Rewrite BatteryOptimizationsFragment to Compose

app/src/androidTest/kotlin/at/bitfire/davdroid/settings/SettingsManagerTest.kt

@@ -4,10 +4,17 @@
 
 package at.bitfire.davdroid.settings
 
+import at.bitfire.davdroid.TestUtils.getOrAwaitValue
 import dagger.hilt.android.testing.HiltAndroidRule
 import dagger.hilt.android.testing.HiltAndroidTest
+import kotlinx.coroutines.CompletableDeferred
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.runBlocking
+import org.junit.After
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
 import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
@@ -16,6 +23,12 @@ import javax.inject.Inject
 @HiltAndroidTest
 class SettingsManagerTest {
 
+    companion object {
+        /** Use this setting to test SettingsManager methods. Will be removed after every test run. */
+        const val SETTING_TEST = "test"
+    }
+
+
     @get:Rule
     val hiltRule = HiltAndroidRule(this)
 
@@ -26,16 +39,58 @@ class SettingsManagerTest {
         hiltRule.inject()
     }
 
+    @After
+    fun removeTestSetting() {
+        settingsManager.remove(SETTING_TEST)
+    }
+
 
     @Test
-    fun testContainsKey_NotExisting() {
+    fun test_containsKey_NotExisting() {
         assertFalse(settingsManager.containsKey("notExisting"))
     }
 
     @Test
-    fun testContainsKey_Existing() {
+    fun test_containsKey_Existing() {
         // provided by DefaultsProvider
         assertEquals(Settings.PROXY_TYPE_SYSTEM, settingsManager.getInt(Settings.PROXY_TYPE))
     }
 
+
+    @Test
+    fun test_getBooleanLive_getValue() = runBlocking(Dispatchers.Main) {    // observeForever can't be run in background thread
+        val live = settingsManager.getBooleanLive(SETTING_TEST)
+        assertNull(live.value)
+
+        // set value
+        settingsManager.putBoolean(SETTING_TEST, true)
+        assertTrue(live.getOrAwaitValue()!!)
+
+        // set another value
+        live.value = false
+        assertFalse(live.getOrAwaitValue()!!)
+    }
+
+
+    @Test
+    fun test_ObserverCalledWhenValueChanges() {
+        val value = CompletableDeferred<Int>()
+        val observer = SettingsManager.OnChangeListener {
+            value.complete(settingsManager.getInt(SETTING_TEST))
+        }
+
+        try {
+            settingsManager.addOnChangeListener(observer)
+            settingsManager.putInt(SETTING_TEST, 123)
+
+            runBlocking {
+                // wait until observer is called
+                assertEquals(123, value.await())
+            }
+
+        } finally {
+            settingsManager.removeOnChangeListener(observer)
+        }
+    }
+
 }

app/src/main/kotlin/at/bitfire/davdroid/settings/SettingsManager.kt

@@ -7,7 +7,9 @@ package at.bitfire.davdroid.settings
 import android.content.Context
 import android.util.NoSuchPropertyException
 import androidx.annotation.AnyThread
+import androidx.lifecycle.MutableLiveData
 import at.bitfire.davdroid.log.Logger
+import at.bitfire.davdroid.settings.SettingsManager.OnChangeListener
 import dagger.Module
 import dagger.Provides
 import dagger.hilt.EntryPoint
@@ -170,6 +172,38 @@ class SettingsManager internal constructor(
     fun remove(key: String) = putString(key, null)
 
 
+    /*** LIVE DATA ***/
+
+    /**
+     * Returns a [MutableLiveData] which is backed by the settings with the given key.
+     * An observer must be added to the returned [MutableLiveData] to make it active.
+     */
+    fun getBooleanLive(key: String) = object : MutableLiveData<Boolean?>() {
+        private val preferenceChangeListener = OnChangeListener { updateValue() }
+
+        private fun updateValue() {
+            value = getBooleanOrNull(key)
+        }
+
+        // setValue is also called from postValue, so no need to override
+        override fun setValue(value: Boolean?) {
+            super.setValue(value)
+            putBoolean(key, value)
+        }
+
+        override fun onActive() {
+            super.onActive()
+            updateValue()
+            addOnChangeListener(preferenceChangeListener)
+        }
+
+        override fun onInactive() {
+            super.onInactive()
+            removeOnChangeListener(preferenceChangeListener)
+        }
+    }
+
+
     /*** HELPERS ***/
 
     fun dump(writer: Writer) {
@@ -180,7 +214,7 @@ class SettingsManager internal constructor(
     }
 
 
-    interface OnChangeListener {
+    fun interface OnChangeListener {
         /**
          * Will be called when something has changed in a [SettingsProvider].
          * May run in worker thread!