ExpectedException drastically simplified

Signed-off-by: Kent Beck <kent@threeriversinstitute.org>
narasimha · Jun 2, 2009 · a423117 · a423117
1 parent 3f05aac
commit a423117
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Showing 3 changed files with 71 additions and 45 deletions.
diff --git a/src/main/java/org/junit/experimental/interceptor/ExpectedException.java b/src/main/java/org/junit/experimental/interceptor/ExpectedException.java
@@ -1,30 +1,36 @@
 package org.junit.experimental.interceptor;
 
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.hamcrest.CoreMatchers.instanceOf;
+import org.hamcrest.FeatureMatcher;
+import org.hamcrest.Matcher;
+import org.hamcrest.StringDescription;
+import org.junit.Assert;
 import org.junit.runners.model.FrameworkMethod;
 import org.junit.runners.model.Statement;
 
 public class ExpectedException implements StatementInterceptor {
-	private Class<? extends Throwable> fType;
-	private String fMessage;
+	private Matcher<Throwable> fMatcher= null;
 
 	public Statement intercept(Statement base, FrameworkMethod method) {
 		return new ExpectedExceptionStatement(base);
 	}
 
+	// TODO (Jun 1, 2009 3:56:50 PM): expect multiple things
+	// TODO (Jun 1, 2009 4:26:59 PM): expect on original throwable
 	public void expect(Class<? extends Throwable> type) {
-		fType= type;
+		fMatcher= instanceOf(type);
 	}
 
-	public void expectMessage(String message) {
-		fMessage= message;
+	public void expectMessage(String substring) {
+		expectMessage(containsString(substring));
 	}
 
-	private boolean noExpectedException() {
-		return fType == null && fMessage == null;
+	public void expectMessage(Matcher<String> matcher) {
+		fMatcher= hasMessage(matcher);
 	}
-
-	public class ExpectedExceptionStatement extends Statement {
 
+	private class ExpectedExceptionStatement extends Statement {
 		private final Statement fNext;
 
 		public ExpectedExceptionStatement(Statement base) {
@@ -33,42 +39,27 @@ public ExpectedExceptionStatement(Statement base) {
 
 		@Override
 		public void evaluate() throws Throwable {
-			boolean complete = false;
 			try {
 				fNext.evaluate();
-				complete = true;
 			} catch (Throwable e) {
-				if (noExpectedException())
+				if (fMatcher == null)
 					throw e;
-				// TODO (May 26, 2009 11:46:31 PM): isInstance?
-				if (fType != null && !fType.isAssignableFrom(e.getClass())) {
-					String message= "Unexpected exception, expected<"
-								+ fType.getName() + "> but was<"
-								+ e.getClass().getName() + ">";
-					throw new Exception(message, e);
-				}
-				if (fMessage != null && !getMessage(e).contains(fMessage)) {
-					String message= "Unexpected exception message, expected<"
-								+ fMessage + "> but was<"
-								+ getMessage(e) + ">";
-					throw new Exception(message, e);
-				}
-			}
-			// TODO (May 26, 2009 11:54:22 PM): do I need complete
-			if (complete && !noExpectedException()) {
-				if (fType != null)
-					throw new AssertionError("Expected exception: "
-							+ fType.getName());
-				else if (fMessage != null)
-					throw new AssertionError("Expected exception with message: "
-							+ fMessage);
-				else
-					throw new RuntimeException("How'd we get here?");
+				Assert.assertThat(e, fMatcher);
+				return;
 			}
+			if (fMatcher != null)
+				throw new AssertionError("Expected test to throw "
+						+ StringDescription.toString(fMatcher));
 		}
+	}
 
-		private String getMessage(Throwable e) {
-			return e.getMessage() == null ? "" : e.getMessage();
-		}
+	private Matcher<Throwable> hasMessage(Matcher<String> matcher) {
+		return new FeatureMatcher<Throwable, String>(matcher,
+				"exception with message", "getMessage()") {
+			@Override
+			protected String featureValueOf(Throwable actual) {
+				return actual.getMessage();
+			}
+		};
 	}
 }
diff --git a/src/main/java/org/junit/internal/runners/statements/ExpectException.java b/src/main/java/org/junit/internal/runners/statements/ExpectException.java
@@ -5,7 +5,6 @@
 
 import org.junit.runners.model.Statement;
 
