New Features in JUnit 4.x

Transcript

1. New Features in JUnit 4.x Marc Philipp March 14, 2011
2. About JUnit Kent Beck: A programmer-oriented testing framework for Java. David Saff: JUnit is the intersection of all possible useful Java test frameworks, not their union. Not only for Unit Tests! March 14, 2011 2
3. A presentation about JUnit? Every Java developer knows JUnit. Really? Everyone thinks he knows JUnit. I thought so, too. However, a lot has happended since release 4.0! March 14, 2011 3
4. A presentation about JUnit? Every Java developer knows JUnit. Really? Everyone thinks he knows JUnit. I thought so, too. However, a lot has happended since release 4.0! March 14, 2011 3
5. A presentation about JUnit? Every Java developer knows JUnit. Really? Everyone thinks he knows JUnit. I thought so, too. However, a lot has happended since release 4.0! March 14, 2011 3
6. A presentation about JUnit? Every Java developer knows JUnit. Really? Everyone thinks he knows JUnit. I thought so, too. However, a lot has happended since release 4.0! March 14, 2011 3
7. A presentation about JUnit? Every Java developer knows JUnit. Really? Everyone thinks he knows JUnit. I thought so, too. However, a lot has happended since release 4.0! March 14, 2011 3
8. New Features since 4.0 JUnit 4.8.2 Matchers Theories Rules Categories March 14, 2011 4
9. Matchers René Magritte, Untitled 5
10. New Assertion: assertThat(...) New Assert methods: <T> void assertThat(T actual, Matcher<T> matcher) <T> void assertThat(String reason, T actual, Matcher<T> matcher) Parameters: reason description displayed when assertion fails (optional) actual actual value matcher Hamcrest matcher that checks the actual value March 14, 2011 6
11. Increased Readability import static org.hamcrest.CoreMatchers.is; public class BetterReadability { @Test public void withoutMatchers() { assertEquals(2, 1 + 1); } @Test public void withMatchers() { assertThat(1 + 1, is(2)); } } No more guessing about order of arguments Often more readable than traditional assertions March 14, 2011 7
12. Increased Readability import static org.hamcrest.CoreMatchers.is; public class BetterReadability { @Test public void withoutMatchers() { assertEquals(2, 1 + 1); } @Test public void withMatchers() { assertThat(1 + 1, is(2)); } } No more guessing about order of arguments Often more readable than traditional assertions March 14, 2011 7
13. Increased Readability import static org.hamcrest.CoreMatchers.is; public class BetterReadability { @Test public void withoutMatchers() { assertEquals(2, 1 + 1); } @Test public void withMatchers() { assertThat(1 + 1, is(2)); } } No more guessing about order of arguments Often more readable than traditional assertions March 14, 2011 7
14. Increased Readability import static org.hamcrest.CoreMatchers.is; public class BetterReadability { @Test public void withoutMatchers() { assertEquals(2, 1 + 1); } @Test public void withMatchers() { assertThat(1 + 1, is(2)); } } No more guessing about order of arguments Often more readable than traditional assertions March 14, 2011 7
15. Combining Matchers Matchers are easily combined: assertThat(1 + 1, is(not(3))); assertThat(1 + 1, both(greaterThan(1)).and(lessThan(3))); March 14, 2011 8
16. Expressive Failure Messages Traditional assertions without description assertFalse(asList(1, 2, 3).contains(2)); Result: AssertionError: at de.andrena.junit... New assertion with matcher assertThat(asList(1, 2, 3), not(hasItem(2))); Result: AssertionError: Expected: not a collection containing <2> got: <[1, 2, 3]> March 14, 2011 9
17. Expressive Failure Messages Traditional assertions without description assertFalse(asList(1, 2, 3).contains(2)); Result: AssertionError: at de.andrena.junit... New assertion with matcher assertThat(asList(1, 2, 3), not(hasItem(2))); Result: AssertionError: Expected: not a collection containing <2> got: <[1, 2, 3]> March 14, 2011 9
