Completing OutlineRequiredOptionMissingException and corresponding tests

src/main/java/com/sangupta/outline/exceptions/OutlineRequiredOptionMissingException.java

@@ -21,6 +21,8 @@
 
 package com.sangupta.outline.exceptions;
 
+import com.sangupta.jerry.util.AssertUtils;
+
 public class OutlineRequiredOptionMissingException extends OutlineException {
 
 	/**
@@ -31,6 +33,10 @@ public class OutlineRequiredOptionMissingException extends OutlineException {
 	public final String argument;
 
 	public OutlineRequiredOptionMissingException(String argument) {
+		if(AssertUtils.isEmpty(argument)) {
+			throw new IllegalArgumentException("Argument that is invalid cannot be null/empty");
+		}
+
 		this.argument = argument;
 	}
 

src/test/java/com/sangupta/outline/exceptions/TestOutlineRequiredOptionMissingException.java

@@ -0,0 +1,31 @@
+package com.sangupta.outline.exceptions;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class TestOutlineRequiredOptionMissingException {
+
+	@Test
+	public void test() {
+		OutlineRequiredOptionMissingException ex = new OutlineRequiredOptionMissingException("hello");
+
+		Assert.assertNotNull(ex);
+		Assert.assertNotNull(ex.argument);
+		Assert.assertEquals("hello", ex.argument);
+
+		try {
+			ex = new OutlineRequiredOptionMissingException(null);
+			Assert.assertTrue(false);
+		} catch(IllegalArgumentException e) {
+			Assert.assertTrue(true);
+		}
+
+		try {
+			ex = new OutlineRequiredOptionMissingException("");
+			Assert.assertTrue(false);
+		} catch(IllegalArgumentException e) {
+			Assert.assertTrue(true);
+		}
+	}
+
+}