[SetupWizardLib] Add tests for BottomScrollView

Test that BottomScrollView callbacks are called correctly.

Change-Id: Ia2e9e4149057b06794cdf85ba07c44efc0aec579

library/main/src/com/android/setupwizardlib/view/BottomScrollView.java

@@ -21,6 +21,8 @@ import android.util.AttributeSet;
 import android.view.View;
 import android.widget.ScrollView;
 
+import com.android.annotations.VisibleForTesting;
+
 /**
  * An extension of ScrollView that will invoke a listener callback when the ScrollView needs
  * scrolling, and when the ScrollView is being scrolled to the bottom. This is often used in Setup
@@ -60,13 +62,17 @@ public class BottomScrollView extends ScrollView {
         mListener = l;
     }
 
+    @VisibleForTesting
+    public int getScrollThreshold() {
+        return mScrollThreshold;
+    }
+
     @Override
     protected void onLayout(boolean changed, int l, int t, int r, int b) {
         super.onLayout(changed, l, t, r, b);
-        View child = getChildAt(0);
+        final View child = getChildAt(0);
         if (child != null) {
-            mScrollThreshold = Math.max(0, getChildAt(0).getHeight() - b + t
-                    - getPaddingBottom());
+            mScrollThreshold = Math.max(0, child.getMeasuredHeight() - b + t - getPaddingBottom());
         }
         if (b - t > 0) {
             // Post check scroll in the next run loop, so that the callback methods will be invoked

library/test/src/com/android/setupwizardlib/test/BottomScrollViewTest.java

@@ -0,0 +1,125 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.setupwizardlib.test;
+
+import android.content.Context;
+import android.test.AndroidTestCase;
+import android.test.suitebuilder.annotation.SmallTest;
+import android.view.View;
+
+import com.android.setupwizardlib.view.BottomScrollView;
+
+public class BottomScrollViewTest extends AndroidTestCase {
+
+    private TestBottomScrollListener mListener;
+
+    @Override
+    protected void setUp() throws Exception {
+        super.setUp();
+        mListener = new TestBottomScrollListener();
+    }
+
+    @SmallTest
+    public void testNoNeedScroll() {
+        createScrollView(20);
+        assertTrue("Scroll should not be required", mListener.scrolledToBottom);
+    }
+
+    @SmallTest
+    public void testNeedScroll() {
+        createScrollView(110);
+        assertFalse("Scroll should be required", mListener.scrolledToBottom);
+    }
+
+    @SmallTest
+    public void testScrollToBottom() {
+        final BottomScrollView bottomScrollView = createScrollView(110);
+
+        assertFalse("Scroll should be required", mListener.scrolledToBottom);
+
+        bottomScrollView.scrollTo(0, 10);
+        assertTrue("Should already be scrolled to bottom", mListener.scrolledToBottom);
+    }
+
+    @SmallTest
+    public void testScrollThreshold() {
+        final BottomScrollView bottomScrollView = createScrollView(110);
+        assertEquals("Scroll threshold should be 10", 10, bottomScrollView.getScrollThreshold());
+    }
+
+    private BottomScrollView createScrollView(final int childHeight) {
+        final BottomScrollView bottomScrollView = new TestBottomScrollView(getContext());
+        bottomScrollView.setBottomScrollListener(mListener);
+
+        final View child = new TestChildView(getContext(), childHeight);
+
+        child.measure(0, 0); // TestChildView's measured dimensions doesn't depend on the arguments
+        bottomScrollView.addView(child);
+        bottomScrollView.layout(0, 0, 100, 100);
+
+        return bottomScrollView;
+    }
+
+    private static class TestChildView extends View {
+
+        private static final int WIDTH = 10;
+        private int mHeight;
+
+        public TestChildView(Context context, int height) {
+            super(context);
+            mHeight = height;
+        }
+
+        @Override
+        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+            setMeasuredDimension(WIDTH, mHeight);
+        }
+
+        public void setHeight(int height) {
+            mHeight = height;
+        }
+    }
+
+    private static class TestBottomScrollView extends BottomScrollView {
+
+        public TestBottomScrollView(Context context) {
+            super(context);
+        }
+
+        @Override
+        public boolean post(Runnable action) {
+            // Post all runnables synchronously so that tests can check the callbacks.
+            action.run();
+            return true;
+        }
+    }
+
+    private static class TestBottomScrollListener implements BottomScrollView.BottomScrollListener {
+
+        boolean scrolledToBottom = true;
+
+        @Override
+        public void onScrolledToBottom() {
+            scrolledToBottom = true;
+        }
+
+        @Override
+        public void onRequiresScroll() {
+            scrolledToBottom = false;
+        }
+    }
+}