18. Predefined Matchers Numerous predefined matchers: Core is, not, allOf, anyOf, nullValue, . . . Strings containsString, startsWith, endsWith, . . . Collections hasItem, hasItems, isIn, empty, hasSize, . . . JUnit includes only a small fraction: org.hamcrest.CoreMatchers org.junit.matchers.JUnitMatchers Hamcrest offers additional matchers (hamcrest-all.jar). In addition, you can write your own matchers. March 14, 2011 10
19. Predefined Matchers Numerous predefined matchers: Core is, not, allOf, anyOf, nullValue, . . . Strings containsString, startsWith, endsWith, . . . Collections hasItem, hasItems, isIn, empty, hasSize, . . . JUnit includes only a small fraction: org.hamcrest.CoreMatchers org.junit.matchers.JUnitMatchers Hamcrest offers additional matchers (hamcrest-all.jar). In addition, you can write your own matchers. March 14, 2011 10
20. A Custom Matcher Implementation public class IsEmptyCollection extends TypeSafeMatcher<Collection<?>> { @Override protected boolean matchesSafely(Collection<?> collection) { return collection.isEmpty(); } @Override public void describeTo(Description description) { description.appendText("empty"); } @Factory public static Matcher<Collection<?>> empty() { return new IsEmptyCollection(); } } March 14, 2011 11
21. A Custom Matcher Implementation public class IsEmptyCollection extends TypeSafeMatcher<Collection<?>> { @Override protected boolean matchesSafely(Collection<?> collection) { return collection.isEmpty(); } @Override public void describeTo(Description description) { description.appendText("empty"); } @Factory public static Matcher<Collection<?>> empty() { return new IsEmptyCollection(); } } March 14, 2011 11
22. A Custom Matcher Implementation public class IsEmptyCollection extends TypeSafeMatcher<Collection<?>> { @Override protected boolean matchesSafely(Collection<?> collection) { return collection.isEmpty(); } @Override public void describeTo(Description description) { description.appendText("empty"); } @Factory public static Matcher<Collection<?>> empty() { return new IsEmptyCollection(); } } March 14, 2011 11
23. A Custom Matcher Usage public class CollectionMatchersTest { @Test public void isEmpty() { TreeSet<String> set = new TreeSet<String>(); assertThat(set, new IsEmptyCollection()); // direct instantiation assertThat(set, IsEmptyCollection.empty()); // using @Factory method assertThat(set, empty()); // using static import assertThat(set, is(empty())); // syntactic sugar } } March 14, 2011 12
24. Many Matchers – Many Classes Problem Lots of matcher classes with static methods we would like to import Requires manual setup of preferences in IDE . . . for all developers! Solution Generate your own matcher library March 14, 2011 13
25. Generating a Custom Matcher Library 1. Configuration in XML <matchers> <factory class="org.hamcrest.core.Is"/> <factory class="de.andrena.junit.hamcrest.IsEmptyCollection"/> </matchers> 2. Run org.hamcrest.generator.config.XmlConfigurator 3. Combines all @Factory methods into a single generated class: public class Matchers { public static <T> Matcher<? super T> is(T param1) { return org.hamcrest.core.Is.is(param1); } /* ... */ public static Matcher<Collection<?>> empty() { return de.andrena.junit.hamcrest.IsEmptyCollection.empty(); } } March 14, 2011 14
26. Summary: Matchers Assertions can often be expressed more elegantly Old assertion methods are still clearer sometimes Problem Java type system often gets in one’s way Requires boxing for primitive types assertThat(1 + 1, is(2)) Insufficient type inference assertThat(new TreeSet<String>(), Matchers.<String>empty()); March 14, 2011 15
27. Theories Wassily Kandinsky, Composition VIII 16
28. Parameterized Tests Parameterized test runner included since JUnit 4.0 Allows to supply parameters to test class constructors Arguments are defined in a public, static method @Parameters annotation Return type: List<Object[]> The runner creates an instance of the test class for each pair of test method and argument definition and executes the test. Useful when testing a calculation with a large number of input values. March 14, 2011 17
