2021 KCDC JUnit 5

Intro to JUnit 5

Transcript

1. @jeanneboyarsky 1
   Intro to Testing with JUnit 5
   Jeanne Boyarsky
   
   
   Sept 17, 2021
   
   
   KCDC
   
   
   speakerdeck.com/boyarsky
   
   
   

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2. @jeanneboyarsky 2
   Change
   this report to add a field?
   No problem! Wait. What is this
   supposed to do?
   

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3. @jeanneboyarsky 3
   This
   is taking so long. Ok got it.
   My customers will be happy
   now.
   

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4. @jeanneboyarsky 4
   The
   numbers on the report are
   wrong. How could you let this
   happen!!!?
   

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5. @jeanneboyarsky 5
   Uh oh.
   
   
   I wish I had used JUnit!
   

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6. @jeanneboyarsky
   • JUnit 5?
   
   
   • JUnit 4?
   
   
   • None
   
   
   6
   

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7. @jeanneboyarsky
   About Me
   • Java Champion
   
   
   • Author
   
   
   • Developer at NYC
   bank for 19+
   years
   
   
   • FIRST Robotics
   Mentor
   7
   

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8. @jeanneboyarsky
   Pause for a Commercial
   8
   Java certs
   
   
   •Java 8
   
   
   •Java 11
   
   
   •Java 17 next
   
   
   Book giveaway at end!
   

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9. @jeanneboyarsky
   Another Commercial
   9
   

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10. @jeanneboyarsky
    After this presentation
    • Presentation:
    
    
    http://speakerdeck.com/
    boyarsky
    
    
    • Samples and code we write
    together:
    
    
    https://github.com/boyarsky/
    2021-kcdc-junit5
    10
    

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11. @jeanneboyarsky
    Agenda
    ⭐ Intro to JUnit 5
    
    
    • Common testing patterns
    
    
    • Brief look back at history
    
    
    (JUnit 3 and 4)
    
    
    • JUnit 5 extensions
    
    
    • Interactive TDD live coding
    11
    

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12. @jeanneboyarsky
    • Released Sept 10,
    2017
    
    
    • Requires Java 8
    
    
    • Today sprinkling in
    Java 9+ features
    12
    

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13. @jeanneboyarsky
    Basic Flow
    13
    class ReportTest
    {
    
    private Report report
    ;
    
    @BeforeEac
    h
    
    void setUp()
    {
    
    report = new Report()
    ;
    
    }
    
    @Tes
    t
    
    void createRow()
    {
    
    }
    
    }
    
    No need to
    
    
    make public
    Runs before
    
    
    each test
    Can have 1+ tests
    

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14. @jeanneboyarsky
    Common Class name patterns
    14
    Unit Tests Integration Tests
    Test*.java IT*.java
    *Test.java *IT.java
    *Tests.java *ITCase.java
    *TestCase.java
    

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15. @jeanneboyarsky
    Common test name examples
    15
    Method names
    testCreateRow()
    createRow()
    createRow_forNullParams()
    shouldHandleNullParams()
    

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16. @jeanneboyarsky
    Assert Equals
    16
    @Tes
    t
    
    void createRow()
    {
    
    String expected =
    
    
    "Jeanne Boyarsky,Intro to JUnit 5"
    ;
    
    String actual = report.createRow
    (
    
    "Jeanne Boyarsky", "Intro to JUnit 5")
    ;
    
    assertEquals(expected, actual, "row")
    ;
    
    }
    
    Optional message
    Order matters
    

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17. @jeanneboyarsky
    Message on failing assert
    17
    row ==> expected:
    
    
    but was: >
    
    Expected :Jeanne Boyarsk
    y
    
    Actual :Jeanne Boyarsky,Intro to JUnit 5
    Remember that order matters!
    Message
    

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18. @jeanneboyarsky
    BeforeAll
    18
    class ReportWithCacheTest
    {
    
    private static Map CACHE
    ;
    
    private ReportWithCache report
    ;
    
