Add unit tests for edu.princeton.cs.algs4.StdStats

pom.xml

@@ -82,5 +82,11 @@
 		</profile>
 	</profiles>
 	<dependencies>
-	</dependencies>  
+		<dependency>
+			<groupId>junit</groupId>
+			<artifactId>junit</artifactId>
+			<version>4.12</version>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
 </project>

src/test/java/edu/princeton/cs/algs4/StdStatsTest.java

@@ -0,0 +1,129 @@
+package edu.princeton.cs.algs4;
+
+import org.junit.Assert;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+public class StdStatsTest {
+
+    @Rule
+    public final ExpectedException thrown = ExpectedException.none();
+
+    @Test
+    public void testMaxDouble() {
+        Assert.assertEquals(Double.NaN,
+                StdStats.max(new double[]{Double.NaN}), 0.0);
+        Assert.assertEquals(8.5,
+                StdStats.max(new double[]{1.2, 3.3, 8.5, 2.3}), 0.0);
+        Assert.assertEquals(3.3,
+                StdStats.max(new double[]{1.2, 3.3, 8.5, 2.3}, 0, 2), 0.0);
+        Assert.assertEquals(Double.NaN,
+                StdStats.max(new double[]{Double.NaN, 3.3, 8.5, 2.3}, 0, 2),
+                0.0);
+    }
+
+    @Test
+    public void testMaxInt() {
+        Assert.assertEquals(8,
+                StdStats.max(new int[]{1, 3, 8, 2}), 0.0);
+    }
+
+    @Test
+    public void testMinDouble() {
+        Assert.assertEquals(Double.NaN,
+                StdStats.min(new double[]{Double.NaN}), 0.0);
+        Assert.assertEquals(1.2,
+                StdStats.min(new double[]{1.2, 3.3, 8.5, 2.3}), 0.0);
+        Assert.assertEquals(2.3,
+                StdStats.min(new double[]{1.2, 3.3, 8.5, 2.3}, 1, 4), 0.0);
+        Assert.assertEquals(Double.NaN,
+                StdStats.min(new double[]{Double.NaN, 3.3, 8.5, 2.3}, 0, 2),
+                0.0);
+    }
+
+    @Test
+    public void testMinInt() {
+        Assert.assertEquals(1, StdStats.min(new int[]{1, 3, 8, 2}), 0.0);
+    }
+
+    @Test
+    public void testMeanDouble() {
+        Assert.assertEquals(Double.NaN, StdStats.mean(new double[0]), 0.0);
+        Assert.assertEquals(3.825,
+                StdStats.mean(new double[]{1.2, 3.3, 8.5, 2.3}), 0.0);
+        Assert.assertEquals(4.7,
+                StdStats.mean(new double[]{1.2, 3.3, 8.5, 2.3}, 1, 4), 0.0);
+        Assert.assertEquals(Double.NaN,
+                StdStats.mean(new double[]{Double.NaN, 3.3}, 1, 1), 0.0);
+    }
+
+    @Test
+    public void testMeanInt() {
+        Assert.assertEquals(Double.NaN, StdStats.mean(new int[0]), 0.0);
+        Assert.assertEquals(3.5, StdStats.mean(new int[]{1, 3, 8, 2}), 0.0);
+    }
+
+    @Test
+    public void testVarDouble() {
+        Assert.assertEquals(Double.NaN, StdStats.var(new double[0]), 0.0);
+        Assert.assertEquals(10.449166666666668,
+                StdStats.var(new double[]{1.2, 3.3, 8.5, 2.3}), 0.0);
+        Assert.assertEquals(11.080000000000002,
+                StdStats.var(new double[]{1.2, 3.3, 8.5, 2.3}, 1, 4), 0.0);
+        Assert.assertEquals(Double.NaN,
+                StdStats.var(new double[]{Double.NaN, 3.3}, 1, 1), 0.0);
+    }
+
+    @Test
+    public void testVarInt() {
+        Assert.assertEquals(Double.NaN, StdStats.var(new int[0]), 0.0);
+        Assert.assertEquals(9.666666666666666,
+                StdStats.var(new int[]{1, 3, 8, 2}), 0.0);
+    }
+
+    @Test
+    public void testVarpDouble() {
+        Assert.assertEquals(Double.NaN, StdStats.varp(new double[0]), 0.0);
+        Assert.assertEquals(7.836875000000001,
+                StdStats.varp(new double[]{1.2, 3.3, 8.5, 2.3}), 0.0);
+        Assert.assertEquals(7.386666666666668,
+                StdStats.varp(new double[]{1.2, 3.3, 8.5, 2.3}, 1, 4), 0.0);
+        Assert.assertEquals(Double.NaN,
+                StdStats.varp(new double[]{Double.NaN, 3.3}, 1, 1), 0.0);
+    }
+
+    @Test
+    public void testStddevDouble() {
+        Assert.assertEquals(3.2325170790989906,
+                StdStats.stddev(new double[]{1.2, 3.3, 8.5, 2.3}), 0.0);
+        Assert.assertEquals(3.3286633954186478,
+                StdStats.stddev(new double[]{1.2, 3.3, 8.5, 2.3}, 1, 4), 0.0);
+    }
+
+    @Test
+    public void testStddevInt() {
+        Assert.assertEquals(3.1091263510296048,
+                StdStats.stddev(new int[]{1, 3, 8, 2}), 0.0);
+    }
+
+    @Test
+    public void testStddevpDouble() {
+        Assert.assertEquals(2.799441908666797,
+                StdStats.stddevp(new double[]{1.2, 3.3, 8.5, 2.3}), 0.0);
+        Assert.assertEquals(2.7178422814186014,
+                StdStats.stddevp(new double[]{1.2, 3.3, 8.5, 2.3}, 1, 4), 0.0);
+    }
+
+    @Test
+    public void testValidateNotNullThrowException() {
+        thrown.expect(IllegalArgumentException.class);
+        StdStats.stddev(null, 1, 4);
+    }
+
+    @Test
+    public void testValidateSubarrayIndicesThrowException() {
+        thrown.expect(IllegalArgumentException.class);
+        StdStats.stddev(new double[]{1.2, 3.3, 8.5, 2.3}, -1, 4);
+    }
+}