Add ability to test for expected errors in intentions

If an intention test contains `// SHOULD_FAIL_WITH: my_string`, the test
is expected to throw `IntentionTestException("my_string")`. This is
useful for testing whether or not a function that should be called, is
called (a pop-up dialog is displayed, etc.).

idea/tests/org/jetbrains/jet/plugin/intentions/AbstractCodeTransformationTest.java

@@ -170,9 +170,19 @@ public abstract class AbstractCodeTransformationTest extends LightCodeInsightTes
                 "isAvailable() for " + intentionAction.getClass() + " should return " + isApplicableExpected,
                 isApplicableExpected == intentionAction.isAvailable(getProject(), getEditor(), getFile()));
 
-        if (isApplicableExpected) {
+        String shouldFailString = InTextDirectivesUtils.findStringWithPrefixes(fileText, "// SHOULD_FAIL_WITH: ");
-            intentionAction.invoke(getProject(), getEditor(), getFile());
+
-            checkResultByFile(path + ".after");
+        try {
+            if (isApplicableExpected) {
+                intentionAction.invoke(getProject(), getEditor(), getFile());
+                // Don't bother checking if it should have failed.
+                if (shouldFailString == null) {
+                    checkResultByFile(path + ".after");
+                }
+            }
+            assertNull("Expected test to fail.", shouldFailString);
+        } catch (IntentionTestException e) {
+            assertEquals("Failure message mismatch.", shouldFailString, e.getMessage());
         }
     }
 

idea/tests/org/jetbrains/jet/plugin/intentions/IntentionTestException.kt

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.plugin.intentions;
+
+public class IntentionTestException(message: String): RuntimeException(message)