Added test cases for testing this functionality.

core/src/main/java/org/kiwix/kiwixmobile/core/main/CoreReaderFragment.kt

@@ -398,7 +398,7 @@ abstract class CoreReaderFragment :
   ) {
     super.onViewCreated(view, savedInstanceState)
     setupMenu()
-    donationDialogHandler?.showDonationDialogCallBack(this)
+    donationDialogHandler?.setDonationDialogCallBack(this)
     val activity = requireActivity() as AppCompatActivity?
     activity?.let {
       WebView(it).destroy() // Workaround for buggy webViews see #710
@@ -1224,7 +1224,7 @@ abstract class CoreReaderFragment :
     unRegisterReadAloudService()
     storagePermissionForNotesLauncher?.unregister()
     storagePermissionForNotesLauncher = null
-    donationDialogHandler?.showDonationDialogCallBack(null)
+    donationDialogHandler?.setDonationDialogCallBack(null)
     donationDialogHandler = null
   }
 

core/src/main/java/org/kiwix/kiwixmobile/core/utils/DonationDialogHandler.kt

@@ -34,7 +34,7 @@ class DonationDialogHandler @Inject constructor(
 
   private var showDonationDialogCallback: ShowDonationDialogCallback? = null
 
-  fun showDonationDialogCallBack(showDonationDialogCallback: ShowDonationDialogCallback?) {
+  fun setDonationDialogCallBack(showDonationDialogCallback: ShowDonationDialogCallback?) {
     this.showDonationDialogCallback = showDonationDialogCallback
   }
 
@@ -61,18 +61,18 @@ class DonationDialogHandler @Inject constructor(
     return timeDifference >= THREE_DAYS_IN_MILLISECONDS
   }
 
-  private fun isZimFilesAvailableInLibrary(): Boolean =
+  fun isZimFilesAvailableInLibrary(): Boolean =
     if (activity.isCustomApp()) true else newBookDao.getBooks().isNotEmpty()
 
   fun updateLastDonationPopupShownTime() {
     sharedPreferenceUtil.lastDonationPopupShownInMilliSeconds = System.currentTimeMillis()
   }
 
-  fun donateLater() {
-    sharedPreferenceUtil.laterClickedMilliSeconds = System.currentTimeMillis()
+  fun donateLater(currentMillis: Long = System.currentTimeMillis()) {
+    sharedPreferenceUtil.laterClickedMilliSeconds = currentMillis
   }
 
-  private fun resetDonateLater() {
+  fun resetDonateLater() {
     sharedPreferenceUtil.laterClickedMilliSeconds = 0L
   }
 

core/src/test/java/org/kiwix/kiwixmobile/core/utils/DonationDialogHandlerTest.kt

@@ -0,0 +1,127 @@
+/*
+ * Kiwix Android
+ * Copyright (c) 2024 Kiwix <android.kiwix.org>
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package org.kiwix.kiwixmobile.core.utils
+
+import android.app.Activity
+import io.mockk.Runs
+import io.mockk.every
+import io.mockk.just
+import io.mockk.mockk
+import io.mockk.verify
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.kiwix.kiwixmobile.core.dao.NewBookDao
+import org.kiwix.kiwixmobile.core.extensions.ActivityExtensions
+
+class DonationDialogHandlerTest {
+  private lateinit var activity: Activity
+  private lateinit var sharedPreferenceUtil: SharedPreferenceUtil
+  private lateinit var newBookDao: NewBookDao
+  private lateinit var donationDialogHandler: DonationDialogHandler
+  private lateinit var showDonationDialogCallback: DonationDialogHandler.ShowDonationDialogCallback
+
+  @BeforeEach
+  fun setup() {
+    activity = mockk(relaxed = true)
+    sharedPreferenceUtil = mockk(relaxed = true)
+    newBookDao = mockk(relaxed = true)
+    showDonationDialogCallback = mockk(relaxed = true)
+    donationDialogHandler = DonationDialogHandler(activity, sharedPreferenceUtil, newBookDao)
+    donationDialogHandler.setDonationDialogCallBack(showDonationDialogCallback)
+  }
+
+  @Test
+  fun `test should show initial popup`() {
+    every { sharedPreferenceUtil.lastDonationPopupShownInMilliSeconds } returns 0L
+    every { newBookDao.getBooks() } returns listOf(mockk())
+    donationDialogHandler.attemptToShowDonationPopup()
+    verify { showDonationDialogCallback.showDonationDialog() }
+  }
+
+  @Test
+  fun `test should not show popup when time difference is less than 3 months`() {
+    val currentMilliSeconds = System.currentTimeMillis()
+    every {
+      sharedPreferenceUtil.lastDonationPopupShownInMilliSeconds
+    } returns currentMilliSeconds - (THREE_MONTHS_IN_MILLISECONDS / 2)
+    every { newBookDao.getBooks() } returns listOf(mockk())
+    donationDialogHandler.attemptToShowDonationPopup()
+    verify(exactly = 0) { showDonationDialogCallback.showDonationDialog() }
+  }
+
+  @Test
+  fun `test should show popup when time difference is more than 3 months`() {
+    val currentMilliSeconds = System.currentTimeMillis()
+    every {
+      sharedPreferenceUtil.lastDonationPopupShownInMilliSeconds
+    } returns currentMilliSeconds - (THREE_MONTHS_IN_MILLISECONDS + 1000)
+    every { newBookDao.getBooks() } returns listOf(mockk())
+    donationDialogHandler.attemptToShowDonationPopup()
+    verify { showDonationDialogCallback.showDonationDialog() }
+  }
+
+  @Test
+  fun `test donate later saves the correct time`() {
+    val currentMilliSeconds = System.currentTimeMillis()
+    every { sharedPreferenceUtil.laterClickedMilliSeconds = any() } just Runs
+    donationDialogHandler.donateLater(currentMilliSeconds)
+    verify { sharedPreferenceUtil.laterClickedMilliSeconds = currentMilliSeconds }
+  }
+
+  @Test
+  fun `test reset donate later sets value to zero`() {
+    every { sharedPreferenceUtil.laterClickedMilliSeconds = 0L } just Runs
+    donationDialogHandler.resetDonateLater()
+    verify { sharedPreferenceUtil.laterClickedMilliSeconds = 0L }
+  }
+
+  @Test
+  fun `test isZimFilesAvailableInLibrary returns true when isCustomApp is true`() {
+    with(mockk<ActivityExtensions>()) {
+      every { activity.packageName } returns "org.kiwix.kiwixcustom"
+      every { activity.isCustomApp() } returns true
+      val result = donationDialogHandler.isZimFilesAvailableInLibrary()
+      assertTrue(result)
+    }
+  }
+
+  @Test
+  fun `test isZimFilesAvailableInLibrary returns false when no books and isCustomApp is false`() {
+    with(mockk<ActivityExtensions>()) {
+      every { activity.packageName } returns "org.kiwix.kiwixmobile"
+      every { activity.isCustomApp() } returns false
+      every { newBookDao.getBooks() } returns emptyList()
+      val result = donationDialogHandler.isZimFilesAvailableInLibrary()
+      assertFalse(result)
+    }
+  }
+
+  @Test
+  fun `isZimFilesAvailableInLibrary returns true when books available and isCustomApp is false`() {
+    with(mockk<ActivityExtensions>()) {
+      every { activity.packageName } returns "org.kiwix.kiwixmobile"
+      every { activity.isCustomApp() } returns false
+      every { newBookDao.getBooks() } returns listOf(mockk())
+      val result = donationDialogHandler.isZimFilesAvailableInLibrary()
+      assertTrue(result)
+    }
+  }
+}