Ensure FAB is hidden for some Vault Screen states (#401)

app/src/main/java/com/x8bit/bitwarden/ui/vault/feature/vault/VaultScreen.kt

@@ -265,7 +265,7 @@ private fun VaultScreenScaffold(
         },
         floatingActionButton = {
             AnimatedVisibility(
-                visible = !accountMenuVisible,
+                visible = state.viewState.hasFab && !accountMenuVisible,
                 enter = scaleIn(),
                 exit = scaleOut(),
             ) {

app/src/main/java/com/x8bit/bitwarden/ui/vault/feature/vault/VaultViewModel.kt

@@ -304,17 +304,27 @@ data class VaultState(
     @Parcelize
     sealed class ViewState : Parcelable {
 
+        /**
+         * Determines whether or not the Floating Action Button (FAB) should be shown for the
+         * given state.
+         */
+        abstract val hasFab: Boolean
+
         /**
          * Loading state for the [VaultScreen], signifying that the content is being processed.
          */
         @Parcelize
-        data object Loading : ViewState()
+        data object Loading : ViewState() {
+            override val hasFab: Boolean get() = false
+        }
 
         /**
          * Represents a state where the [VaultScreen] has no items to display.
          */
         @Parcelize
-        data object NoItems : ViewState()
+        data object NoItems : ViewState() {
+            override val hasFab: Boolean get() = true
+        }
 
         /**
          * Represents a state where the [VaultScreen] is unable to display data due to an error
@@ -323,7 +333,9 @@ data class VaultState(
         @Parcelize
         data class Error(
             val message: Text,
-        ) : ViewState()
+        ) : ViewState() {
+            override val hasFab: Boolean get() = false
+        }
 
         /**
          * Content state for the [VaultScreen] showing the actual content or items.
@@ -349,7 +361,9 @@ data class VaultState(
             val noFolderItems: List<VaultItem>,
             val collectionItems: List<CollectionItem>,
             val trashItemsCount: Int,
-        ) : ViewState()
+        ) : ViewState() {
+            override val hasFab: Boolean get() = true
+        }
 
         /**
          * Represents a folder item with a name and item count.

app/src/test/java/com/x8bit/bitwarden/ui/vault/feature/vault/VaultScreenTest.kt

@@ -283,6 +283,25 @@ class VaultScreenTest : BaseComposeTest() {
         verify { viewModel.trySendAction(VaultAction.ExitConfirmationClick) }
     }
 
+    @Test
+    fun `floating action button should be shown or hidden according to the state`() {
+        val fabDescription = "Add item"
+
+        mutableStateFlow.update { it.copy(viewState = VaultState.ViewState.Loading) }
+        composeTestRule.onNodeWithContentDescription(fabDescription).assertDoesNotExist()
+
+        mutableStateFlow.update {
+            it.copy(viewState = VaultState.ViewState.Error("Error".asText()))
+        }
+        composeTestRule.onNodeWithContentDescription(fabDescription).assertDoesNotExist()
+
+        mutableStateFlow.update { it.copy(viewState = VaultState.ViewState.NoItems) }
+        composeTestRule.onNodeWithContentDescription(fabDescription).assertIsDisplayed()
+
+        mutableStateFlow.update { it.copy(viewState = DEFAULT_CONTENT_VIEW_STATE) }
+        composeTestRule.onNodeWithContentDescription(fabDescription).assertIsDisplayed()
+    }
+
     @Test
     fun `error dialog should be shown or hidden according to the state`() {
         val errorTitle = "Error title"