-
 public class ExpectException extends Statement {
 	private Statement fNext;
 	private final Class<? extends Throwable> fExpected;

diff --git a/src/test/java/org/junit/tests/experimental/interceptor/ExpectedExceptionInterceptorTest.java b/src/test/java/org/junit/tests/experimental/interceptor/ExpectedExceptionInterceptorTest.java
@@ -1,12 +1,15 @@
 package org.junit.tests.experimental.interceptor;
 
+import static org.hamcrest.CoreMatchers.startsWith;
 import static org.junit.Assert.assertThat;
 import static org.junit.experimental.results.PrintableResult.testResult;
 import static org.junit.experimental.results.ResultMatchers.hasSingleFailureContaining;
 import static org.junit.experimental.results.ResultMatchers.isSuccessful;
 import org.junit.Test;
 import org.junit.experimental.interceptor.ExpectedException;
 import org.junit.experimental.interceptor.Interceptor;
+import org.junit.runners.model.FrameworkMethod;
+import org.junit.runners.model.Statement;
 
 public class ExpectedExceptionInterceptorTest {
 	public static class HasExpectedException {
@@ -52,7 +55,7 @@ public void throwsNullPointerException() {
 	public void unExpectedExceptionFails() {
 		assertThat(
 				testResult(HasWrongExpectedException.class),
-				hasSingleFailureContaining("Unexpected exception, expected<java.lang.NullPointerException> but was<java.lang.IllegalArgumentException>"));
+				hasSingleFailureContaining("Expected: an instance of java.lang.NullPointerException"));
 	}
 
 	public static class HasWrongMessage {
@@ -70,7 +73,7 @@ public void throwsNullPointerException() {
 	public void wrongMessageFails() {
 		assertThat(
 				testResult(HasWrongMessage.class),
-				hasSingleFailureContaining("Unexpected exception message, expected<expectedMessage> but was<actualMessage>"));
+				hasSingleFailureContaining("\"expectedMessage\"\n     but: getMessage() was \"actualMessage\""));
 	}
 
 	public static class WronglyExpectsException {
@@ -87,7 +90,7 @@ public void doesntThrowNullPointerException() {
 	public void failsIfExceptionNeverComes() {
 		assertThat(
 				testResult(WronglyExpectsException.class),
-				hasSingleFailureContaining("Expected exception: java.lang.NullPointerException"));
+				hasSingleFailureContaining("Expected test to throw an instance of java.lang.NullPointerException"));
 	}
 
 	public static class WronglyExpectsExceptionMessage {
@@ -104,7 +107,7 @@ public void doesntThrowAnything() {
 	public void failsIfExceptionMessageNeverComes() {
 		assertThat(
 				testResult(WronglyExpectsExceptionMessage.class),
-				hasSingleFailureContaining("Expected exception with message: anything!"));
+				hasSingleFailureContaining("Expected test to throw exception with message a string containing \"anything!\""));
 	}
 
 	public static class ExpectsSubstring {
@@ -139,6 +142,39 @@ public void throwsMore() {
 	public void failsWithNullExceptionMessage() {
 		assertThat(
 				testResult(ExpectsSubstringNullMessage.class),
-				hasSingleFailureContaining("Unexpected exception message, expected<anything!> but was<>"));
+				hasSingleFailureContaining("but: getMessage() was null"));
+	}
+
+	public static class ExpectsMatcher {
+		@Interceptor
+		public ExpectedException thrown= new ExpectedException();
+
+		@Test
+		public void throwsMore() {
+			thrown.expectMessage(startsWith("Ack"));
+			throw new NullPointerException("Ack!");
+		}
+	}
+
+	@Test
+	public void succeedsWithMatcher() {
+		assertThat(testResult(ExpectsMatcher.class), isSuccessful());
+	}
+
+	public static class ExpectsMatcherFails {
+		@Interceptor
+		public ExpectedException thrown= new ExpectedException();
+
+		@Test
+		public void throwsMore() {
+			thrown.expectMessage(startsWith("Wrong start"));
+			throw new NullPointerException("Back!");
+		}
+	}
+
+	@Test
+	public void failsWithMatcher() {
+		assertThat(testResult(ExpectsMatcherFails.class),
+				hasSingleFailureContaining("Wrong start"));
 	}
 }