Added unit test for Source element

Author: magneticflux-

src/test/groovy/com/github/magneticflux/rss/namespaces/standard/elements/SourceTest.groovy

@@ -0,0 +1,25 @@
+package com.github.magneticflux.rss.namespaces.standard.elements
+
+import com.github.magneticflux.rss.PersisterSpecification
+import spock.lang.Unroll
+
+import static com.github.magneticflux.rss.UrlUtils.testUrl
+
+class SourceTest extends PersisterSpecification {
+	@Unroll
+	def 'enclosure #object read/write'() {
+
+		expect: 'the output XML equals the given XML'
+		persister.write(object) == xml
+
+		and: 'the input object equals the given object'
+		persister.read(Source, xml) == object
+
+		where:
+		url       | text       | xml
+		testUrl() | 'testText' | """<source url="$url">$text</source>"""
+		testUrl() | null       | """<source url="$url"/>"""
+
+		object = new Source(url, text)
+	}
+}