WindowLayoutInfoPublisherRule.kt
/*
* Copyright 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.window.testing.layout
import androidx.window.layout.WindowInfoTracker
import androidx.window.layout.WindowLayoutInfo
import kotlinx.coroutines.channels.BufferOverflow.DROP_OLDEST
import kotlinx.coroutines.flow.MutableSharedFlow
import org.junit.rules.TestRule
import org.junit.runner.Description
import org.junit.runners.model.Statement
/**
* A [TestRule] to help test consuming a stream of [WindowLayoutInfo] values.
* [WindowLayoutInfoPublisherRule] allows you to push through different [WindowLayoutInfo] values
* on demand.
*
* Here are some recommended testing scenarios.
*
* To test the scenario where no [WindowLayoutInfo] is ever emitted. Just set the rule as a
* standard rule.
*
* To test sending a generic feature build your own [WindowLayoutInfo] and publish it through the
* method [WindowLayoutInfoPublisherRule.overrideWindowLayoutInfo].
*
* Some helper methods are provided to test the following scenarios.
* <ul>
* <li>A fold in the middle and the dimension matches the shortest window dimension.</li>
* <li>A fold in the middle and the dimension matches the longest window dimension.</li>
* <li>A fold in the middle and has vertical orientation.</li>
* <li>A fold in the middle and has horizontal orientation.</li>
* </ul>
*/
public class WindowLayoutInfoPublisherRule() : TestRule {
private val flow = MutableSharedFlow<WindowLayoutInfo>(
extraBufferCapacity = 1,
onBufferOverflow = DROP_OLDEST
)
private val overrideServices = PublishWindowInfoTrackerDecorator(flow)
override fun apply(base: Statement, description: Description): Statement {
return object : Statement() {
override fun evaluate() {
WindowInfoTracker.overrideDecorator(overrideServices)
try {
base.evaluate()
} finally {
WindowInfoTracker.reset()
}
}
}
}
/**
* Send an arbitrary [WindowLayoutInfo] through
* [androidx.window.layout.WindowInfoTracker.windowLayoutInfo]. Each event is sent only once.
*/
public fun overrideWindowLayoutInfo(info: WindowLayoutInfo) {
flow.tryEmit(info)
}
}