@Test
	public void duplicateExplicitLabels() {
		checkForParseError("xxx: http | xxx: file", XDDSLMessages.DUPLICATE_LABEL, 12, "xxx", "http", 0, "file", 1);
		checkForParseError("xxx: http | yyy: filter | transform | xxx: transform | file",
				XDDSLMessages.DUPLICATE_LABEL, 38, "xxx", "http", 0, "transform", 3);
		checkForParseError("xxx: http | yyy: filter | transform | xxx: transform | xxx: file",
				XDDSLMessages.DUPLICATE_LABEL, 38, "xxx", "http", 0, "transform", 3);
	}
Parse streams and verify either the correct abstract syntax tree is produced or the current exception comes out.

@author Andy Clement
@author David Turanski
spring-xd-dirt/src/test/java/org/springframework/xd/dirt/stream/dsl/StreamConfigParserTests.java