29. Parameterized Tests Example: Fibonacci Numbers @RunWith(Parameterized.class) public class FibonacciParameterizedTest { @Parameters public static List<Object[]> data() { return Arrays.asList(new Object[][] { { 0, 0 }, { 1, 1 }, { 2, 1 }, { 3, 2 }, { 4, 3 }, { 5, 5 }, { 6, 8 } }); } private final int input, expected; public FibonacciParameterizedTest(int input, int expected) { this.input = input; this.expected = expected; } @Test public void test() { assertEquals(expected, Fibonacci.compute(input)); } } March 14, 2011 18
30. Parameterized Tests Example: Fibonacci Numbers @RunWith(Parameterized.class) public class FibonacciParameterizedTest { @Parameters public static List<Object[]> data() { return Arrays.asList(new Object[][] { { 0, 0 }, { 1, 1 }, { 2, 1 }, { 3, 2 }, { 4, 3 }, { 5, 5 }, { 6, 8 } }); } private final int input, expected; public FibonacciParameterizedTest(int input, int expected) { this.input = input; this.expected = expected; } @Test public void test() { assertEquals(expected, Fibonacci.compute(input)); } } March 14, 2011 18
31. Parameterized Tests Example: Fibonacci Numbers @RunWith(Parameterized.class) public class FibonacciParameterizedTest { @Parameters public static List<Object[]> data() { return Arrays.asList(new Object[][] { { 0, 0 }, { 1, 1 }, { 2, 1 }, { 3, 2 }, { 4, 3 }, { 5, 5 }, { 6, 8 } }); } private final int input, expected; public FibonacciParameterizedTest(int input, int expected) { this.input = input; this.expected = expected; } @Test public void test() { assertEquals(expected, Fibonacci.compute(input)); } } March 14, 2011 18
32. Theories Introduced in release 4.4 Parameterized test method with preconditions (assumptions) assumeThat() assumeTrue() assumeNotNull() @Theory instead of @Test Input for test methods via @DataPoint(s) annotation March 14, 2011 19
33. Theories Example: Fibonacci Numbers import static de.andrena.junit.fibonacci.Fibonacci.compute; @RunWith(Theories.class) public class FibonacciTheories { @DataPoints public static int[] VALUES = { 0, 1, 2, 3, 4, 5, 6 }; @Theory public void seeds(int n) { // F(0) = 0, F(1) = 1 assumeTrue(n <= 1); assertEquals(n, compute(n)); } @Theory public void recurrence(int n) { // F(n) = F(n − 1) + F(n − 2) for n > 1 assumeTrue(n > 1); assertEquals(compute(n - 1) + compute(n - 2), compute(n)); } } March 14, 2011 20
34. Theories Example: Fibonacci Numbers import static de.andrena.junit.fibonacci.Fibonacci.compute; @RunWith(Theories.class) public class FibonacciTheories { @DataPoints public static int[] VALUES = { 0, 1, 2, 3, 4, 5, 6 }; @Theory public void seeds(int n) { // F(0) = 0, F(1) = 1 assumeTrue(n <= 1); assertEquals(n, compute(n)); } @Theory public void recurrence(int n) { // F(n) = F(n − 1) + F(n − 2) for n > 1 assumeTrue(n > 1); assertEquals(compute(n - 1) + compute(n - 2), compute(n)); } } March 14, 2011 20
35. Theories Example: Fibonacci Numbers import static de.andrena.junit.fibonacci.Fibonacci.compute; @RunWith(Theories.class) public class FibonacciTheories { @DataPoints public static int[] VALUES = { 0, 1, 2, 3, 4, 5, 6 }; @Theory public void seeds(int n) { // F(0) = 0, F(1) = 1 assumeTrue(n <= 1); assertEquals(n, compute(n)); } @Theory public void recurrence(int n) { // F(n) = F(n − 1) + F(n − 2) for n > 1 assumeTrue(n > 1); assertEquals(compute(n - 1) + compute(n - 2), compute(n)); } } March 14, 2011 20
36. Theories Example: Fibonacci Numbers import static de.andrena.junit.fibonacci.Fibonacci.compute; @RunWith(Theories.class) public class FibonacciTheories { @DataPoints public static int[] VALUES = { 0, 1, 2, 3, 4, 5, 6 }; @Theory public void seeds(int n) { // F(0) = 0, F(1) = 1 assumeTrue(n <= 1); assertEquals(n, compute(n)); } @Theory public void recurrence(int n) { // F(n) = F(n − 1) + F(n − 2) for n > 1 assumeTrue(n > 1); assertEquals(compute(n - 1) + compute(n - 2), compute(n)); } } March 14, 2011 20
37. Theories Example: Fibonacci Numbers import static de.andrena.junit.fibonacci.Fibonacci.compute; @RunWith(Theories.class) public class FibonacciTheories { @DataPoints public static int[] VALUES = { 0, 1, 2, 3, 4, 5, 6 }; @Theory public void seeds(int n) { // F(0) = 0, F(1) = 1 assumeTrue(n <= 1); assertEquals(n, compute(n)); } @Theory public void recurrence(int n) { // F(n) = F(n − 1) + F(n − 2) for n > 1 assumeTrue(n > 1); assertEquals(compute(n - 1) + compute(n - 2), compute(n)); } } March 14, 2011 20
