Merge "Add LiveDataTestUtil"

packages/SettingsLib/Spa/testutils/src/com/android/settingslib/spa/testutils/LiveDataTestUtil.kt

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2022 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 com.android.settingslib.spa.testutils
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.Observer
+import java.util.concurrent.CountDownLatch
+import java.util.concurrent.TimeUnit
+import java.util.concurrent.TimeoutException
+
+fun <T> LiveData<T>.getOrAwaitValue(
+    timeout: Long = 1,
+    timeUnit: TimeUnit = TimeUnit.SECONDS,
+    afterObserve: () -> Unit = {},
+): T? {
+    var data: T? = null
+    val latch = CountDownLatch(1)
+    val observer = Observer<T> { newData ->
+        data = newData
+        latch.countDown()
+    }
+    this.observeForever(observer)
+
+    afterObserve()
+
+    try {
+        // Don't wait indefinitely if the LiveData is not set.
+        if (!latch.await(timeout, timeUnit)) {
+            throw TimeoutException("LiveData value was never set.")
+        }
+    } finally {
+        this.removeObserver(observer)
+    }
+
+    return data
+}