diff --git a/src/com/android/settings/graph/UsageGraph.java b/src/com/android/settings/graph/UsageGraph.java
index 5a4a9cd..a39cb43 100644
--- a/src/com/android/settings/graph/UsageGraph.java
+++ b/src/com/android/settings/graph/UsageGraph.java
@@ -28,8 +28,8 @@
 import android.graphics.Path;
 import android.graphics.Shader.TileMode;
 import android.graphics.drawable.Drawable;
+import android.support.annotation.VisibleForTesting;
 import android.util.AttributeSet;
-import android.util.Log;
 import android.util.SparseIntArray;
 import android.util.TypedValue;
 import android.view.View;
@@ -93,7 +93,7 @@
         float dots = resources.getDimensionPixelSize(R.dimen.usage_graph_dot_size);
         float interval = resources.getDimensionPixelSize(R.dimen.usage_graph_dot_interval);
         mDottedPaint.setStrokeWidth(dots * 3);
-        mDottedPaint.setPathEffect(new DashPathEffect(new float[]{dots, interval}, 0));
+        mDottedPaint.setPathEffect(new DashPathEffect(new float[] {dots, interval}, 0));
         mDottedPaint.setColor(context.getColor(R.color.usage_graph_dots));
 
         TypedValue v = new TypedValue();
@@ -136,8 +136,8 @@
         addPathAndUpdate(points, mProjectedPaths, mLocalProjectedPaths);
     }
 
-    private void addPathAndUpdate(SparseIntArray points, SparseIntArray paths,
-            SparseIntArray localPaths) {
+    private void addPathAndUpdate(
+            SparseIntArray points, SparseIntArray paths, SparseIntArray localPaths) {
         final long startTime = System.currentTimeMillis();
         for (int i = 0, size = points.size(); i < size; i++) {
             paths.put(points.keyAt(i), points.valueAt(i));
@@ -170,41 +170,44 @@
         calculateLocalPaths(mProjectedPaths, mLocalProjectedPaths);
     }
 
-    private void calculateLocalPaths(SparseIntArray paths, SparseIntArray localPaths) {
+    @VisibleForTesting
+    void calculateLocalPaths(SparseIntArray paths, SparseIntArray localPaths) {
         final long startTime = System.currentTimeMillis();
         if (getWidth() == 0) {
             return;
         }
         localPaths.clear();
-        int pendingXLoc = 0;
-        int pendingYLoc = PATH_DELIM;
+        // Store the local coordinates of the most recent point.
+        int lx = 0;
+        int ly = PATH_DELIM;
+        boolean skippedLastPoint = false;
         for (int i = 0; i < paths.size(); i++) {
             int x = paths.keyAt(i);
             int y = paths.valueAt(i);
             if (y == PATH_DELIM) {
-                if (i == paths.size() - 1 && pendingYLoc != PATH_DELIM) {
-                    // Connect to the end of the graph.
-                    localPaths.put(pendingXLoc, pendingYLoc);
+                if (i == paths.size() - 1 && skippedLastPoint) {
+                    // Add back skipped point to complete the path.
+                    localPaths.put(lx, ly);
                 }
-                // Clear out any pending points.
-                pendingYLoc = PATH_DELIM;
-                localPaths.put(pendingXLoc + 1, PATH_DELIM);
+                skippedLastPoint = false;
+                localPaths.put(lx + 1, PATH_DELIM);
             } else {
-                final int lx = getX(x);
-                final int ly = getY(y);
-                pendingXLoc = lx;
+                lx = getX(x);
+                ly = getY(y);
+                // Skip this point if it is not far enough from the last one added.
                 if (localPaths.size() > 0) {
                     int lastX = localPaths.keyAt(localPaths.size() - 1);
                     int lastY = localPaths.valueAt(localPaths.size() - 1);
                     if (lastY != PATH_DELIM && !hasDiff(lastX, lx) && !hasDiff(lastY, ly)) {
-                        pendingYLoc = ly;
+                        skippedLastPoint = true;
                         continue;
                     }
                 }
+                skippedLastPoint = false;
                 localPaths.put(lx, ly);
             }
         }
-        BatteryUtils.logRuntime(LOG_TAG,"calculateLocalPaths", startTime);
+        BatteryUtils.logRuntime(LOG_TAG, "calculateLocalPaths", startTime);
     }
 
