cse15l-lab-reports

Week 3 Lab Report: Servers and Bugs

Part 1

The following is a screenshot of the code for my StringServer

Here are two examples of using /add-message

• The method handleRequest is called with the argument new URI("localhost:4000/add-message?s=Hello")
• The String s changed from the empty string "" to "\nHello" after this request

• The method handleRequest is called with the argument new URI("localhost:4000/add-message?s=How%20are%20you%20")
• The String s changed from "\nHello" to "\nHello\nHow are you" after this request

Part 2

In lab 3, there was a bug in the merge method in ListExamples.java.

This is an example of a failure-inducing input for the buggy program

@Test
public void testMerge() {
    String[] input1Array = {"a", "a", "c"};
    List<String> input1 = Arrays.asList(input1Array);
    String[] input2Array = {"d", "z", "z"};
    List<String> input2 = Arrays.asList(input2Array);
    String[] expectedArray = {"a", "a", "c", "d", "z", "z"};
    List<String> expected = Arrays.asList(expectedArray);
    List<String> actual = ListExamples.merge(input1, input2);
    assertEquals(expected, actual);
}

Here is the symptom of this failed test

This is an example of an input that doens’t induce a failure

@Test
public void testMergeEmpty() {
    List<String> input1 = new ArrayList<>();
    List<String> input2 = new ArrayList<>();
    List<String> expected = new ArrayList<>();
    List<String> actual = ListExamples.merge(input1, input2);
    assertEquals(expected, actual);
}

Here is the output of running this test

In the last while loop of the merge method, there was a line that said

index1 += 1;

instead of

index2 += 1;

Changing this line fixes the issue because initially, the code incremented index1 instead of index2. This caused the while loop to be always true, resulting in an infinite loop.

Part 3

My most important takeaway is the importance of testing your code thoroughly. It’s not always obvious that your program has a bug because a bug won’t result in an error in every single test case. Sometimes you may write a few test cases that all pass, but there could be a few edge cases that you didn’t consider.