38. Theories Example: Fibonacci Numbers import static de.andrena.junit.fibonacci.Fibonacci.compute; @RunWith(Theories.class) public class FibonacciTheories { @DataPoints public static int[] VALUES = { 0, 1, 2, 3, 4, 5, 6 }; @Theory public void seeds(int n) { // F(0) = 0, F(1) = 1 assumeTrue(n <= 1); assertEquals(n, compute(n)); } @Theory public void recurrence(int n) { // F(n) = F(n − 1) + F(n − 2) for n > 1 assumeTrue(n > 1); assertEquals(compute(n - 1) + compute(n - 2), compute(n)); } } March 14, 2011 20
39. Theories Example: Fibonacci Numbers import static de.andrena.junit.fibonacci.Fibonacci.compute; @RunWith(Theories.class) public class FibonacciTheories { @DataPoints public static int[] VALUES = { 0, 1, 2, 3, 4, 5, 6 }; @Theory public void seeds(int n) { // F(0) = 0, F(1) = 1 assumeTrue(n <= 1); assertEquals(n, compute(n)); } @Theory public void recurrence(int n) { // F(n) = F(n − 1) + F(n − 2) for n > 1 assumeTrue(n > 1); assertEquals(compute(n - 1) + compute(n - 2), compute(n)); } } March 14, 2011 20
40. Theories Example: @DataPoints of different types @RunWith(Theories.class) public class DifferentDataPoints { @DataPoint public static String A = "a"; @DataPoint public static String B = "b"; @DataPoints public static int[] NUMBERS = { 1, 2, 3 }; @Theory public void theory1(String string) { /* ("a"), ("b") */ } @Theory public void theory2(int number) { /* (1), (2), (3) */ } @Theory public void theory3(String string, int number) { /* ("a", 1), ("a", 2), ("a", 3), ("b", 1), ("b", 2), ("b", 3) */ } } March 14, 2011 21
41. Theories Example: @DataPoints of different types @RunWith(Theories.class) public class DifferentDataPoints { @DataPoint public static String A = "a"; @DataPoint public static String B = "b"; @DataPoints public static int[] NUMBERS = { 1, 2, 3 }; @Theory public void theory1(String string) { /* ("a"), ("b") */ } @Theory public void theory2(int number) { /* (1), (2), (3) */ } @Theory public void theory3(String string, int number) { /* ("a", 1), ("a", 2), ("a", 3), ("b", 1), ("b", 2), ("b", 3) */ } } March 14, 2011 21
42. Theories Example: @DataPoints of different types @RunWith(Theories.class) public class DifferentDataPoints { @DataPoint public static String A = "a"; @DataPoint public static String B = "b"; @DataPoints public static int[] NUMBERS = { 1, 2, 3 }; @Theory public void theory1(String string) { /* ("a"), ("b") */ } @Theory public void theory2(int number) { /* (1), (2), (3) */ } @Theory public void theory3(String string, int number) { /* ("a", 1), ("a", 2), ("a", 3), ("b", 1), ("b", 2), ("b", 3) */ } } March 14, 2011 21
43. Theories Example: @DataPoints of different types @RunWith(Theories.class) public class DifferentDataPoints { @DataPoint public static String A = "a"; @DataPoint public static String B = "b"; @DataPoints public static int[] NUMBERS = { 1, 2, 3 }; @Theory public void theory1(String string) { /* ("a"), ("b") */ } @Theory public void theory2(int number) { /* (1), (2), (3) */ } @Theory public void theory3(String string, int number) { /* ("a", 1), ("a", 2), ("a", 3), ("b", 1), ("b", 2), ("b", 3) */ } } March 14, 2011 21
44. Theories Example: @DataPoints of different types @RunWith(Theories.class) public class DifferentDataPoints { @DataPoint public static String A = "a"; @DataPoint public static String B = "b"; @DataPoints public static int[] NUMBERS = { 1, 2, 3 }; @Theory public void theory1(String string) { /* ("a"), ("b") */ } @Theory public void theory2(int number) { /* (1), (2), (3) */ } @Theory public void theory3(String string, int number) { /* ("a", 1), ("a", 2), ("a", 3), ("b", 1), ("b", 2), ("b", 3) */ } } March 14, 2011 21
45. Parameterized Tests vs. Theories @DataPoint definition is more flexible Constants or methods Any number of datapoints Different types Test methods are parameterized No boilerplate code (Constructor + instance variables) Different types of parameters possible Theories can do everything Parameterized tests can, but more! March 14, 2011 22
