BAEL-4631 (#11644)

* BAEL-4631

First code example draft

* BAEL-4631

Removed unnecesary constructors
Removed unnecessary comments
Removed unnecessary test

* BAEL-4631

Fixed xml files format

* BAEL-4631

Fixing pom.xml and testng.xml indentation

testing-modules/testng_command_line/src/main/java/com/baeldung/testing_modules/testng_command_line/DateSerializerService.java

@@ -0,0 +1,11 @@
+package com.baeldung.testing_modules.testng_command_line;
+
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+public class DateSerializerService {
+    public String serializeDate(Date date, String format) {
+        SimpleDateFormat dateFormat = new SimpleDateFormat(format);
+        return dateFormat.format(date);
+    }
+}

testing-modules/testng_command_line/src/test/java/com/baeldung/testing_modules/testng_command_line/DateSerializerServiceUnitTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.testing_modules.testng_command_line;
+
+import java.util.Date;
+
+import org.testng.annotations.BeforeClass;
+import org.testng.annotations.Test;
+
+@Test(testName = "Date Serializer")
+public class DateSerializerServiceUnitTest {
+    private DateSerializerService toTest;
+
+    @BeforeClass
+    public void beforeClass() {
+        toTest = new DateSerializerService();
+    }
+
+    @Test(expectedExceptions = { NullPointerException.class })
+    void givenNullDate_whenSerializeDate_thenThrowsException() {
+        Date dateToTest = null;
+
+        toTest.serializeDate(dateToTest, "yyyy/MM/dd HH:mm:ss.SSS");
+    }
+}