diff --git a/app/src/main/java/org/mozilla/fenix/session/NotificationSessionObserver.kt b/app/src/main/java/org/mozilla/fenix/session/NotificationSessionObserver.kt
index 0826e4ac7..2df2cdb88 100644
--- a/app/src/main/java/org/mozilla/fenix/session/NotificationSessionObserver.kt
+++ b/app/src/main/java/org/mozilla/fenix/session/NotificationSessionObserver.kt
@@ -16,26 +16,27 @@ import org.mozilla.fenix.ext.sessionsOfType
  */
 
 class NotificationSessionObserver(
-    private val context: Context
+    private val context: Context,
+    private val notificationService: SessionNotificationService.Companion = SessionNotificationService
 ) : SessionManager.Observer {
 
     override fun onSessionRemoved(session: Session) {
         val privateTabsEmpty = context.components.core.sessionManager.sessionsOfType(private = true).none()
 
         if (privateTabsEmpty) {
-            SessionNotificationService.stop(context)
+            notificationService.stop(context)
         }
     }
 
     override fun onAllSessionsRemoved() {
-        SessionNotificationService.stop(context)
+        notificationService.stop(context)
     }
 
     override fun onSessionAdded(session: Session) {
         // Custom tabs are meant to feel like part of the app that opened them, not Fenix, so we
         // don't need to show a 'close tab' notification for them
         if (session.private && !session.isCustomTabSession()) {
-            SessionNotificationService.start(context)
+            notificationService.start(context)
         }
     }
 }
diff --git a/app/src/test/java/org/mozilla/fenix/session/NotificationSessionObserverTest.kt b/app/src/test/java/org/mozilla/fenix/session/NotificationSessionObserverTest.kt
new file mode 100644
index 000000000..ba0424bdd
--- /dev/null
+++ b/app/src/test/java/org/mozilla/fenix/session/NotificationSessionObserverTest.kt
@@ -0,0 +1,66 @@
+package org.mozilla.fenix.session
+
+import io.mockk.MockKAnnotations
+import io.mockk.every
+import io.mockk.impl.annotations.MockK
+import io.mockk.mockk
+import io.mockk.verify
+import mozilla.components.support.test.robolectric.testContext
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mozilla.fenix.TestApplication
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+import mozilla.components.browser.session.Session
+
+@RunWith(RobolectricTestRunner::class)
+@Config(application = TestApplication::class)
+class NotificationSessionObserverTest {
+
+    private lateinit var observer: NotificationSessionObserver
+    @MockK(relaxed = true) private lateinit var notificationService: SessionNotificationService.Companion
+
+    @Before
+    fun before() {
+        MockKAnnotations.init(this)
+        observer = NotificationSessionObserver(testContext, notificationService)
+    }
+
+    @Test
+    fun `GIVEN session is private and non-custom WHEN it is added THEN notification service should be started`() {
+        val privateSession = mockSession(true, false)
+
+        observer.onSessionAdded(privateSession)
+        verify(exactly = 1) { notificationService.start(any()) }
+    }
+
+    @Test
+    fun `GIVEN session is not private WHEN it is added THEN notification service should not be started`() {
+        val normalSession = mockSession(false, true)
+        val customSession = mockSession(false, false)
+
+        observer.onSessionAdded(normalSession)
+        verify(exactly = 0) { notificationService.start(any()) }
+
+        observer.onSessionAdded(customSession)
+        verify(exactly = 0) { notificationService.start(any()) }
+    }
+
+    @Test
+    fun `GIVEN session is custom tab WHEN it is added THEN notification service should not be started`() {
+        val privateCustomSession = mockSession(true, true)
+        val customSession = mockSession(false, true)
+
+        observer.onSessionAdded(privateCustomSession)
+        verify(exactly = 0) { notificationService.start(any()) }
+
+        observer.onSessionAdded(customSession)
+        verify(exactly = 0) { notificationService.start(any()) }
+    }
+}
+
+private fun mockSession(isPrivate: Boolean, isCustom: Boolean) = mockk<Session> {
+    every { private } returns isPrivate
+    every { isCustomTabSession() } returns isCustom
+}