Closes #5678: Selected session may render in ExternalAppBrowserActivity

app/src/main/java/org/mozilla/fenix/HomeActivity.kt

@@ -17,6 +17,7 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.widget.Toolbar
 import androidx.lifecycle.lifecycleScope
 import androidx.navigation.NavDestination
+import androidx.navigation.NavDirections
 import androidx.navigation.fragment.NavHostFragment
 import androidx.navigation.ui.AppBarConfiguration
 import androidx.navigation.ui.NavigationUI
@@ -247,14 +248,15 @@ open class HomeActivity : AppCompatActivity() {
         if (navHost.navController.alreadyOnDestination(R.id.browserFragment)) return
         @IdRes val fragmentId = if (from.fragmentId != 0) from.fragmentId else null
         val directions = getNavDirections(from, customTabSessionId)
-
-        navHost.navController.nav(fragmentId, directions)
+        if (directions != null) {
+            navHost.navController.nav(fragmentId, directions)
+        }
     }
 
     protected open fun getNavDirections(
         from: BrowserDirection,
         customTabSessionId: String?
-    ) = when (from) {
+    ): NavDirections? = when (from) {
         BrowserDirection.FromGlobal ->
             NavGraphDirections.actionGlobalBrowser(customTabSessionId)
         BrowserDirection.FromHome ->

app/src/main/java/org/mozilla/fenix/customtabs/ExternalAppBrowserActivity.kt

@@ -39,7 +39,12 @@ open class ExternalAppBrowserActivity : HomeActivity() {
     override fun getNavDirections(
         from: BrowserDirection,
         customTabSessionId: String?
-    ): NavDirections {
+    ): NavDirections? {
+        if (customTabSessionId == null) {
+            finish()
+            return null
+        }
+
         val manifest = intent
             .getWebAppManifest()
             ?.let { WebAppManifestParser().serialize(it).toString() }

app/src/test/java/org/mozilla/fenix/customtabs/ExternalAppBrowserActivityTest.kt

@@ -5,10 +5,20 @@
 package org.mozilla.fenix.customtabs
 
 import android.content.Intent
+import android.os.Bundle
+import androidx.navigation.NavDirections
+import io.mockk.every
+import io.mockk.mockk
 import mozilla.components.support.utils.toSafeIntent
 import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertNull
 import org.junit.Test
 import org.junit.runner.RunWith
+import org.mockito.Mockito.never
+import org.mockito.Mockito.spy
+import org.mockito.Mockito.verify
+import org.mozilla.fenix.BrowserDirection
 import org.mozilla.fenix.TestApplication
 import org.mozilla.fenix.components.metrics.Event
 import org.robolectric.RobolectricTestRunner
@@ -33,4 +43,32 @@ class ExternalAppBrowserActivityTest {
         val otherIntent = Intent().toSafeIntent()
         assertEquals(Event.OpenedApp.Source.CUSTOM_TAB, activity.getIntentSource(otherIntent))
     }
+
+    @Test
+    fun `getNavDirections finishes activity if session ID is null`() {
+        val activity = spy(object : ExternalAppBrowserActivity() {
+            public override fun getNavDirections(
+                from: BrowserDirection,
+                customTabSessionId: String?
+            ): NavDirections? {
+                return super.getNavDirections(from, customTabSessionId)
+            }
+
+            override fun getIntent(): Intent {
+                val intent: Intent = mockk()
+                val bundle: Bundle = mockk()
+                every { bundle.getString(any()) } returns ""
+                every { intent.extras } returns bundle
+                return intent
+            }
+        })
+
+        var directions = activity.getNavDirections(BrowserDirection.FromGlobal, "id")
+        assertNotNull(directions)
+        verify(activity, never()).finish()
+
+        directions = activity.getNavDirections(BrowserDirection.FromGlobal, null)
+        assertNull(directions)
+        verify(activity).finish()
+    }
 }