test(WarningsTest): add cases for interface/abstract/native throws

Author: xdavidwu

src/test/examples/maven-project/src/org/javacs/warn/Unused.java

@@ -44,4 +44,14 @@ void referenceUsedByUnusedVar() {
     }
 
     void notActuallyThrown() throws Exception { }
-}
+
+    interface Throws {
+        void interfaceThrows() throws Exception;
+    }
+
+    abstract class AbstractThrows {
+        abstract void abstractThrows() throws Exception;
+    }
+
+    native void nativeThrows() throws Exception;
+}

src/test/java/org/javacs/WarningsTest.java

@@ -93,6 +93,9 @@ public void unused() {
         assertThat(errors, hasItem("unused_method(34)")); // private void unusedMutuallyRecursive2() { ... }
         assertThat(errors, not(hasItem("unused_method(38)"))); // private int usedByUnusedVar() { ... }
         assertThat(errors, hasItem("unused_throws(46)")); // void notActuallyThrown() throws Exception { }
+        assertThat(errors, not(hasItem("unused_throws(49)"))); // void interfaceThrows() throws Exception;
+        assertThat(errors, not(hasItem("unused_throws(53)"))); // abstract void abstractThrows() throws Exception;
+        assertThat(errors, not(hasItem("unused_throws(56)"))); // native void nativeThrows() throws Exception;
     }
 
     @Test