try catch 异常处理场景

Question

I am looking to handle a multi-level error handling scenario, where I have a test looks somehwat like this:

void tester() {
    String fileName = Path.of(myDir, "file_1.lo").toString();
    assertThrows(
            Error.class,
            () -> TheCompilerClass.parent_method_called_by_testcase(fileName),
            "Expected parse error to be thrown for this test"
    );
    assertTrue(getStdErr().contains("Failed to compile"));
}

And this invokes the code I have developed where upon exception I am trying to send back something that will result in bool: True at the assertTrue statement above.

My code structure is like this:

parent_method_called_by_testcase() {
  try {

  } catch (Exception e) {
    System.err.println("Failed to compile ");
    //how do I return the right thing? 
    //STDERR statements can't be returned back to test case invoking methoid?
  }
}

child_method {

  //this finds that exception has occurred and should pass it up the chain
  //should this have a throw statement? or just a return?
  if (exception) {
    tell the parent so that parent can tell the testcase
  }
}

Answer 1

Arguably, log lines like the one you mention are not part of what is generally tested in unit tests. More commonly, we test end functionality. For example, if the child method encounters a case where we throw an exception, does the parent method catch that? In other words, does the parent method throw an exception as well? This is an example of an assertion that one might write in a unit test.

Here, based on your test, your, assertThrows means that you expect the parent method to throw an exception here. So in your catch block, you would do some logging but ultimately throw e if you want the parent to throw if the child does.

parent_method_called_by_testcase() {
  try {
    ...
  } catch (Exception e) {
    System.err.println("Failed to compile ");
    throw e;
  }
}