fix(analytics): apply an opt-in change to the running session

The Settings switch is a plain SwitchPreferenceCompat, so it writes the preference itself. The GA client's 'enabled' flag is fixed when the client is built, so that write had no effect until the next launch. Rebuild the client when the preference changes from anywhere.

Author: criticalAY

AnkiDroid/src/main/java/com/ichi2/anki/analytics/AnkiDroidUsageAnalytics.kt

@@ -70,8 +70,18 @@ object AnkiDroidUsageAnalytics {
     private val sharedPrefsListener =
         SharedPreferences.OnSharedPreferenceChangeListener { prefs, key ->
             if (key == ANALYTICS_OPTIN_KEY) {
-                optIn = prefs.getBoolean(key, false)
-                Timber.i("Setting analytics opt-in to: %b", optIn)
+                val newOptIn = prefs.getBoolean(key, false)
+                // [isEnabled] updates `optIn` before it writes, so an unchanged value
+                // means it's already handling this toggle: don't rebuild twice
+                if (newOptIn != optIn) {
+                    optIn = newOptIn
+                    Timber.i("Setting analytics opt-in to: %b", optIn)
+                    // the client's `enabled` flag is fixed when it's built, so writes
+                    // from elsewhere (the Settings switch) need a rebuild to take effect
+                    if (::analyticsContext.isInitialized) {
+                        reinitialize(analyticsContext)
+                    }
+                }
             }
         }
 

AnkiDroid/src/test/java/com/ichi2/anki/analytics/AnkiDroidUsageAnalyticsTest.kt

@@ -3,11 +3,16 @@
 
 package com.ichi2.anki.analytics
 
+import androidx.core.content.edit
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.ichi2.anki.EmptyApplicationCategory
 import com.ichi2.anki.R
 import com.ichi2.anki.RobolectricTest
 import com.ichi2.testutils.EmptyApplication
+import io.mockk.every
+import io.mockk.mockkObject
+import io.mockk.unmockkObject
+import io.mockk.verify
 import org.hamcrest.CoreMatchers.equalTo
 import org.hamcrest.MatcherAssert.assertThat
 import org.junit.Test
@@ -38,4 +43,42 @@ class AnkiDroidUsageAnalyticsTest : RobolectricTest() {
     fun `analytics is disabled by default`() {
         assertThat(getPreferences().getBoolean(AnkiDroidUsageAnalytics.ANALYTICS_OPTIN_KEY, false), equalTo(false))
     }
+
+    @Test
+    fun `a preference write from elsewhere rebuilds the client`() {
+        withStubbedRebuild {
+            getPreferences().edit(commit = true) { putBoolean(AnkiDroidUsageAnalytics.ANALYTICS_OPTIN_KEY, true) }
+
+            assertThat(AnkiDroidUsageAnalytics.isEnabled, equalTo(true))
+            verify(exactly = 1) { AnkiDroidUsageAnalytics.reinitialize(any()) }
+        }
+    }
+
+    @Test
+    fun `a write that leaves the value unchanged does not rebuild the client`() {
+        withStubbedRebuild {
+            getPreferences().edit(commit = true) { putBoolean(AnkiDroidUsageAnalytics.ANALYTICS_OPTIN_KEY, false) }
+
+            verify(exactly = 0) { AnkiDroidUsageAnalytics.reinitialize(any()) }
+        }
+    }
+
+    /**
+     * Runs [block] with the analytics listener registered and `reinitialize` stubbed out:
+     * the real one rebuilds on [kotlinx.coroutines.Dispatchers.IO] and would outlive the test.
+     */
+    private fun withStubbedRebuild(block: () -> Unit) {
+        mockkObject(AnkiDroidUsageAnalytics)
+        every { AnkiDroidUsageAnalytics.reinitialize(any()) } returns Unit
+        try {
+            AnkiDroidUsageAnalytics.initialize(targetContext)
+            block()
+        } finally {
+            // clear the preference before unmocking, so the resulting change
+            // doesn't reach the real `reinitialize`
+            getPreferences().edit(commit = true) { remove(AnkiDroidUsageAnalytics.ANALYTICS_OPTIN_KEY) }
+            unmockkObject(AnkiDroidUsageAnalytics)
+            AnalyticsExceptionHandler.uninstall()
+        }
+    }
 }