diff --git a/java/proguard.flags b/java/proguard.flags
index ca205b9..376a0e0 100644
--- a/java/proguard.flags
+++ b/java/proguard.flags
@@ -20,6 +20,10 @@
   boolean equalsIgnoreCase(...);
 }
 
+-keep class com.android.inputmethod.latin.InputPointers {
+  *;
+}
+
 -keep class com.android.inputmethod.latin.spellcheck.SpellCheckerSettingsFragment {
   *;
 }
diff --git a/java/src/com/android/inputmethod/latin/InputPointers.java b/java/src/com/android/inputmethod/latin/InputPointers.java
index 9d77d4e..cd53bcd 100644
--- a/java/src/com/android/inputmethod/latin/InputPointers.java
+++ b/java/src/com/android/inputmethod/latin/InputPointers.java
@@ -16,9 +16,6 @@
 
 package com.android.inputmethod.latin;
 
-import java.util.Arrays;
-
-// TODO: Add unit test
 public class InputPointers {
     private final ScalableIntArray mXCoordinates = new ScalableIntArray();
     private final ScalableIntArray mYCoordinates = new ScalableIntArray();
@@ -118,9 +115,10 @@
         }
 
         public void add(int val) {
-            ensureCapacity(mLength);
+            final int nextLength = mLength + 1;
+            ensureCapacity(nextLength);
             mArray[mLength] = val;
-            ++mLength;
+            mLength = nextLength;
         }
 
         public void ensureCapacity(int minimumCapacity) {
@@ -132,7 +130,7 @@
 
         private void grow(int newCapacity) {
             final int[] newArray = new int[newCapacity];
-            System.arraycopy(mArray, 0, newArray, 0, mLength);
+            System.arraycopy(mArray, 0, newArray, 0, mArray.length);
             mArray = newArray;
         }
 
@@ -150,7 +148,8 @@
         }
 
         public void copy(ScalableIntArray ip) {
-            mArray = Arrays.copyOf(ip.mArray, ip.mArray.length);
+            ensureCapacity(ip.mLength);
+            System.arraycopy(ip.mArray, 0, mArray, 0, ip.mLength);
             mLength = ip.mLength;
         }
 
