RS Posts: Add unit tests for ViewModel and Tab (#22661)

* RS Posts: Add unit tests for PostRsListViewModel and PostRsListTab

Add basic test coverage for the experimental RS post list feature:
- PostRsListViewModelTest (31 tests): init state, search, author
  filter, open/create post, menu actions, pending confirmations,
  network checks, and isAuthorFilterSupported
- PostRsListTabTest (8 tests): tab statuses, sort order, uniqueness

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Fix empty line after brace warning

* RS Posts: Fix flaky ViewModel tests with StandardTestDispatcher

Use StandardTestDispatcher instead of UnconfinedTestDispatcher to
prevent initTab coroutines from dispatching to Dispatchers.IO and
racing against Dispatchers.resetMain() between tests.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: nbradbury

WordPress/src/test/java/org/wordpress/android/ui/postsrs/PostRsListTabTest.kt

@@ -0,0 +1,60 @@
+package org.wordpress.android.ui.postsrs
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.Test
+import uniffi.wp_api.PostStatus
+import uniffi.wp_api.WpApiParamOrder
+
+class PostRsListTabTest {
+    @Test
+    fun `PUBLISHED tab contains Publish and Private statuses`() {
+        assertThat(PostRsListTab.PUBLISHED.statuses)
+            .containsExactly(PostStatus.Publish, PostStatus.Private)
+    }
+
+    @Test
+    fun `DRAFTS tab contains Draft and Pending statuses`() {
+        assertThat(PostRsListTab.DRAFTS.statuses)
+            .containsExactly(PostStatus.Draft, PostStatus.Pending)
+    }
+
+    @Test
+    fun `SCHEDULED tab contains only Future status`() {
+        assertThat(PostRsListTab.SCHEDULED.statuses)
+            .containsExactly(PostStatus.Future)
+    }
+
+    @Test
+    fun `TRASHED tab contains only Trash status`() {
+        assertThat(PostRsListTab.TRASHED.statuses)
+            .containsExactly(PostStatus.Trash)
+    }
+
+    @Test
+    fun `SCHEDULED tab uses ascending order`() {
+        assertThat(PostRsListTab.SCHEDULED.order)
+            .isEqualTo(WpApiParamOrder.ASC)
+    }
+
+    @Test
+    fun `non-SCHEDULED tabs use descending order`() {
+        assertThat(PostRsListTab.PUBLISHED.order)
+            .isEqualTo(WpApiParamOrder.DESC)
+        assertThat(PostRsListTab.DRAFTS.order)
+            .isEqualTo(WpApiParamOrder.DESC)
+        assertThat(PostRsListTab.TRASHED.order)
+            .isEqualTo(WpApiParamOrder.DESC)
+    }
+
+    @Test
+    fun `all tabs have exactly four entries`() {
+        assertThat(PostRsListTab.entries).hasSize(4)
+    }
+
+    @Test
+    fun `all statuses across tabs are unique`() {
+        val allStatuses = PostRsListTab.entries
+            .flatMap { it.statuses }
+        assertThat(allStatuses).doesNotHaveDuplicates()
+    }
+}