Graceful message and exit for wrong value of phase

client/src/main/java/zingg/client/Client.java

@@ -131,6 +131,7 @@ public static void main(String... args) {
 				System.exit(0);
 			}
 			String phase = options.get(ClientOptions.PHASE).value.trim();
+			ZinggOptions.verifyPhase(phase);
 			Arguments arguments = null;
 			if (options.get(ClientOptions.CONF).value.endsWith("json")) {
 					arguments = Arguments.createArgumentsFromJSON(options.get(ClientOptions.CONF).value, phase);

client/src/main/java/zingg/client/ZinggOptions.java

@@ -2,6 +2,8 @@
 
 import java.util.Arrays;
 
+import zingg.client.util.Util;
+
 public enum ZinggOptions {
 
     TRAIN("train"), 
@@ -38,5 +40,11 @@ public static final ZinggOptions getByValue(String value){
         return null;
     }
 
-
+	public static void verifyPhase(String phase) throws ZinggClientException {
+		if (getByValue(phase) == null) {	
+			String message = "'" + phase + "' is not a valid phase. "
+			               + "Valid phases are: " + Util.join(getAllZinggOptions(), "|");
+			throw new ZinggClientException(message);
+		}
+	}
 }

client/src/test/java/zingg/client/TestClient.java

@@ -1,12 +1,29 @@
 package zingg.client;
 
+import static org.junit.Assert.fail;
+
 import org.junit.Test;
 
 public class TestClient {
-	
+
 	@Test
-	public void testInvalidArgs() {
-
+	public void testValidPhase() {
+		String phase = "train";
+		try {
+			ZinggOptions.verifyPhase(phase);
+		} catch (ZinggClientException e1) {
+			fail("No exception was expected as it is a valid phase: " + phase);
+		}
 	}
 
-}
+	@Test
+	public void testInvalidPhase() {
+		String phase = "tain";
+		try {
+			ZinggOptions.verifyPhase(phase);
+			fail("An exception should have been thrown for an invalid phase");
+		} catch (ZinggClientException e1) {
+			System.out.println("Expected exception as it is an invalid phase: " + phase);
+		}
+	}
+}