Merge pull request #968 from akiellor/JENKINS-18434

core/src/main/java/hudson/model/ChoiceParameterDefinition.java

 package hudson.model;
 
+import hudson.util.FormValidation;
+import org.kohsuke.stapler.QueryParameter;
 import org.kohsuke.stapler.StaplerRequest;
 import org.kohsuke.stapler.DataBoundConstructor;
 import org.kohsuke.stapler.export.Exported;
@@ -15,25 +17,26 @@ import java.util.Arrays;
  * @author huybrechts
  */
 public class ChoiceParameterDefinition extends SimpleParameterDefinition {
+    public static final String CHOICES_DELIMETER = "\\r?\\n";
+
     private final List<String> choices;
     private final String defaultValue;
 
+    public static boolean areValidChoices(String choices) {
+        String strippedChoices = choices.trim();
+        return !StringUtils.isEmpty(strippedChoices) && strippedChoices.split(CHOICES_DELIMETER).length > 0;
+    }
+
     @DataBoundConstructor
     public ChoiceParameterDefinition(String name, String choices, String description) {
         super(name, description);
-        this.choices = Arrays.asList(choices.split("\\r?\\n"));
-        if (choices.length()==0) {
-            throw new IllegalArgumentException("No choices found");
-        }
+        this.choices = Arrays.asList(choices.split(CHOICES_DELIMETER));
         defaultValue = null;
     }
 
     public ChoiceParameterDefinition(String name, String[] choices, String description) {
         super(name, description);
         this.choices = new ArrayList<String>(Arrays.asList(choices));
-        if (this.choices.isEmpty()) {
-            throw new IllegalArgumentException("No choices found");
-        }
         defaultValue = null;
     }
 
@@ -52,7 +55,7 @@ public class ChoiceParameterDefinition extends SimpleParameterDefinition {
             return this;
         }
     }
-    
+
     @Exported
     public List<String> getChoices() {
         return choices;
@@ -95,6 +98,17 @@ public class ChoiceParameterDefinition extends SimpleParameterDefinition {
         public String getHelpFile() {
             return "/help/parameter/choice.html";
         }
+
+        /**
+         * Checks if parameterised build choices are valid.
+         */
+        public FormValidation doCheckChoices(@QueryParameter String value) {
+            if (ChoiceParameterDefinition.areValidChoices(value)) {
+                return FormValidation.ok();
+            } else {
+                return FormValidation.error(Messages.ChoiceParameterDefinition_MissingChoices());
+            }
+        }
     }
 
 }
\ No newline at end of file

core/src/main/resources/hudson/model/ChoiceParameterDefinition/config.jelly

@@ -30,7 +30,7 @@ THE SOFTWARE.
 		<f:textbox name="parameter.name" value="${instance.name}" />
 	</f:entry>
 	<f:entry title="${%Choices}" help="/help/parameter/choice-choices.html">
-		<f:textarea name="parameter.choices" value="${instance.choicesText}" />
+		<f:textarea checkUrl="'${rootURL}/descriptorByName/hudson.model.ChoiceParameterDefinition/checkChoices?value='+encodeURIComponent(this.value)" name="parameter.choices" value="${instance.choicesText}" />
 	</f:entry>
     <f:entry title="${%Description}" help="/help/parameter/description.html">
         <f:textarea name="parameter.description" value="${instance.description}" />

core/src/main/resources/hudson/model/Messages.properties

@@ -308,6 +308,7 @@ TextParameterDefinition.DisplayName=Text Parameter
 FileParameterDefinition.DisplayName=File Parameter
 BooleanParameterDefinition.DisplayName=Boolean Value
 ChoiceParameterDefinition.DisplayName=Choice
+ChoiceParameterDefinition.MissingChoices=Requires Choices.
 RunParameterDefinition.DisplayName=Run Parameter
 PasswordParameterDefinition.DisplayName=Password Parameter
 

core/src/test/java/hudson/model/ChoiceParameterDefinitionTest.java

+package hudson.model;
+
+import hudson.util.FormValidation;
+import jenkins.model.Jenkins;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class ChoiceParameterDefinitionTest {
+    @Test
+    public void shouldValidateChoices(){
+        assertFalse(ChoiceParameterDefinition.areValidChoices(""));
+        assertFalse(ChoiceParameterDefinition.areValidChoices("        "));
+        assertTrue(ChoiceParameterDefinition.areValidChoices("abc"));
+        assertTrue(ChoiceParameterDefinition.areValidChoices("abc\ndef"));
+        assertTrue(ChoiceParameterDefinition.areValidChoices("abc\r\ndef"));
+    }
+
+    @Test
+    public void testCheckChoices() throws Exception {
+        ChoiceParameterDefinition.DescriptorImpl descriptorImpl = new ChoiceParameterDefinition.DescriptorImpl();
+
+        assertEquals(FormValidation.Kind.OK, descriptorImpl.doCheckChoices("abc\ndef").kind);
+        assertEquals(FormValidation.Kind.ERROR, descriptorImpl.doCheckChoices("").kind);
+    }
+}