    @BeforeAl
    l
    
    static void createCache()
    {
    
    CACHE = Map.of("Intro to JUnit 5”
    ,
    
    "Jeanne Boyarsky")
    ;
    
    }
    
    @BeforeEac
    h
    
    void setUp()
    {
    
    report = new ReportWithCache(CACHE)
    ;
    
    }
    Runs once
    static
    

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19. @jeanneboyarsky
    BeforeAll
    19
    @Tes
    t
    
    void createRow_match()
    {
    
    String expected =
    
    
    "Jeanne Boyarsky,Intro to JUnit 5"
    ;
    
    String actual = report.createRow
    (
    
    "Intro to JUnit 5")
    ;
    
    assertEquals(expected, actual, "row")
    ;
    
    }
    
    @Tes
    t
    
    void createRow_noMatch()
    {
    
    String expected = "Unknown,Lunch"
    ;
    
    String actual = report.createRow("Lunch")
    ;
    
    assertEquals(expected, actual, "default value")
    ;
    
    }
    
    @BeforeEach runs twice
    
    
    @BeforeAll runs once
    

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20. @jeanneboyarsky
    Review: fill in the blanks
    20
    class BlanksTest {
    private String z
    ;
    
    @_________
    _
    
    static void a() {
    
    
    // lookup next i
    d
    
    }
    @_________
    _
    
    static void b() { Target.cache.clear(); }
    @_________
    _
    
    void c() { z = “test data"; }
    @_________
    _
    
    void d() { z = null; }
    @___
    _
    
    void e() { assertNotNull(z); }
    }
    
    BeforeAll
    AfterAll
    BeforeEach
    AfterEach
    Test
    

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21. @jeanneboyarsky
    Review: what is output?
    21
    class FlowTest {
    private static String flow = "";
    @BeforeAl
    l
    
    static void before() { flow+="x"; }
    @AfterAl
    l
    
    static void after() { System.out.println(flow); }
    @BeforeEac
    h
    
    void setUp() { flow+="y"; }
    @AfterEac
    h
    
    void tearDown() { flow+="-"; }
    @Tes
    t
    
    void one() { flow+="z"; }
    @Tes
    t
    
    void two() { flow+="z"; }
    }
    
    xyz-yz-
    

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22. @jeanneboyarsky
    How about now?
    22
    class FlowTest {
    private static String flow = "";
    @BeforeAl
    l
    
    static void before() { flow+="x"; }
    @AfterAl
    l
    
    static void after() { System.out.println(flow); }
    @BeforeEac
    h
    
    void setUp() { flow+="y"; }
    @AfterEac
    h
    
    void tearDown() { flow+="-"; }
    @Tes
    t
    
    void one() { flow+="1"; }
    @Tes
    t
    
    void two() { flow+="2"; }
    }
    
    “deterministic but
    non-obvious” order
    
    
    do not rely on it
    

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23. @jeanneboyarsky
    If you really need order
    23
    @TestMethodOrder(MethodOrderer.OrderAnnotation.class
    )
    
    class OrderedFlowTest
    {
    
    private static String flow = ""
    ;
    
    @AfterAl
    l
    
    static void after(){ System.out.println(flow); }
    @Tes
    t
    
    @Order(1
    )
    
    void one() { flow+="1"; }
    @Tes
    t
    
    @Order(2
    )
    
    void two() { flow+="2"; }
    }
    
    12
    
    
    Are you *sure* you
    need order?
    

