Implement single-selection mode for SelectionDelegate.

chrome/android/junit/src/org/chromium/chrome/browser/widget/selection/SelectionDelegateTest.java

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.widget.selection;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.annotation.Config;
+
+import org.chromium.testing.local.LocalRobolectricTestRunner;
+
+/**
+ * Tests for the {@link SelectionDelegate} class.
+ */
+@RunWith(LocalRobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public class SelectionDelegateTest {
+    private final Object mData1 = new Object();
+    private final Object mData2 = new Object();
+
+    @Test
+    public void testSelectionDelegateSingle() {
+        SelectionDelegate<Object> delegate = new SelectionDelegate<Object>();
+        delegate.setSingleSelectionMode();
+
+        // Starting state, nothing is selected.
+        assertFalse(delegate.isItemSelected(mData1));
+        assertFalse(delegate.isSelectionEnabled());
+
+        // Select first item and verify selection.
+        delegate.toggleSelectionForItem(mData1);
+        assertTrue(delegate.isItemSelected(mData1));
+        assertTrue(delegate.isSelectionEnabled());
+
+        // Select second item, first item gets unselected.
+        delegate.toggleSelectionForItem(mData2);
+        assertFalse(delegate.isItemSelected(mData1));
+        assertTrue(delegate.isItemSelected(mData2));
+        assertTrue(delegate.isSelectionEnabled());
+
+        // Unselect second item.
+        delegate.toggleSelectionForItem(mData2);
+        assertFalse(delegate.isItemSelected(mData2));
+        assertFalse(delegate.isSelectionEnabled());
+
+        // Test clearing selection.
+        delegate.toggleSelectionForItem(mData1);
+        delegate.clearSelection();
+        assertFalse(delegate.isItemSelected(mData2));
+        assertFalse(delegate.isSelectionEnabled());
+    }
+
+    @Test
+    public void testSelectionDelegateMulti() {
+        SelectionDelegate<Object> delegate = new SelectionDelegate<Object>();
+
+        // Starting state, nothing is selected.
+        assertFalse(delegate.isItemSelected(mData1));
+        assertFalse(delegate.isSelectionEnabled());
+
+        // Select first item and verify selection.
+        delegate.toggleSelectionForItem(mData1);
+        assertTrue(delegate.isItemSelected(mData1));
+        assertTrue(delegate.isSelectionEnabled());
+
+        // Select second item, first item does not get unselected.
+        delegate.toggleSelectionForItem(mData2);
+        assertTrue(delegate.isItemSelected(mData1));
+        assertTrue(delegate.isItemSelected(mData2));
+        assertTrue(delegate.isSelectionEnabled());
+
+        // Unselect second item.
+        delegate.toggleSelectionForItem(mData2);
+        assertFalse(delegate.isItemSelected(mData2));
+        assertTrue(delegate.isItemSelected(mData1));
+        assertTrue(delegate.isSelectionEnabled());
+
+        // Test clearing selection.
+        delegate.clearSelection();
+        assertFalse(delegate.isItemSelected(mData1));
+        assertFalse(delegate.isItemSelected(mData2));
+        assertFalse(delegate.isSelectionEnabled());
+    }
+}