Update unit test

Author: warmkesselj

PayPalWebPayments/src/main/java/com/paypal/android/paypalwebpayments/PayPalWebCheckoutClient.kt

@@ -48,7 +48,7 @@ class PayPalWebCheckoutClient internal constructor(
 
     private val activityReference = WeakReference(activity)
 
-    private var observer = PayPalWebCheckoutLifeCycleObserver(this)
+    internal var observer = PayPalWebCheckoutLifeCycleObserver(this)
 
     init {
         activity.lifecycle.addObserver(observer)

PayPalWebPayments/src/test/java/com/paypal/android/paypalwebpayments/PayPalWebCheckoutClientUnitTest.kt

@@ -6,15 +6,15 @@ import com.paypal.android.corepayments.CoreConfig
 import com.paypal.android.corepayments.PayPalSDKError
 import com.paypal.android.corepayments.analytics.AnalyticsService
 import io.mockk.*
-import junit.framework.TestCase.assertNotNull
-import junit.framework.TestCase.assertEquals
 import junit.framework.TestCase.assertSame
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.test.*
 import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.robolectric.RobolectricTestRunner
+import strikt.api.expectThat
+import strikt.assertions.isNull
 
 @ExperimentalCoroutinesApi
 @RunWith(RobolectricTestRunner::class)
@@ -209,13 +209,11 @@ class PayPalWebCheckoutClientUnitTest {
     fun `when client is complete, lifecycle observer is removed`() {
         val lifeCycle = mockk<Lifecycle>(relaxed = true)
         every { activity.lifecycle } returns lifeCycle
-        
-        assertNotNull(sut.listener)
-        assertNotNull(sut.vaultListener)
 
         sut.removeObservers()
 
-        assertEquals(sut.listener, null)
-        assertEquals(sut.vaultListener, null)
+        verify { lifeCycle.removeObserver(sut.observer) }
+        expectThat(sut.listener).isNull()
+        expectThat(sut.vaultListener).isNull()
     }
 }