     private boolean hasDiff(int x1, int x2) {
@@ -221,8 +224,8 @@
 
     private void updateGradient() {
         mFillPaint.setShader(
-                new LinearGradient(0, 0, 0, getHeight(), getColor(mAccentColor, .2f), 0,
-                        TileMode.CLAMP));
+                new LinearGradient(
+                        0, 0, 0, getHeight(), getColor(mAccentColor, .2f), 0, TileMode.CLAMP));
     }
 
     private int getColor(int color, float alphaScale) {
@@ -236,7 +239,9 @@
         if (mMiddleDividerLoc != 0) {
             drawDivider(0, canvas, mTopDividerTint);
         }
-        drawDivider((int) ((canvas.getHeight() - mDividerSize) * mMiddleDividerLoc), canvas,
+        drawDivider(
+                (int) ((canvas.getHeight() - mDividerSize) * mMiddleDividerLoc),
+                canvas,
                 mMiddleDividerTint);
         drawDivider(canvas.getHeight() - mDividerSize, canvas, -1);
 
diff --git a/tests/robotests/src/com/android/settings/graph/UsageGraphTest.java b/tests/robotests/src/com/android/settings/graph/UsageGraphTest.java
new file mode 100644
index 0000000..fbd6fd4
--- /dev/null
+++ b/tests/robotests/src/com/android/settings/graph/UsageGraphTest.java
@@ -0,0 +1,154 @@
+/*
+ * Copyright (C) 2017 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.settings.graph;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.spy;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.util.SparseIntArray;
+
+import com.android.settings.TestConfig;
+import com.android.settingslib.R;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+import org.robolectric.annotation.Config;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION)
+public class UsageGraphTest {
+    private UsageGraph mGraph;
+
+    @Before
+    public void setUp() {
+        // Set up a graph view of width 1000, height 200, and corner radius 5.
+        Context context = spy(RuntimeEnvironment.application);
+        Resources resources = spy(context.getResources());
+        doReturn(resources).when(context).getResources();
+        doReturn(5).when(resources).getDimensionPixelSize(R.dimen.usage_graph_line_corner_radius);
+        doReturn(1).when(resources).getDimensionPixelSize(R.dimen.usage_graph_line_width);
+        doReturn(1).when(resources).getDimensionPixelSize(R.dimen.usage_graph_dot_size);
+        doReturn(1).when(resources).getDimensionPixelSize(R.dimen.usage_graph_dot_interval);
+        doReturn(1).when(resources).getDimensionPixelSize(R.dimen.usage_graph_divider_size);
+        mGraph = spy(new UsageGraph(context, null));
+        doReturn(1000).when(mGraph).getWidth();
+        doReturn(200).when(mGraph).getHeight();
+
+        // Set the conceptual size of the graph to 500ms x 100%.
+        mGraph.setMax(500, 100);
+    }
+
+    @Test
+    public void testCalculateLocalPaths_singlePath() {
+        SparseIntArray paths = new SparseIntArray();
+        paths.append(0, 100);
+        paths.append(500, 50);
+        paths.append(501, -1);
+
+        SparseIntArray localPaths = new SparseIntArray();
+        mGraph.calculateLocalPaths(paths, localPaths);
+
+        assertThat(localPaths.size()).isEqualTo(3);
+        assertThat(localPaths.keyAt(0)).isEqualTo(0);