diff --git a/tests/src/com/android/inputmethod/latin/InputPointersTests.java b/tests/src/com/android/inputmethod/latin/InputPointersTests.java
new file mode 100644
index 0000000..b60c2df
--- /dev/null
+++ b/tests/src/com/android/inputmethod/latin/InputPointersTests.java
@@ -0,0 +1,173 @@
+/*
+ * Copyright (C) 2012 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.inputmethod.latin;
+
+import android.test.AndroidTestCase;
+
+public class InputPointersTests extends AndroidTestCase {
+    public void testNewInstance() {
+        final InputPointers src = new InputPointers();
+        assertEquals("newInstance size", 0, src.getPointerSize());
+        assertNotNull("new instance xCoordinates", src.getXCoordinates());
+        assertNotNull("new instance yCoordinates", src.getYCoordinates());
+        assertNotNull("new instance pointerIds", src.getPointerIds());
+        assertNotNull("new instance times", src.getTimes());
+    }
+
+    public void testReset() {
+        final InputPointers src = new InputPointers();
+        final int[] xCoordinates = src.getXCoordinates();
+        final int[] yCoordinates = src.getXCoordinates();
+        final int[] pointerIds = src.getXCoordinates();
+        final int[] times = src.getXCoordinates();
+
+        src.reset();
+        assertEquals("after reset size", 0, src.getPointerSize());
+        assertNotSame("after reset xCoordinates", xCoordinates, src.getXCoordinates());
+        assertNotSame("after reset yCoordinates", yCoordinates, src.getYCoordinates());
+        assertNotSame("after reset pointerIds", pointerIds, src.getPointerIds());
+        assertNotSame("after reset times", times, src.getTimes());
+    }
+
+    public void testAdd() {
+        final InputPointers src = new InputPointers();
+        final int limit = src.getXCoordinates().length * 2 + 10;
+        for (int i = 0; i < limit; i++) {
+            src.addPointer(i, i * 2, i * 3, i * 4);
+            assertEquals("after add " + i, i + 1, src.getPointerSize());
+        }
+        for (int i = 0; i < limit; i++) {
+            assertEquals("xCoordinates at " + i, i, src.getXCoordinates()[i]);
+            assertEquals("yCoordinates at " + i, i * 2, src.getYCoordinates()[i]);
+            assertEquals("pointerIds at " + i, i * 3, src.getPointerIds()[i]);
+            assertEquals("times at " + i, i * 4, src.getTimes()[i]);
+        }
+    }
+
+    public void testAddAt() {
+        final InputPointers src = new InputPointers();
+        final int limit = 1000, step = 100;
+        for (int i = 0; i < limit; i += step) {
+            src.addPointer(i, i, i * 2, i * 3, i * 4);
+            assertEquals("after add at " + i, i + 1, src.getPointerSize());
+        }
+        for (int i = 0; i < limit; i += step) {
+            assertEquals("xCoordinates at " + i, i, src.getXCoordinates()[i]);
+            assertEquals("yCoordinates at " + i, i * 2, src.getYCoordinates()[i]);
+            assertEquals("pointerIds at " + i, i * 3, src.getPointerIds()[i]);
+            assertEquals("times at " + i, i * 4, src.getTimes()[i]);
+        }
+    }
+
+    public void testSet() {
+        final InputPointers src = new InputPointers();
+        final int limit = src.getXCoordinates().length * 2 + 10;
+        for (int i = 0; i < limit; i++) {
+            src.addPointer(i, i * 2, i * 3, i * 4);
+        }
+        final InputPointers dst = new InputPointers();
+        dst.set(src);
+        assertEquals("after set size", dst.getPointerSize(), src.getPointerSize());
+        assertSame("after set xCoordinates", dst.getXCoordinates(), src.getXCoordinates());
+        assertSame("after set yCoordinates", dst.getYCoordinates(), src.getYCoordinates());
+        assertSame("after set pointerIds", dst.getPointerIds(), src.getPointerIds());
+        assertSame("after set times", dst.getTimes(), src.getTimes());
+    }
+
+    public void testCopy() {
+        final InputPointers src = new InputPointers();
+        final int limit = 100;
+        for (int i = 0; i < limit; i++) {
+            src.addPointer(i, i * 2, i * 3, i * 4);
+        }
+        final InputPointers dst = new InputPointers();
+        dst.copy(src);
+        assertEquals("after copy size", dst.getPointerSize(), src.getPointerSize());
+        assertNotSame("after copy xCoordinates", dst.getXCoordinates(), src.getXCoordinates());
+        assertNotSame("after copy yCoordinates", dst.getYCoordinates(), src.getYCoordinates());
+        assertNotSame("after copy pointerIds", dst.getPointerIds(), src.getPointerIds());
+        assertNotSame("after copy times", dst.getTimes(), src.getTimes());
+        final int size = dst.getPointerSize();
+        assertArrayEquals("after copy xCoordinates values",
+                dst.getXCoordinates(), 0, src.getXCoordinates(), 0, size);
+        assertArrayEquals("after copy yCoordinates values",
+                dst.getYCoordinates(), 0, src.getYCoordinates(), 0, size);
+        assertArrayEquals("after copy pointerIds values",
+                dst.getPointerIds(), 0, src.getPointerIds(), 0, size);
+        assertArrayEquals("after copy times values",
+                dst.getTimes(), 0, src.getTimes(), 0, size);
+    }
+
+    public void testAppend() {
+        final InputPointers src = new InputPointers();
+        final int limit = 100;
+        for (int i = 0; i < limit; i++) {
+            src.addPointer(i, i * 2, i * 3, i * 4);
+        }
+        final InputPointers dst = new InputPointers();
+        for (int i = 0; i < limit; i++) {
+            final int value = limit - i;
+            dst.addPointer(value * 4, value * 3, value * 2, value);
+        }
+        final InputPointers dstCopy = new InputPointers();
+        dstCopy.copy(dst);
+
+        dst.append(src, 0, 0);
+        assertEquals("after append zero size", limit, dst.getPointerSize());
+        assertArrayEquals("affer append zero xCoordinates", dstCopy.getXCoordinates(), 0,
+                dst.getXCoordinates(), 0, limit);
+        assertArrayEquals("affer append zero yCoordinates", dstCopy.getYCoordinates(), 0,
+                dst.getYCoordinates(), 0, limit);
+        assertArrayEquals("affer append zero pointerIds", dstCopy.getPointerIds(), 0,
+                dst.getPointerIds(), 0, limit);
+        assertArrayEquals("affer append zero times", dstCopy.getTimes(), 0,
+                dst.getTimes(), 0, limit);
+
+        dst.append(src, 0, src.getPointerSize());
+        assertEquals("after append size", limit * 2, dst.getPointerSize() + src.getPointerSize());
+        assertArrayEquals("affer append xCoordinates", dstCopy.getXCoordinates(), 0,
+                dst.getXCoordinates(), 0, limit);
+        assertArrayEquals("affer append yCoordinates", dstCopy.getYCoordinates(), 0,
+                dst.getYCoordinates(), 0, limit);
+        assertArrayEquals("affer append pointerIds", dstCopy.getPointerIds(), 0,
+                dst.getPointerIds(), 0, limit);
+        assertArrayEquals("affer append times", dstCopy.getTimes(), 0,
+                dst.getTimes(), 0, limit);
+        assertArrayEquals("after append xCoordinates", dst.getXCoordinates(), limit,
+                src.getXCoordinates(), 0, limit);
+        assertArrayEquals("after append yCoordinates", dst.getYCoordinates(), limit,
+                src.getYCoordinates(), 0, limit);
+        assertArrayEquals("after append pointerIds", dst.getPointerIds(), limit,
+                src.getPointerIds(), 0, limit);
+        assertArrayEquals("after append times", dst.getTimes(), limit,
+                src.getTimes(), 0, limit);
+    }
+
+    private static void assertArrayEquals(String message, int[] expecteds, int expectedPos,
+            int[] actuals, int actualPos, int length) {
+        if (expecteds == null && actuals == null) {
+            return;
+        }
+        if (expecteds == null || actuals == null) {
+            fail(message + ": expecteds=" + expecteds + " actuals=" + actuals);
+        }
+        for (int i = 0; i < length; i++) {
+            assertEquals(message + ": element at " + i,
+                    expecteds[i + expectedPos], actuals[i + actualPos]);
+        }
+    }
+}