From 5b78803c1fe11f524c3a776a93a60a13052c7ee1 Mon Sep 17 00:00:00 2001
From: Grigorios Dimopoulos <grigoriosdimopoulos@gmail.com>
Date: Sat, 22 Sep 2018 17:37:09 +0300
Subject: [PATCH] [BAEL2150] Code for the related article, about nth root in
 java.

---
 .../root/calculator/NthRootCalculator.java    |  8 +++++
 .../java/com/baeldung/nth/root/main/Main.java | 13 +++++++
 .../calculator/NthRootCalculatorUnitTest.java | 21 ++++++++++++
 .../baeldung/nth/root/main/MainUnitTest.java  | 34 +++++++++++++++++++
 4 files changed, 76 insertions(+)
 create mode 100644 core-java/src/main/java/com/baeldung/nth/root/calculator/NthRootCalculator.java
 create mode 100644 core-java/src/main/java/com/baeldung/nth/root/main/Main.java
 create mode 100644 core-java/src/test/java/com/baeldung/nth/root/calculator/NthRootCalculatorUnitTest.java
 create mode 100644 core-java/src/test/java/com/baeldung/nth/root/main/MainUnitTest.java

diff --git a/core-java/src/main/java/com/baeldung/nth/root/calculator/NthRootCalculator.java b/core-java/src/main/java/com/baeldung/nth/root/calculator/NthRootCalculator.java
new file mode 100644
index 0000000000..217f1e06de
--- /dev/null
+++ b/core-java/src/main/java/com/baeldung/nth/root/calculator/NthRootCalculator.java
@@ -0,0 +1,8 @@
+package com.baeldung.nth.root.calculator;
+
+public class NthRootCalculator
+{
+    public Double calculate(Double base, Double n) {
+        return Math.pow(Math.E, Math.log(base)/n);
+    }
+}
diff --git a/core-java/src/main/java/com/baeldung/nth/root/main/Main.java b/core-java/src/main/java/com/baeldung/nth/root/main/Main.java
new file mode 100644
index 0000000000..3fcd36812f
--- /dev/null
+++ b/core-java/src/main/java/com/baeldung/nth/root/main/Main.java
@@ -0,0 +1,13 @@
+package com.baeldung.nth.root.main;
+
+import com.baeldung.nth.root.calculator.NthRootCalculator;
+
+public class Main {
+    public static void main(String[] args) {
+        NthRootCalculator calculator = new NthRootCalculator();
+        Double base = Double.parseDouble(args[0]);
+        Double n = Double.parseDouble(args[1]);
+        Double result = calculator.calculate(base, n);
+        System.out.println("The " + n + " root of " + base + " equals to " + result + ".");
+    }
+}
diff --git a/core-java/src/test/java/com/baeldung/nth/root/calculator/NthRootCalculatorUnitTest.java b/core-java/src/test/java/com/baeldung/nth/root/calculator/NthRootCalculatorUnitTest.java
new file mode 100644
index 0000000000..388bceef49
--- /dev/null
+++ b/core-java/src/test/java/com/baeldung/nth/root/calculator/NthRootCalculatorUnitTest.java
@@ -0,0 +1,21 @@
+package com.baeldung.nth.root.calculator;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.InjectMocks;
+import org.mockito.runners.MockitoJUnitRunner;
+
+import static org.junit.Assert.assertEquals;
+
+@RunWith(MockitoJUnitRunner.class)
+public class NthRootCalculatorUnitTest {
+
+    @InjectMocks
+    private NthRootCalculator nthRootCalculator;
+
+    @Test
+    public void giventThatTheBaseIs125_andTheExpIs3_whenCalculateIsCalled_thenTheResultIsTheCorrectOne() {
+       Double result = nthRootCalculator.calculate(125.0, 3.0);
+       assertEquals(result, (Double) 5.0d);
+    }
+}
diff --git a/core-java/src/test/java/com/baeldung/nth/root/main/MainUnitTest.java b/core-java/src/test/java/com/baeldung/nth/root/main/MainUnitTest.java
new file mode 100644
index 0000000000..a2fd839ba4
--- /dev/null
+++ b/core-java/src/test/java/com/baeldung/nth/root/main/MainUnitTest.java
@@ -0,0 +1,34 @@
+package com.baeldung.nth.root.main;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.InjectMocks;
+import static org.junit.Assert.assertEquals;
+
+public class MainUnitTest {
+    @InjectMocks
+    private Main main;
+
+    private final ByteArrayOutputStream outContent = new ByteArrayOutputStream();
+    private final PrintStream originalOut = System.out;
+
+    @Before
+    public void setUpStreams() {
+        System.setOut(new PrintStream(outContent));
+    }
+
+    @After
+    public void restoreStreams() {
+        System.setOut(originalOut);
+    }
+
+    @Test
+    public void givenThatTheBaseIs125_andTheExpIs3_whenMainIsCalled_thenTheCorrectResultIsPrinted() {
+        main.main(new String[]{"125.0", "3.0"});
+        assertEquals("The 3.0 root of 125.0 equals to 5.0.\n", outContent.toString().replaceAll("\r", ""));
+    }
+}