+        assertThat(localPaths.valueAt(0)).isEqualTo(0);
+        assertThat(localPaths.keyAt(1)).isEqualTo(1000);
+        assertThat(localPaths.valueAt(1)).isEqualTo(100);
+        assertThat(localPaths.keyAt(2)).isEqualTo(1001);
+        assertThat(localPaths.valueAt(2)).isEqualTo(-1);
+    }
+
+    @Test
+    public void testCalculateLocalPaths_multiplePaths() {
+        SparseIntArray paths = new SparseIntArray();
+        paths.append(0, 100);
+        paths.append(200, 75);
+        paths.append(201, -1);
+
+        paths.append(300, 50);
+        paths.append(500, 25);
+        paths.append(501, -1);
+
+        SparseIntArray localPaths = new SparseIntArray();
+        mGraph.calculateLocalPaths(paths, localPaths);
+
+        assertThat(localPaths.size()).isEqualTo(6);
+
+        assertThat(localPaths.keyAt(0)).isEqualTo(0);
+        assertThat(localPaths.valueAt(0)).isEqualTo(0);
+        assertThat(localPaths.keyAt(1)).isEqualTo(400);
+        assertThat(localPaths.valueAt(1)).isEqualTo(50);
+        assertThat(localPaths.keyAt(2)).isEqualTo(401);
+        assertThat(localPaths.valueAt(2)).isEqualTo(-1);
+
+        assertThat(localPaths.keyAt(3)).isEqualTo(600);
+        assertThat(localPaths.valueAt(3)).isEqualTo(100);
+        assertThat(localPaths.keyAt(4)).isEqualTo(1000);
+        assertThat(localPaths.valueAt(4)).isEqualTo(150);
+        assertThat(localPaths.keyAt(5)).isEqualTo(1001);
+        assertThat(localPaths.valueAt(5)).isEqualTo(-1);
+    }
+
+    @Test
+    public void testCalculateLocalPaths_similarPointMiddle() {
+        SparseIntArray paths = new SparseIntArray();
+        paths.append(0, 100);
+        paths.append(1, 99); // This point should be omitted.
+        paths.append(500, 50);
+        paths.append(501, -1);
+
+        SparseIntArray localPaths = new SparseIntArray();
+        mGraph.calculateLocalPaths(paths, localPaths);
+
+        assertThat(localPaths.size()).isEqualTo(3);
+        assertThat(localPaths.keyAt(0)).isEqualTo(0);
+        assertThat(localPaths.valueAt(0)).isEqualTo(0);
+        assertThat(localPaths.keyAt(1)).isEqualTo(1000);
+        assertThat(localPaths.valueAt(1)).isEqualTo(100);
+        assertThat(localPaths.keyAt(2)).isEqualTo(1001);
+        assertThat(localPaths.valueAt(2)).isEqualTo(-1);
+    }
+
+    @Test
+    public void testCalculateLocalPaths_similarPointEnd() {
+        SparseIntArray paths = new SparseIntArray();
+        paths.append(0, 100);
+        paths.append(499, 51);
+        paths.append(500, 50); // This point should be kept: it's the last one.
+        paths.append(501, -1);
+
+        SparseIntArray localPaths = new SparseIntArray();
+        mGraph.calculateLocalPaths(paths, localPaths);
+
+        assertThat(localPaths.size()).isEqualTo(4);
+        assertThat(localPaths.keyAt(0)).isEqualTo(0);
+        assertThat(localPaths.valueAt(0)).isEqualTo(0);
+        assertThat(localPaths.keyAt(1)).isEqualTo(998);
+        assertThat(localPaths.valueAt(1)).isEqualTo(98);
+        assertThat(localPaths.keyAt(2)).isEqualTo(1000);
+        assertThat(localPaths.valueAt(2)).isEqualTo(100);
+        assertThat(localPaths.keyAt(3)).isEqualTo(1001);
+        assertThat(localPaths.valueAt(3)).isEqualTo(-1);
+    }
+}