46. Traditional Tests vs. Theories Traditional tests use examples: Validation of behaviour under selected inputs Examples ought to be characteristic (hopefully) A theory generalizes a set of tests: precondition is made explicit assertions apply for all inputs that satisfy preconditions March 14, 2011 23
47. Rules René Magritte, Golconda 24
48. What is a Rule? Extension mechanism for execution of test methods Examples: Execute code before/after every test method Handle failed tests Check additonal criteria after every test . . . March 14, 2011 25
49. What is a Rule? Extension mechanism for execution of test methods Examples: Execute code before/after every test method Handle failed tests Check additonal criteria after every test . . . March 14, 2011 25
50. Example: TemporaryFolder Without Rules public class TemporaryFolderWithoutRule { private File folder; @Before public void createTemporaryFolder() throws Exception { folder = File.createTempFile("myFolder", ""); folder.delete(); folder.mkdir(); } @Test public void test() throws Exception { File file = new File(folder, "test.txt"); file.createNewFile(); assertTrue(file.exists()); } @After public void deleteTemporaryFolder() { recursivelyDelete(folder); // does not fit on current slide... } March 14, 2011 26
51. Example: TemporaryFolder Without Rules public class TemporaryFolderWithoutRule { private File folder; @Before public void createTemporaryFolder() throws Exception { folder = File.createTempFile("myFolder", ""); folder.delete(); folder.mkdir(); } @Test public void test() throws Exception { File file = new File(folder, "test.txt"); file.createNewFile(); assertTrue(file.exists()); } @After public void deleteTemporaryFolder() { recursivelyDelete(folder); // does not fit on current slide... } March 14, 2011 26
52. Example: TemporaryFolder With Rules public class TemporaryFolderWithRule { @Rule public TemporaryFolder folder = new TemporaryFolder(); @Test public void test() throws Exception { File file = folder.newFile("test.txt"); assertTrue(file.exists()); } } March 14, 2011 27
53. Example: TemporaryFolder With Rules public class TemporaryFolderWithRule { @Rule public TemporaryFolder folder = new TemporaryFolder(); @Test public void test() throws Exception { File file = folder.newFile("test.txt"); assertTrue(file.exists()); } } March 14, 2011 27
54. What is a Rule? Extension mechanism for execution of test methods Examples: Execute code before/after every test method Handle failed tests Check additonal criteria after every test . . . March 14, 2011 28
55. Example: ExpectedException Without Rules public class ExpectedExceptionWithoutRule { int[] threeNumbers = { 1, 2, 3 }; @Test(expected = ArrayIndexOutOfBoundsException.class) public void exception() { threeNumbers[3] = 4; } @Test public void exceptionWithMessage() { try { threeNumbers[3] = 4; fail("ArrayIndexOutOfBoundsException expected"); } catch (ArrayIndexOutOfBoundsException expected) { assertEquals("3", expected.getMessage()); } } } March 14, 2011 29
56. Example: ExpectedException Without Rules public class ExpectedExceptionWithoutRule { int[] threeNumbers = { 1, 2, 3 }; @Test(expected = ArrayIndexOutOfBoundsException.class) public void exception() { threeNumbers[3] = 4; } @Test public void exceptionWithMessage() { try { threeNumbers[3] = 4; fail("ArrayIndexOutOfBoundsException expected"); } catch (ArrayIndexOutOfBoundsException expected) { assertEquals("3", expected.getMessage()); } } } March 14, 2011 29
57. Example: ExpectedException With Rules public class ExpectedExceptionWithRule { int[] threeNumbers = { 1, 2, 3 }; @Rule public ExpectedException thrown = ExpectedException.none(); @Test public void exception() { thrown.expect(ArrayIndexOutOfBoundsException.class); threeNumbers[3] = 4; } @Test public void exceptionWithMessage() { thrown.expect(ArrayIndexOutOfBoundsException.class); thrown.expectMessage("3"); threeNumbers[3] = 4; } } March 14, 2011 30
58. Example: ExpectedException With Rules public class ExpectedExceptionWithRule { int[] threeNumbers = { 1, 2, 3 }; @Rule public ExpectedException thrown = ExpectedException.none(); @Test public void exception() { thrown.expect(ArrayIndexOutOfBoundsException.class); threeNumbers[3] = 4; } @Test public void exceptionWithMessage() { thrown.expect(ArrayIndexOutOfBoundsException.class); thrown.expectMessage("3"); threeNumbers[3] = 4; } } March 14, 2011 30
