New enter pip assertion

Rename previous assertion to "pip app always visible" and create a new one asserting that pip window becomes visible

Test: atest FlickerTests:com.android.wm.shell.flicker.pip
Bug: 167521701
Change-Id: I237c8369b58a766b60f4eb96b7dc465e86f96679

libs/WindowManager/Shell/tests/flicker/src/com/android/wm/shell/flicker/pip/EnterPipTest.kt

@@ -16,6 +16,7 @@
 
 package com.android.wm.shell.flicker.pip
 
+import android.platform.test.annotations.Postsubmit
 import android.platform.test.annotations.Presubmit
 import android.view.Surface
 import androidx.test.filters.FlakyTest
@@ -49,7 +50,7 @@ class EnterPipTest(testSpec: FlickerTestParameter) : PipTransition(testSpec) {
 
     @Presubmit
     @Test
-    fun pipWindowBecomesVisible() {
+    fun pipAppWindowAlwaysVisible() {
         testSpec.assertWm {
             this.showsAppWindow(pipApp.defaultWindowName)
         }
@@ -63,6 +64,16 @@ class EnterPipTest(testSpec: FlickerTestParameter) : PipTransition(testSpec) {
         }
     }
 
+    @Postsubmit
+    @Test
+    fun pipWindowBecomesVisible() {
+        testSpec.assertWm {
+            invoke("pipWindowIsNotVisible") { !it.wmState.hasPipWindow() }
+                .then()
+                .invoke("pipWindowIsVisible") { it.wmState.hasPipWindow() }
+        }
+    }
+
     @FlakyTest(bugId = 140855415)
     @Test
     override fun navBarLayerIsAlwaysVisible() = super.navBarLayerIsAlwaysVisible()