INT-3051 Derive Script Language from Extension

Make 'lang' attribute optional on a script element and
attempt to derive the language from the file extension.

Change return value on ScriptParser.deriveLanguageFromExtension to the language name

Polishing (PR Comments)

spring-integration-scripting/src/test/java/org/springframework/integration/scripting/jsr223/DeriveLanguageFromExtensionTests-context.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns="http://www.springframework.org/schema/beans"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xmlns:int-script="http://www.springframework.org/schema/integration/scripting"
+	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
+		http://www.springframework.org/schema/integration/scripting http://www.springframework.org/schema/integration/scripting/spring-integration-scripting.xsd">
+
+	<int-script:script location="foo.rb"/>
+	<int-script:script location="foo.groovy"/>
+	<int-script:script location="foo.js"/>
+	<int-script:script location="foo.py"/>
+</beans>

spring-integration-scripting/src/test/java/org/springframework/integration/scripting/jsr223/DeriveLanguageFromExtensionTests-fail1-context.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns="http://www.springframework.org/schema/beans"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xmlns:int-script="http://www.springframework.org/schema/integration/scripting"
+	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
+		http://www.springframework.org/schema/integration/scripting http://www.springframework.org/schema/integration/scripting/spring-integration-scripting.xsd">
+
+	<int-script:script location="foo.xx"/>
+</beans>

spring-integration-scripting/src/test/java/org/springframework/integration/scripting/jsr223/DeriveLanguageFromExtensionTests-fail2-context.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns="http://www.springframework.org/schema/beans"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xmlns:int-script="http://www.springframework.org/schema/integration/scripting"
+	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
+		http://www.springframework.org/schema/integration/scripting http://www.springframework.org/schema/integration/scripting/spring-integration-scripting.xsd">
+
+	<int-script:script location="foo"/>
+</beans>

spring-integration-scripting/src/test/java/org/springframework/integration/scripting/jsr223/DeriveLanguageFromExtensionTests.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2002-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+package org.springframework.integration.scripting.jsr223;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.util.Map;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.support.ClassPathXmlApplicationContext;
+import org.springframework.integration.test.util.TestUtils;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+/**
+ * @author David Turanski
+ *
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration
+public class DeriveLanguageFromExtensionTests {
+	@Autowired
+	private ApplicationContext ctx;
+
+	@Test
+	public void testParseLanguage() {
+		String langs[] = { "ruby", "Groovy", "ECMAScript", "python" };
+		Class<?> executors[] = {
+				RubyScriptExecutor.class,
+				DefaultScriptExecutor.class,
+				DefaultScriptExecutor.class,
+				PythonScriptExecutor.class
+		};
+
+		Map<String, ScriptExecutingMessageProcessor> scriptProcessors = ctx
+				.getBeansOfType(ScriptExecutingMessageProcessor.class);
+		assertEquals(4, scriptProcessors.size());
+
+		for (int i = 0; i < 4; i++) {
+
+			ScriptExecutingMessageProcessor processor = ctx.getBean(
+					"org.springframework.integration.scripting.jsr223.ScriptExecutingMessageProcessor#" + i,
+					ScriptExecutingMessageProcessor.class);
+
+			AbstractScriptExecutor executor = (AbstractScriptExecutor) TestUtils.getPropertyValue(processor,
+					"scriptExecutor");
+			assertEquals(langs[i], executor.language);
+			assertEquals(executors[i], executor.getClass());
+		}
+	}
+
+	@Test
+	public void testBadExtension() {
+		try {
+			new ClassPathXmlApplicationContext(this.getClass().getSimpleName() + "-fail1-context.xml", this.getClass());
+		}
+		catch (Exception e) {
+			assertTrue(e.getMessage().contains("No suitable scripting engine found for extension 'xx'"));
+		}
+	}
+
+	@Test
+	public void testNoExtension() {
+		try {
+			new ClassPathXmlApplicationContext(this.getClass().getSimpleName() + "-fail2-context.xml", this.getClass());
+		}
+		catch (Exception e) {
+			assertTrue(e.getMessage().contains("Unable to determine language for script 'foo'"));
+		}
+	}
+
+}