@Test
@DisplayName("check mapping expression to be SUBTYPE for regular mapping in TSTargetDeclType")
void conversionCoverage() {

    TypeMappingExpression expr = CustomMappingParserFactory.parser().parse("String->sting").orElse(null);
    TSTargetDeclType testee = new TSTargetDeclType(expr,new HashMap<>(),false);
    assertEquals(testee.conversionCoverage(),SUBTYPES);
}