(Object::toString)
.andFinally(() -> value.set(value.get() * 10))
.then(String::length);
assertEquals(0, value.get());
assertTrue(chainedPromise.isPending());
promise.fulfill(123);
assertTrue(chainedPromise.isFulfilled());
assertEquals(10, value.get());
assertEquals(3, chainedPromise.getResult().intValue());
}
@Test
public void andFinallyChainingRejection() {
Value value = new Value();
Promise<Integer> promise = new Promise<>();
Promise<Integer> chainedPromise =
promise.andFinally(() -> value.set(value.get() + 1))
.then(Object::toString)
.andFinally(() -> value.set(value.get() * 10))
.then(String::length);
assertEquals(0, value.get());
assertTrue(chainedPromise.isPending());
promise.reject();
assertEquals(10, value.get()); // Both `andFinally()` still run.
assertTrue(chainedPromise.isRejected());
}
/** Convenience method that returns a Callback that does nothing with its result. */
private static <T> Callback<T> pass() {
return unusedArg -> {};
}
/** Convenience method that returns a Function that just passes through its argument. */
private static <T> Function<T, T> identity() {
return argument -> argument;
}
/** Convenience method that returns a Callback that sets the given Value on execution. */
private static <T> Callback<T> setValue(final Value toSet, final int value) {
return unusedArg -> {
toSet.set(value);
};
}
}
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