☝ It's failing because tests are not solved yet! 😊

According to www.codekatas.org

Code Kata is a term coined by Dave Thomas, co-author of the book The Pragmatic Programmer, in a bow to the Japanese concept of kata in the martial arts. A code kata is an exercise in programming which helps a programmer hone their skills through practice and repetition.

Also refer codekata.com

The Java8 Code Kata is created to walk-through java8 new API functions. I hope this helps you learn Java8 and get used to it. Repeating exercises will definitely upgrade your skills.

• Run the tests

You can run tests from your IDE or command line if you like. If you are using an IDE, right click on the test method and click Run foobar(). If you prefer command line, follow below.

$ pwd
/path/to/java8-code-kata

$ ./mvnw install -Dmaven.test.skip=true

$ ./mvnw test -Dtest=Exercise1Test#findRichCustomers -pl stream-api

• Edit unit tests.

To successfully pass the tests, you'll need to edit the test itself. You can see where you need to edit.

@Easy @Test
public void simpleAddition() {
    /**
     * Get an addition result of 1 and 2 by using an operator "+".
     */
    Integer added = null;

    assertThat(added, is(3));
}

Here is a sample answer.

@Easy @Test
public void simpleAddition() {
    /**
     * Get an addition result of 1 and 2 by using an operator "+".
     */
    Integer added = 1 + 2;

    assertThat(added, is(3));
}

Most tests are annotated with @Easy which means those tests only requires basic knowledge.

Tests annotated with @Difficult are more difficult. 😁

Check the 'solution' branch, but please try to solve by yourself at first.

• Exercise1Test.java

Iterable#forEach, Collection#removeIf, List#replaceAll, List#sort, Collection#stream and Collection#parallelStream

• Exercise2Test.java

Map#getOrDefault, Map#putIfAbsent, Map#merge and Map#computeIfPresent

• Exercise1Test.java

Stream#filter and Stream#map

• Exercise2Test.java

Stream#sorted, Stream#distinct, Stream#limit and Stream#flatMap

• Exercise3Test.java

Stream#count, Stream#max and Stream#min

• Exercise4Test.java

Stream#findFirst, Stream#allMatch, Stream#anyMatch and Stream#noneMatch

• Exercise5Test.java

Stream#collect and Collectors

• Exercise6Test.java

Stream#of and Stream#iterate

• Exercise7Test.java

IntStream, LongStream and DoubleStream

• Exercise8Test.java

Advanced problems

• Exercise9Test.java

Collector

• Exercise1Test.java

LocalDate#of, LocalDate#parse, LocalDate#with, LocalDate#plus, LocalDate#minus, LocalDate#isAfter, LocalDate#isBefore and LocalDate#until

• Exercise2Test.java

LocalTime#of, LocalTime#parse, LocalTime#with, LocalTime#plus, LocalTime#minus, LocalTime#isAfter, LocalTime#isBefore and LocalTime#truncatedTo

• Exercise3Test.java

LocalDateTime#of, LocalDateTime#parse, LocalDateTime#format, LocalDateTime#toLocalDate, LocalDateTime#toLocalTime, LocalDate#atTime and LocalTime#atDate

• Exercise4Test.java

ZonedDateTime#of, ZonedDateTime#parse, ZonedDateTime#format, LocalDateTime#atZone, ZonedDateTime#withZoneSameInstant and ZonedDateTime#withZoneSameLocal

• Exercise5Test.java

LocalDateTime to java.sql.Timestamp, LocalDate to java.sql.Date, and vice versa