Fixed a bug where multiple when entries could execute in one statement.

translator/src/org/jetbrains/k2js/translate/WhenTranslator.java

@@ -91,7 +91,7 @@ public class WhenTranslator extends AbstractTranslator {
             return statementToExecute;
         }
         JsExpression condition = translateConditions(entry);
-        return new JsIf(condition, statementToExecute, null);
+        return new JsIf(condition, addDummyBreak(statementToExecute), null);
     }
 
     @NotNull
@@ -119,6 +119,11 @@ public class WhenTranslator extends AbstractTranslator {
         throw new AssertionError("Unsupported when condition " + condition.getClass());
     }
 
+    @NotNull
+    private JsBlock addDummyBreak(@NotNull JsStatement statement) {
+        return AstUtil.newBlock(statement, new JsBreak());
+    }
+
 
     @NotNull
     private JsExpression translatePatternCondition(@NotNull JetWhenConditionIsPattern condition) {

translator/test/org/jetbrains/k2js/test/PatternMatchingTest.java

@@ -24,4 +24,9 @@ public final class PatternMatchingTest extends IncludeLibraryTest {
         testFooBoxIsTrue("whenNotType.kt");
     }
 
+    @Test
+    public void whenExecutesOnlyOnce() throws Exception {
+        testFooBoxIsTrue("whenExecutesOnlyOnce.kt");
+    }
+
 }

translator/testFiles/patternMatching/cases/whenExecutesOnlyOnce.kt

@@ -0,0 +1,15 @@
+namespace foo
+
+class A() {
+
+}
+
+fun box() : Boolean {
+  var a = 0
+  when(A()) {
+    is A => a++;
+    is A => a++;
+    else => a++;
+  }
+  return (a == 1)
+}