[grammar comparison] enhanced grammar comparator to ignore single & multi line comments, added corresponding tests, moved test helper methods & classes into new helper class

Signed-off-by: Christian Schneider <christian.schneider@itemis.de>

tests/org.eclipse.xtext.tests/src/org/eclipse/xtext/generator/parser/AntlrGrammarComparatorTest.xtend

@@ -7,11 +7,8 @@
  *******************************************************************************/
 package org.eclipse.xtext.generator.parser
 
-import org.eclipse.xtext.generator.parser.antlr.AntlrGrammarComparator
 import org.junit.Test
 
-import static org.junit.Assert.*
-
 /**
  * Contributes unit tests for {@link AntlrGrammarComparator}.
  * 
@@ -19,14 +16,8 @@ import static org.junit.Assert.*
  */
 class AntlrGrammarComparatorTest {
 
-	AntlrGrammarComparator comparator = new AntlrGrammarComparator
+	private extension AntlrGrammarComparatorTestHelper = new AntlrGrammarComparatorTestHelper();
 
-	TestErrorHandler errorHandler = new TestErrorHandler
-	
-	private def compare(CharSequence grammar, CharSequence grammarReference) {
-		comparator.compareGrammars(grammar, grammarReference, errorHandler);
-	}
-	
 	/**
 	 * The pattern of "\"" is not expected to occur in ANTLR grammar,
 	 *  so I use it for testing the unmatched token check.
@@ -324,28 +315,157 @@ class AntlrGrammarComparatorTest {
 		
 		testee.compare(expected)		
 	}
-
-
-
-	private static class TestErrorHandler implements AntlrGrammarComparator.IErrorHandler {
+	
+	@Test
+	def void sLCommentIgnoring01() {
+		val testee = '''
+			A: 'A'
+			
+			// rule B
+			B: 'B'
+		'''
 		
-		override handleMismatch(String match, String matchReference, AntlrGrammarComparator.ErrorContext context) {
-			fail('''
-				Inputs differs at token «match» (line «context.testedGrammar.lineNumber»), expected token «
-					matchReference» (line «context.referenceGrammar.lineNumber» ).
-			''')
-		}
+		val expected = '''
+			A: 'A'
+			
+			B: 'B'
+		'''
 		
-		override handleInvalidGeneratedGrammarFile(AntlrGrammarComparator.ErrorContext context) {
-			fail('''
-				Noticed an unmatched character sequence in 'testee' in/before line «context.testedGrammar.lineNumber».
-			''')
-		}
+		testee.compare(expected)
+	}
+	
+	@Test
+	def void sLCommentIgnoring01b() {
+		val testee = '''
+			A: 'A'
+			
+			B: 'B'
+		'''
 		
-		override handleInvalidReferenceGrammarFile(AntlrGrammarComparator.ErrorContext context) {
-			fail('''
-				Noticed an unmatched character sequence in 'expected' in/before line «context.referenceGrammar.lineNumber».
-			''')
-		}
+		val expected = '''
+			A: 'A'
+			
+			// rule B
+			B: 'B'
+		'''
+		
+		testee.compare(expected)
+	}
+	
+	@Test
+	def void mismatchWithSLComment01() {
+		val testee = '''
+			A: 'A'
+			
+			B: 'B'
+		'''
+		
+		val expected = '''
+			A: 'A'
+			
+			// rule B
+			B: 'C'
+		'''
+		
+		testee.compareAndExpectMismatchInLines(expected, 3, 4)
+	}
+	
+	@Test(expected = AssertionError)
+	def void mismatchWithSLComment01b() {
+		val testee = '''
+			A: 'A'
+			
+			B: 'B'
+		'''
+		
+		val expected = '''
+			A: 'A'
+			
+			// rule B
+			B: 'C'
+		'''
+		// expected to fail because of wrong 'lineNoTestee'
+		testee.compareAndExpectMismatchInLines(expected, 4, 4)
+	}
+	
+	@Test
+	def void mLCommentIgnoring01() {
+		val testee = '''
+			A: 'A'
+			
+			/*
+			 * rule B
+			 */
+			B: 'B'
+		'''
+		
+		val expected = '''
+			A: 'A'
+			
+			B: 'B'
+		'''
+		
+		testee.compare(expected)
+	}
+	
+	@Test
+	def void mLCommentIgnoring01b() {
+		val testee = '''
+			A: 'A'
+			
+			B: 'B'
+		'''
+		
+		val expected = '''
+			A: 'A'
+			
+			/*
+			 * rule B
+			 */
+			B: 'B'
+		'''
+		
+		testee.compare(expected)
+	}
+	
+	@Test
+	def void mismatchWithMLComment01() {
+		val testee = '''
+			A: 'A'
+			
+			B: 'B'
+		'''
+		
+		val expected = '''
+			A: 'A'
+			
+			/*
+			 * rule B
+			 */
+			B: 'C'
+		'''
+		
+		testee.compareAndExpectMismatchInLines(expected, 3, 6)
+	}
+	
+	@Test(expected = AssertionError)
+	def void mismatchWithMLComment01b() {
+		val testee = '''
+			A: 'A'
+			
+			B: 'B'
+		'''
+		
+		val expected = '''
+			A: 'A'
+			
+			/*
+			 * rule B
+			 */
+			B: 'C'
+		'''
+		
+		// expected to fail because of wrong 'lineNoExpected'
+		testee.compareAndExpectMismatchInLines(expected, 3, 5)
 	}
 }