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24. @jeanneboyarsky
    Assertions without Lambdas
    24
    assertTrue assertEquals assertIterableEquals
    assertFalse assertNotEquals assertLinesMatch
    assertNull assertArrayEquals assertSame
    assertNotNull assertNotSame
    

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25. @jeanneboyarsky
    Assert Examples
    25
    assertNotNull(“")
    ;
    
    assertTrue(“".isEmpty())
    ;
    
    assertNotSame("", new String(“"))
    ;
    
    assertLinesMatch(List.of("xyz"),
    
    
    Arrays.asList("xyz"))
    ;
    
    All have optional last
    parameter with message
    

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26. @jeanneboyarsky
    Review: fill in the blanks
    26
    @Tes
    t
    
    void asserts()
    {
    
    String message = "sum"
    ;
    
    int sum = Adder.sum(1, 2, 3)
    ;
    
    ______________(sum == 6)
    ;
    
    _______________(_____, _______, __________)
    ;
    
    }
    
    assertEquals
    assertTrue
    6 sum message
    

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27. @jeanneboyarsky
    assertTrue vs assertEquals
    27
    org.opentest4j.AssertionFailedError:
    
    
    expected: but was:
    org.opentest4j.AssertionFailedError:
    
    
    sum ==> expected: <6> but was: <7>
    Use most specific
    assertion you can
    

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28. @jeanneboyarsky
    Agenda
    ✅ Intro to JUnit 5
    
    
    ⭐ Common testing patterns
    
    
    • Brief look back at history
    
    
    (JUnit 3 and 4)
    
    
    • JUnit 5 extensions
    
    
    • Interactive TDD live coding
    28
    

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29. @jeanneboyarsky
    assertThrows
    29
    @Tes
    t
    
    void throwsException()
    {
    
    assertThrows(IllegalArgumentException.class,
    
    
    () -> Exceptions.validate(null))
    ;
    
    }
    
    org.opentest4j.AssertionFailedError:
    
    
    Expected java.lang.IllegalArgumentException to be thrown,
    
    
    but nothing was thrown.
    

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30. @jeanneboyarsky
    Which Better?
    30
    @Tes
    t
    
    void throwsException()
    {
    
    assertThrows(IllegalArgumentException.class,
    
    
    () -> Exceptions.validate(null))
    ;
    
    }
    
    @Tes
    t
    
    void message()
    {
    
    IllegalArgumentException actual =
    
    
    assertThrows(IllegalArgumentException.class,
    
    
    () -> Exceptions.validate(null))
    ;
    
    assertEquals("str can't be null",
    
    
    actual.getMessage())
    ;
    
    }
    
    

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31. @jeanneboyarsky
    assertTimeout
    31
    @Tes
    t
    
    void tooLong()
    {
    
    assertTimeout(Duration.ofSeconds(2),
    
    
    this::sketchyCode)
    ;
    
    }
    
    private void sketchyCode()
    {
    
    try
    {
    
    Thread.sleep(5_000)
    ;
    
    } catch (InterruptedException e)
    {
    
    // ignor
    e
    
    }
    
    }
    
    org.opentest4j.AssertionFailedError:
    
    
    execution exceeded timeout of 2000 ms by 3005 ms
    

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32. @jeanneboyarsky
    assertAll - groups
    32
    @Tes
    t
    
    void bean()
    {
    
    Bean bean = new Bean("J", "B")
    ;
    
    assertAll("name"
    ,
    
    () -> assertEquals("Jeanne",
    
    
    bean.getFirstName(), "first")
    ,
    
    () -> assertEquals("Boyarsky",
    
    
    bean.getLastName(), "last"))
    ;
    
    }
    
    DefaultMultiCauseException: name (2 failures)
    
    
    org.opentest4j.AssertionFailedError: first ==>
    
    
    expected: but was:
    
    
    org.opentest4j.AssertionFailedError: last ==>
    
    
    expected: but was:
    

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33. @jeanneboyarsky
    Side note - records
    33
    public record Record (String firstName,
    
    
    String lastName) { }
    @Tes
    t
    
    void record()
    {
    
    Record record = new Record("J", "B")
    ;
    
    Record expected = new Record
    (
    
    “Jeanne", "Boyarsky")
    ;
    
    assertEquals(expected, record, "name")
    ;
    
    }
    
    org.opentest4j.AssertionFailedError: name ==> expected:
    but was:
    
    

