Add unit test for TelephonyHistogram class

Bug: 28717269
Change-Id: I3d30a4002bc3fb1074dae205f0b4a677368a7a02
diff --git a/tests/telephonytests/src/com/android/internal/telephony/TelephonyHistogramTest.java b/tests/telephonytests/src/com/android/internal/telephony/TelephonyHistogramTest.java
new file mode 100644
index 0000000..c65ce91
--- /dev/null
+++ b/tests/telephonytests/src/com/android/internal/telephony/TelephonyHistogramTest.java
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2016 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.internal.telephony;
+
+import android.telephony.TelephonyHistogram;
+import android.test.suitebuilder.annotation.SmallTest;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.Assert;
+
+import static org.junit.Assert.*;
+
+public class TelephonyHistogramTest {
+    private TelephonyHistogram mHistogram = null;
+
+    @After
+    public void tearDown() throws Exception {
+        mHistogram = null;
+    }
+
+    @Before
+    public void setUp() throws Exception {
+        mHistogram = new TelephonyHistogram(TelephonyHistogram.TELEPHONY_CATEGORY_RIL, 1, 3);
+    }
+
+    @Test
+    @SmallTest
+    public void testTelephonyHistogramConstructor() {
+        assertEquals(TelephonyHistogram.TELEPHONY_CATEGORY_RIL, mHistogram.getCategory());
+        assertEquals(1, mHistogram.getId());
+        assertEquals(Integer.MAX_VALUE, mHistogram.getMinTime());
+        assertEquals(0, mHistogram.getMaxTime());
+        assertEquals(0, mHistogram.getAverageTime());
+        assertEquals(0, mHistogram.getSampleCount());
+        assertEquals(3, mHistogram.getBucketCount());
+
+        // Test to verify that an exception is thrown when bucketCount <= 1
+        mHistogram = null;
+        try {
+            mHistogram = new TelephonyHistogram(TelephonyHistogram.TELEPHONY_CATEGORY_RIL, 1, 1);
+            Assert.fail("TelephonyHistogram should throw exception for bucketCount <= 1");
+        } catch (IllegalArgumentException ex) {
+            mHistogram = new TelephonyHistogram(TelephonyHistogram.TELEPHONY_CATEGORY_RIL, 1, 3);
+        }
+    }
+
+    @Test
+    @SmallTest
+    public void testAddTimeTaken() {
+        // Test when addTimeTaken is called less than 10 times
+        mHistogram.addTimeTaken(10);
+        mHistogram.addTimeTaken(20);
+        mHistogram.addTimeTaken(30);
+        mHistogram.addTimeTaken(40);
+        mHistogram.addTimeTaken(50);
+        assertEquals(10,mHistogram.getMinTime());
+        assertEquals(50, mHistogram.getMaxTime());
+        assertEquals(5, mHistogram.getSampleCount());
+        assertEquals(30, mHistogram.getAverageTime());
+        assertArrayEquals(new int[]{23, 36}, mHistogram.getBucketEndPoints());
+        assertArrayEquals(new int[]{2, 1, 2}, mHistogram.getBucketCounters());
+
+        // Test when addTimeTaken is called more than 10 times
+        mHistogram.addTimeTaken(60);
+        mHistogram.addTimeTaken(70);
+        mHistogram.addTimeTaken(80);
+        mHistogram.addTimeTaken(90);
+        mHistogram.addTimeTaken(100);
+        mHistogram.addTimeTaken(10);
+        mHistogram.addTimeTaken(100);
+        assertEquals(10,mHistogram.getMinTime());
+        assertEquals(100, mHistogram.getMaxTime());
+        assertEquals(12, mHistogram.getSampleCount());
+        assertEquals(54, mHistogram.getAverageTime());
+        assertArrayEquals(new int[]{40, 70}, mHistogram.getBucketEndPoints());
+        assertArrayEquals(new int[]{5, 3, 4}, mHistogram.getBucketCounters());
+    }
+}