Added conjugationOf to the ComplexNumber object

src/main/java/com/ugsbo/complexnumcalc/ComplexNumber.java

@@ -137,4 +137,18 @@ public class ComplexNumber {
         return absoluteValue;
     }
 
+    /**
+     * Calucates the absolute value of this complex number
+     * @return the absolute value
+     */
+    public ComplexNumber conjugationOf(){
+        if(this.imaginaryPart.equals(Double.valueOf(0))){
+            return this;
+        } else {
+            this.imaginaryPart *= (-1);
+            return this;
+        }
+        
+    }
+
 }

src/test/java/com/ugsbo/complexnumcalc/conjugationOfComplexNumbersTest.java

@@ -0,0 +1,22 @@
+package com.ugsbo.complexnumcalc;
+
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+public class conjugationOfComplexNumbersTest {
+
+    @Test
+    public void TheConjugatedComplexNumberOfAComplexNumberWithOnlyARealPartShouldBeTheRealPart_ButItIsNot() { 
+        Double realPart = Double.valueOf(4);
+        Double imaginaryPart = Double.valueOf(0);
+        ComplexNumber complexNumber = new ComplexNumber(realPart, imaginaryPart);
+        ComplexNumber expected = new ComplexNumber(realPart, imaginaryPart);
+        
+        ComplexNumber actual = complexNumber.conjugationOf();
+
+        assertTrue("TheConjugatedComplexNumberOfAComplexNumberWithOnlyARealPartIsTheRealPart", expected.equals(actual));
+        //TODO change equals to equalTo
+        //assertThat("TheConjugatedComplexNumberOfAComplexNumberWithOnlyARealPartIsTheRealPart", expected, equalsTo(actual));
+    }
+}