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34. @jeanneboyarsky
    assertAll - dependencies
    34
    @Tes
    t
    
    void bean()
    {
    
    Bean bean = null
    ;
    
    assertAll("found name”
    ,
    
    () ->
    {
    
    assertNotNull(bean)
    ;
    
    assertAll("name values"
    ,
    
    () -> assertEquals("Jeanne",
    
    
    bean.getFirstName(), "first")
    ,
    
    () -> assertEquals("Boyarsky",
    
    
    bean.getLastName(), "last"))
    ;
    
    })
    ;
    
    }
    
    org.opentest4j.AssertionFailedError: expected: not
    
    
    org.opentest4j.MultipleFailuresError: found name (1 failure)
    
    
    org.opentest4j.AssertionFailedError: expected: not
    Doesn’t run
    inner assertAll
    semicolons
    because
    lambda blocks
    

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35. @jeanneboyarsky
    Assuming
    35
    @Tes
    t
    
    void bean()
    {
    
    Bean bean = null
    ;
    
    assumeFalse(bean == null, "no name")
    ;
    
    assertEquals("Jeanne",
    
    
    bean.getFirstName(), "first")
    ;
    
    assertEquals("Boyarsky",
    
    
    bean.getLastName(), "last")
    ;
    
    }
    
    Reports test is ignored Remember - simplest
    approach is best
    

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36. @jeanneboyarsky
    Assumptions
    36
    Annotation Parameters
    assumeTrue boolean or BooleanSupplier
    
    
    optional message
    assumeFalse boolean or BooleanSupplier
    
    
    optional message
    assumingThat boolean or BooleanSupplier
    
    
    Executable
    
    
    (runs the Executable only
    
    
    if the assumption is true)
    

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37. @jeanneboyarsky
    Running only on Linux
    37
    @Tes
    t
    
    void packagedOnServer()
    {
    
    assumeTrue(System.getProperty(“os.name"
    )
    
    .toLowerCase().contains("linux"),
    
    
    "skip if not linux")
    ;
    
    // assertions her
    e
    
    }
    
    @Tes
    t
    
    @EnabledOnOs(OS.LINUX
    )
    
    void linuxAnnotation()
    {
    
    // assertions her
    e
    
    }
    
    Simplest approach is
    still best
    Also reports as
    ignored
    

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38. @jeanneboyarsky
    OS Annotations
    38
    Annotations
    EnabledOnOS
    DisabledOnOS
    @EnabledOnOs(LINUX
    )
    
    @EnabledOnOs({OS.LINUX, OS.MAC }
    )
    
    OS
    WINDOWS AIX
    MAC SOLARIS
    LINUX OTHER
    

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39. @jeanneboyarsky
    Disabling Entirely
    39
    @Disable
    d
    
    @Tes
    t
    
    void uhOh()
    {
    
    // assertions her
    e
    
    }
    
    Also reports as ignored
    

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40. @jeanneboyarsky
    Display Names
    40
    @DisplayName("Requirement 123"
    )
    
    class DisplayNameTest
    {
    
    @Tes
    t
    
    @DisplayName("use case 1"
    )
    
    void negativeNumber()
    {
    
    }
    
    }
    
    

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41. @jeanneboyarsky
    Tags & Build Tools
    41
    @Tag("slow"
    )
    
    class TagTest
    {
    
    @Tes
    t
    
    @Tag("full-suite"
    )
    
    void test()
    {
    
    }
    
    }
    
    test
    {
    
    useJUnitPlatform {
    excludeTags 'slow', 'abc
    '
    
    }
    }
    
    >
    
    >
    
    maven-surefire-plugi
    n
    
    >
    
    >
    
    slow>
    
    >
    
    >
    
    

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42. @jeanneboyarsky
    Tags in the IDE
    42
    

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43. @jeanneboyarsky
    Repeated Test
    43
    @RepeatedTest(100
    )
    
    void threadsDoNotFail()
    {
    
    }
    
    Runs 100 times.
    
