CSC309 Lecture 11

Software Engineering II
Unit Testing
(202302)

Transcript

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   CSC 309
   Software Engineering II
   Lecture 11: Software Testing
   Dr. Javier Gonzalez-Sanchez
   javiergs@calpoly.edu
   users.csc.calpoly.edu/~javiergs | javiergs.com
   Building 14 -227
   Office Hours: By appointment
   

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   Software Testing
   Unit Testing
   

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   Roadmap
   idea
   requirements
   architecture
   design
   code
   unit testing
   quality measure
   

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   Definition
   Testing a unit - the smallest
   piece of code that can be
   logically isolated in a system.
   (a method in Java)
   

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   Source Code
   

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   Test Case
   

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   JUnit assertion methods
   § Each method can also be passed a string to display if it fails:
   assertTrue(test) fails if the boolean test is false
   assertFalse(test) fails if the boolean test is true
   assertEquals(expected, actual) fails if the values are not equal
   assertSame(expected, actual) fails if the values are not the same (by ==)
   assertNotSame(expected, actual) fails if the values are the same (by ==)
   assertNull(value) fails if the given value is not null
   assertNotNull(value) fails if the given value is null
   fail() causes current test to immediately fail
   

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   Run With Coverage
   

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   Run With Coverage
   

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    ArrayIntList JUnit test
    import org.junit.*;
    import static org.junit.Assert.*;
    public class TestArrayIntList {
    @Test
    public void testAddGet1() {
    ArrayIntList list = new ArrayIntList();
    list.add(42);
    list.add(-3);
    list.add(15);
    assertEquals(42, list.get(0));
    assertEquals(-3, list.get(1));
    assertEquals(15, list.get(2));
    }
    @Test
    public void testIsEmpty() {
    ArrayIntList list = new ArrayIntList();
    assertTrue(list.isEmpty());
    list.add(123);
    assertFalse(list.isEmpty());
    list.remove(0);
    assertTrue(list.isEmpty());
    }
    ...
    

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    Test-Driven Development
    Example
    

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    Definition
    TDD suggests that the code is
    developed or changed exclusively
    on the basis of Unit Testing.
    

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    Test Case
    

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    Source Code
    

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    Run
    

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    Test Case
    

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    Run
    

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    TDD
    

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    Tips for Testing
    § You cannot test every possible input, parameter value, etc.
    So you must think of a limited set of tests likely to expose bugs.
    § Think about boundary cases
    positive; zero; negative numbers
    right at the edge of an array or collection's size
    § Think about empty cases and error cases
    o0, -1, null; an empty list or array
    § Test behavior in combination
    maybe add usually works, but fails after you call to remove
    make multiple calls; maybe the size fails the second time only
    

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    Trustworthy tests
    § Test one thing at a time per test method.
    10 small tests are much better than 1 test 10x as large.
    § Each test method should have a few (likely 1) assert
    statements.
    If you assert many things, since the first that fails will stop the
    test, you won't know whether a later assertion would have
    failed.
    § Tests should avoid logic.
    ominimize if/else, loops, switch, etc.
    § Torture tests are okay, but only in addition to simple tests.
    

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    Tests and Data Structures
    § Need to pass lots of arrays? Use array literals
    public void exampleMethod(int[] values) { ... }
    ...
    exampleMethod(new int[] {1, 2, 3, 4});
    exampleMethod(new int[] {5, 6, 7});
    § Need a quick ArrayList? Try Arrays.asList
    List list = Arrays.asList(7, 4, -2, 3, 9, 18);
    § Need a quick set, queue, etc.? Many collections can take a list
    Set list
    = new HashSet( Arrays.asList(7, 4, -2, 9));
    

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    Questions
    

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    CSC 309
    Software Engineering II
    Lab 11: Unit Testing
    Dr. Javier Gonzalez-Sanchez
    javiergs@calpoly.edu
    users.csc.calpoly.edu/~javiergs | javiergs.com
    Building 14 -227
    Office Hours: By appointment
    

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    Think about this
    Test Cases for your lexer
    Test Cases for your parser
    Implement 6 test cases
    (one per team member)
    

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    Lexer
    class Student{
    Hello x; World w() {}
    Input:
    class
    Student
    {
    Hello
    x
    ;
    Output:
    World
    w
    (
    )
    {
    }
    

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    Empty Class
    class Student{}
    Input:
    Classes: Student
    Relationships:
    Output:
    

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    Clas with Global Variable
    class Student {
    Hello world;
    }
    Input:
    Classes: {Student, Hello}
    Relationships: {{Student, has, Hello}}
    Output:
    

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    Inheritance and Variable
    class Student extends Person{
    Hello world;
    }
    Input:
    Classes: {Student, Person, Hello}
    Relationships:{{ Student, has, Hello}, {Student ,is, Person}}
    Output:
    

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    Inheritance, Method and Local Variable
    class Student extends Person{
    Hello world() {
    Computer c = new Computer();
    }
    }
    Input:
    Classes: {Student, Person, Computer}
    Relationships: {{Student, is, Person}, {Student, uses, Computer}}}
    Output:
    

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    Setup Tutorial
    In case you need it
    

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    PS. You would like to
    a) Create a directory for test cases
    b) Add Junit (version 5 for Java 8 and above)
    

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    Step 1. Select Your Project
    

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    Step 2. Select Your New Folder
    

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    Step 3. Select a Class Name
    

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    Step 4. Generate a Test
    

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    Junit 5
    

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    Step 5. Add Junit Library (if needed)
    

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    Questions
    

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    Let’s Work
    

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    CSC 309 Software Engineering II
    Javier Gonzalez-Sanchez, Ph.D.
    javiergs@calpoly.edu
    Winter 2023
    Copyright. These slides can only be used as study material for the class CSC308 at Cal Poly.
    They cannot be distributed or used for another purpose.
    

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