tests/org.eclipse.xtext.tests/src/org/eclipse/xtext/generator/parser/AntlrGrammarComparatorTestHelper.xtend

@@ -0,0 +1,91 @@
+/*******************************************************************************
+ * Copyright (c) 2015 itemis AG (http://www.itemis.eu) and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *******************************************************************************/
+package org.eclipse.xtext.generator.parser
+
+import org.eclipse.xtext.generator.parser.antlr.AntlrGrammarComparator
+
+/**
+ * @author Christian Schneider - Initial contribution and API
+ */
+class AntlrGrammarComparatorTestHelper {
+
+	private val AntlrGrammarComparator comparator = new AntlrGrammarComparator
+	private val TestErrorHandler errorHandler = new TestErrorHandler
+
+	def compare(CharSequence grammar, CharSequence grammarReference) {
+		comparator.compareGrammars(grammar, grammarReference, errorHandler);
+	}
+
+	/**
+	 * This method delegates to 'compare(..., ...)' and expects a {@link ComparisonError} reporting a mismatch
+	 * in the given line numbers. If so the error is dropped. If the error reports different line numbers
+	 * the error is re-thrown indicating a failure in the test. If no error occurs in 'compare(..., ...)'
+	 * this test is supposed to fail. 
+	 */
+	def compareAndExpectMismatchInLines(String testee, String expected, int lineNoTestee, int lineNoExpected) {
+		try {			
+			testee.compare(expected)
+		} catch (ComparisonError e) {
+			if (lineNoTestee == e.lineNoTestee && lineNoExpected == e.lineNoExpected) {
+				return
+			} else {
+				throw e;				
+			}
+		}
+		
+		fail('''Expected mismatch in lines «lineNoTestee»/«lineNoExpected».''')
+	}
+
+	private def static fail(String msg) {
+		throw new ComparisonError(msg);
+	}
+
+	private def static fail(int lineNoTestee, int lineNoExpected, String msg) {
+		throw new ComparisonError(lineNoTestee, lineNoExpected, msg);
+	}
+
+	static class ComparisonError extends AssertionError {
+		
+		private val int lineNoTestee 
+		private val int lineNoExpected
+		
+		new(String msg) {
+			super(msg)
+			this.lineNoTestee = -1
+			this.lineNoExpected = -1
+		}
+		
+		new(int lineNoTestee, int lineNoExpected, String msg) {
+			super(msg)
+			this.lineNoTestee = lineNoTestee
+			this.lineNoExpected = lineNoExpected
+		}
+	}
+
+	private static class TestErrorHandler implements AntlrGrammarComparator.IErrorHandler {
+		
+		override handleMismatch(String match, String matchReference, AntlrGrammarComparator.ErrorContext context) {
+			fail(context.testedGrammar.lineNumber, context.referenceGrammar.lineNumber, '''
+				Inputs differs at token «match» (line «context.testedGrammar.lineNumber»), expected token «
+					matchReference» (line «context.referenceGrammar.lineNumber»).
+			''')
+		}
+		
+		override handleInvalidGeneratedGrammarFile(AntlrGrammarComparator.ErrorContext context) {
+			fail('''
+				Noticed an unmatched character sequence in 'testee' in/before line «context.testedGrammar.lineNumber».
+			''')
+		}
+		
+		override handleInvalidReferenceGrammarFile(AntlrGrammarComparator.ErrorContext context) {
+			fail('''
+				Noticed an unmatched character sequence in 'expected' in/before line «context.referenceGrammar.lineNumber».
+			''')
+		}
+	}
+}