test/com/google/javascript/jscomp/TypeCheckTest.java
/**
   * Tests that undefined can be compared shallowly to a value of type (number,undefined) regardless
   * of the side on which the undefined value is.
   */
Tests that undefined can be compared shallowly to a value of type (number,undefined) regardless
of the side on which the undefined value is.
Tests that undefined can be compared shallowly to a value of type ( number undefined ) regardless of the side on which the undefined value is .
@Test
  public void testBug901455b() {
    testTypes("/** @return {(number|undefined)} */ function a() { return 3; }" +
        "var b = a() === undefined");
  }
@ Test public void testBug901455b ( ) { testTypes ( "/** @return {(number|undefined)} */ function a() { return 3; }" + "var b = a() === undefined" ) ; }
Tests that undefined can be compared shallowly to a value of type (number,undefined) regardless
 of the side on which the undefined value is.
Tests that undefined can be compared shallowly to a value of type ( number undefined ) regardless of the side on which the undefined value is .