    
    Fails test if any fail
    

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44. @jeanneboyarsky
    Testing System.out.println
    44
    class HelloWorldTest
    {
    
    private PrintStream originalSystemOut
    ;
    
    private ByteArrayOutputStream mockSystemOut
    ;
    
    @BeforeEac
    h
    
    void setUp()
    {
    
    mockSystemOut = new ByteArrayOutputStream()
    ;
    
    System.setOut(new PrintStream(mockSystemOut))
    ;
    
    }
    
    @AfterEac
    h
    
    void restoreSystemOut()
    {
    
    System.setOut(originalSystemOut)
    ;
    
    }
    
    @Tes
    t
    
    void prints()
    {
    
    HelloWorld.main()
    ;
    
    String actual = mockSystemOut.toString()
    ;
    
    assertEquals("Hello World", actual.strip())
    ;
    
    }
    }
    
    Warning: be
    careful if running
    multi-threaded
    

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45. @jeanneboyarsky
    Agenda
    ✅ Intro to JUnit 5
    
    
    ✅ Common testing patterns
    
    
    ⭐ Brief look back at history
    
    
    (JUnit 3 and 4)
    
    
    • JUnit 5 extensions
    
    
    • Interactive TDD live coding
    45
    

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46. @jeanneboyarsky 46
    JUnit 3.X JUnit 4.X JUnit 5.X
    Released ? 2006 2017
    Superclass TestCase No No
    Package junit
    
    
    .framework
    org.junit org.junit
    
    
    .jupiter….
    Minimum
    
    
    Java version
    ? 5 8
    

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47. @jeanneboyarsky 47
    JUnit 3.X JUnit 4.X JUnit 5.X
    assertEquals [message,]
    
    
    expected,
    
    
    actual
    [message,]
    
    
    expected,
    
    
    actual
    expected,
    
    
    actual
    
    
    [,message]
    Setup method
    
    
    name
    setUp() any any
    Access
    
    
    control
    public public package
    
    
    private or
    
    
    higher
    

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48. @jeanneboyarsky 48
    JUnit 3.X JUnit 4.X JUnit 5.X
    Test names test* Any Any
    Skipping a
    
    
    test
    Comment
    
    
    it out
    @Ignore @Disabled
    

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49. @jeanneboyarsky
    Agenda
    ✅ Intro to JUnit 5
    
    
    ✅ Common testing patterns
    
    
    ✅ Brief look back at history
    
    
    (JUnit 3 and 4)
    
    
    ⭐ JUnit 5 extensions
    
    
    • Interactive TDD live coding
    49
    

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50. @jeanneboyarsky
    Parameterized Tests
    50
    Dependenc
    y
    
    testImplementatio
    n
    
    'org.junit.jupiter:junit-jupiter-params:5.7.2
    '
    
    enum Env { DEV, QA, PROD}
    ;
    
    @ParameterizedTes
    t
    
    @EnumSource(Env.class
    )
    
    void byEnum(Env env)
    {
    
    }
    
    

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51. @jeanneboyarsky
    Parameterized Tests
    51
    @ParameterizedTes
    t
    
    @ValueSource(strings = { "SpaceX", "Boeing"}
    )
    
    void byValue(String company)
    {
    
    }
    
    Supports all primitives, strings, and classes
    

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52. @jeanneboyarsky
    Parameterized Tests
    52
    static Stream data()
    {
    
    return Stream.generate
    (
    
    () -> Math.random()).limit(10)
    ;
    
    }
    
    @ParameterizedTes
    t
    
    @MethodSource("data"
    )
    
    void byMethod(Double number)
    {
    
    }
    
    @ParameterizedTes
    t
    
    @MethodSource("com.jeanneboyarsky.kcdc.junit5."
    +
    
    "extensions.Enabled#getEnabled"
    )
    
    void byMethodElsewhere(String name)
    {
    
    }
    
    

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53. @jeanneboyarsky
    Retry Failed Tests
    53
    Dependenc
    y
    
    testImplementation
    
    
    ‘io.github.artsok:rerunner-jupiter:2.1.6
    '
    