59. Other Predefined Rules ErrorCollector Collects failing assertions and causes the test to fail with an aggregated list of failures at the end. TestName Provides access to the name of the currently executing test method. Timeout Applies the same timeout to all test methods in the test class. March 14, 2011 31
60. Write Your Own Rules! March 14, 2011 32
61. Write Your Own Rules! March 14, 2011 32
62. Custom Rule Implementation public class SystemProperty extends ExternalResource { private final String key, value; private String oldValue; public SystemProperty(String key, String value) { this.key = key; this.value = value; } @Override protected void before() { oldValue = System.getProperty(key); System.setProperty(key, value); } @Override protected void after() { if (oldValue == null) { System.getProperties().remove(key); } else { System.setProperty(key, oldValue); } } } March 14, 2011 33
63. Custom Rule Implementation public class SystemProperty extends ExternalResource { private final String key, value; private String oldValue; public SystemProperty(String key, String value) { this.key = key; this.value = value; } @Override protected void before() { oldValue = System.getProperty(key); System.setProperty(key, value); } @Override protected void after() { if (oldValue == null) { System.getProperties().remove(key); } else { System.setProperty(key, oldValue); } } } March 14, 2011 33
64. Custom Rule Usage public class SomeTestUsingSystemProperty { private static final String VALUE = "someValue"; private static final String KEY = "someKey"; @Rule public SystemProperty systemProperty = new SystemProperty(KEY, VALUE); @Test public void test() { assertThat(System.getProperty(KEY), is(VALUE)); } } March 14, 2011 34
65. Custom Rule Usage public class SomeTestUsingSystemProperty { private static final String VALUE = "someValue"; private static final String KEY = "someKey"; @Rule public SystemProperty systemProperty = new SystemProperty(KEY, VALUE); @Test public void test() { assertThat(System.getProperty(KEY), is(VALUE)); } } March 14, 2011 34
66. Advantages of Rules Reusable Allow to encapsulate frequently used code. Composable You can use any number of rules in one test class. Delegation over inheritance Help to avoid test class hierarchies. Extendable Writing your own rules is easy. March 14, 2011 35
67. Categories Piet Mondrian, Composition with Gray and Light Brown 36
68. Dividing Tests into Categories Category is class or interface: public interface Slow {} Only for one test: @Category(Slow.class) @Test public void test() {} All tests in a test class: @Category(Slow.class) public class B { @Test public void c() {} } March 14, 2011 37
69. Executing All Tests in Certain Categories Conventional test suite: @RunWith(Suite.class) @SuiteClasses( { A.class, B.class }) public class AllTests {} All tests in category Slow: @RunWith(Categories.class) @IncludeCategory(Slow.class) public class AllSlowTests extends AllTests {} All other tests: @RunWith(Categories.class) @ExcludeCategory(Slow.class) public class AllFastTests extends AllTests {} March 14, 2011 38
70. What’s next? Quint Buchholz, Mann auf einer Leiter 39
71. What’s next? Updating to more recent JUnit version is easy Old tests will still run New tests will benefit from new features Old tests can be simplified little by little Try it out! March 14, 2011 40
72. What’s next? Updating to more recent JUnit version is easy Old tests will still run New tests will benefit from new features Old tests can be simplified little by little Try it out! March 14, 2011 40
73. Try it out! http://www.junit.org/ https://github.com/marcphilipp/junit-4x-presentation In theory, there is no difference between theory and practice. But, in practice, there is. Jan L. A. van de Snepscheut/Yogi Berra Thank you! Mail marc@andrena.de Twitter @marcphilipp Blog http://marcphilipp.tumblr.com/ March 14, 2011 41