public void test_hyphenNotOk() throws Exception {
String code = "$a-b = 10";
XtextResource r = getResourceFromString(code);
AssertableDiagnostics asserter = tester.validate(r.getContents().get(0));
asserter.assertAny(
AssertableDiagnostics.errorCode(IPPDiagnostics.ISSUE__NOT_ASSIGNABLE),
AssertableDiagnostics.errorCode(IPPDiagnostics.ISSUE__NOT_NUMERIC));
resourceWarningDiagnostics(r).assertDiagnostic(IPPDiagnostics.ISSUE__UNKNOWN_VARIABLE);
resourceErrorDiagnostics(r).assertOK();
}