    @RepeatedIfExceptionsTest(repeats = 3
    )
    
    void flakeyTest()
    {
    
    throw new RuntimeException("Uh oh")
    ;
    
    }
    
    @RepeatedIfExceptionsTest(repeats = 3
    )
    
    void goodTest() {
    }
    
    @ParameterizedRepeatedIfExceptionsTes
    t
    
    @ValueSource(ints = {1,2,3}
    )
    
    void params(int num) {
    }
    
    

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54. @jeanneboyarsky
    Hamcrest Matchers
    54
    Dependenc
    y
    
    testImplementation 'org.hamcrest:hamcrest-library:2.2
    '
    
    import org.junit.jupiter.api.Test
    ;
    
    import static org.hamcrest.CoreMatchers.containsString
    ;
    
    import static org.hamcrest.MatcherAssert.assertThat
    ;
    
    public class HamcrestTest
    {
    
    @Tes
    t
    
    void matcher()
    {
    
    assertThat("kc", containsString("kc"))
    ;
    
    }
    
    }
    
    

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55. @jeanneboyarsky
    Common Matchers
    55
    Type Examples
    Combiners anyOf, allOf, both, either
    Lists hasItem, is
    By type any
    Equality equalTo, nullValue, notNull,
    
    
    containsString, startsWith,
    
    
    endsWith
    

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56. @jeanneboyarsky
    Mockito
    56
    Dependenc
    y
    
    testImplementation 'org.mockito:mockito-junit-jupiter:3.12.1
    '
    
    testImplementation 'org.mockito:mockito-core:3.12.1
    '
    
    @ExtendWith(MockitoExtension.class
    )
    
    public class MockingTest
    {
    
    private Processor processor
    ;
    
    @Moc
    k
    
    Function functionMock
    ;
    
    @BeforeEac
    h
    
    void setUp()
    {
    
    processor = new Processor(functionMock)
    ;
    
    }
    
    

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57. @jeanneboyarsky
    Mockito
    57
    @Tes
    t
    
    void process()
    {
    
    String text = "abc"
    ;
    
    int expected = 42
    ;
    
    when(functionMock.apply(text)
    )
    
    .thenReturn(expected)
    ;
    
    int actual = processor.process(text)
    ;
    
    assertEquals(expected, actual, "result")
    ;
    
    verify(functionMock, times(1)).apply(text)
    ;
    
    }
    
    }
    
    

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58. @jeanneboyarsky
    Common Verifiers
    58
    Examples
    atLeastOnce(), atLeast(int)
    atMostOnce(), atMost()
    times()
    never()
    Also useful:
    
    
    @Mock(lenient=true)
    

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59. @jeanneboyarsky
    JUnit Pioneer
    59
    Dependenc
    y
    
    testImplementation 'org.junit-pioneer:junit-pioneer:1.4.2
    '
    
    • Retry on failure (no param
    version)
    
    
    • Threadsafe scheduler for
    System.in/out
    
    
    • And so much more
    

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60. @jeanneboyarsky
    JUnit Pioneer
    60
    Dependenc
    y
    
    testImplementation 'org.junit-pioneer:junit-pioneer:1.4.2
    '
    
    • Retry on failure (no param
    version)
    
    
    • Threadsafe scheduler for
    System.in/out
    
    
    • And so much more
    

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61. @jeanneboyarsky
    Converting from JUnit 4
    61
    • IntelliJ does this well
    
    
    • Before that, I wrote a program
    which was adopted:
    
    
    https://github.com/junit-pioneer/
    convert-junit4-to-junit5
    

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62. @jeanneboyarsky
    Agenda
    ✅ Intro to JUnit 5
    
    
    ✅ Common testing patterns
    
    
    ✅ Brief look back at history
    
    
    (JUnit 3 and 4)
    
    
    ✅ JUnit 5 extensions
    
    
    ⭐ Interactive TDD live coding
    62
    

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63. @jeanneboyarsky
    Live TDD
    63
    • Let’s write some code!
    
    
    • Then book giveaway
    

    View Slide