Shulou(Shulou.com)06/03 Report--

Today, I will talk to you about the common ways of unit testing in JAVA, which may not be well understood by many people. in order to make you understand better, the editor has summarized the following content for you. I hope you can get something according to this article.

What is unit testing?

Unit testing (English: Unit Testing), also known as module testing, is a testing work that checks the correctness of program modules (the smallest unit of software design). A program unit is the smallest testable part of an application. In procedural programming, a unit is a single program, function, process, etc.; for object-oriented programming, the smallest unit is a method, including methods in a base class (superclass), an abstract class, or a derived class (subclass).

Generally speaking, programmers will conduct at least one unit test every time they modify the program, and there are likely to be multiple unit tests before and after writing the program to confirm that the program achieves the goals required by the software specification and that there are no program errors; although unit testing is not necessary, it is not bad, which involves project management policy decisions.

Advantages of unit testing

High-quality unit testing can ensure the quality of development and the robustness of programs. In most Internet enterprises, development engineers frequently execute test cases in the process of research and development. running failed single tests can help us quickly troubleshoot and locate problems so that they can be repaired before they are brought online. Just like a golden rule in the field of software engineering-the earlier a defect is discovered, the lower the cost of repairing it. The first-class test can find the fault that did not occur; the second-rate test can quickly locate the point where the fault occurred; the third-rate test is exhausted, always following the fault for functional regression. Unit testing tools commonly used in JAVA

JUnit/JUnit5

Https://junit.org/junit5/

Junit is an established testing framework and is by far the most widely used framework. It has been updated to Junit5, which is more powerful.

Class StandardTests {@ BeforeAll static void initAll () {} @ BeforeEach void init () {} @ Test void succeedingTest () {} @ Test void failingTest () {fail ("a failing test");} @ Test @ Disabled ("for demonstration purposes") void skippedTest () {/ / not executed} @ Test void abortedTest () {assumeTrue ("abc" .minutes ("Z")); fail ("test should have been aborted") @ AfterEach void tearDown () {} @ AfterAll static void tearDownAll () {}}

Assertj

Https://assertj.github.io/doc/

A powerful assertion tool that supports various assertions

/ / entry point for all assertThat methods and utility methods (e.g. Entry) import static org.assertj.core.api.Assertions.*;// basic assertionsassertThat (frodo.getName ()) .isEqualTo ("Frodo"); assertThat (frodo) .isNotEqualTo (sauron); / / chaining string specific assertionsassertThat (frodo.getName ()) .startsWith ("Fro") .endsWith ("do") .isEqualToIgnoringCase ("frodo") / / collection specific assertions (there are plenty more) / / in the examples below fellowshipOfTheRing is a ListassertThat (fellowshipOfTheRing) .hasSize (9) .is used to describe the test and will be shown before the error messageassertThat (frodo, sam) .doesNotContain (sauron); / / as () is used to describe the test and will be shown before the error messageassertThat (frodo.getAge ()) .as ("check% swatches age", frodo.getName ()) .isEqualTo (33); / / Java 8 exception assertion, standard style. AssertThatThrownBy (()-> {EqualTo ("boom!") ). HasMessage ("boom!"); / /. Or BDD styleThrowable thrown = catchThrowable (()-> {throw new Exception ("boom!");}); assertThat (thrown) .hasMessageContaining ("boom"); / / using the 'extracting' feature to check fellowshipOfTheRing character's names (Java 7) assertThat (fellowshipOfTheRing) .extracting ("name") .extraction ("Boromir", "Gandalf", "Frodo", "Legolas") / / same thing using a Java 8 method referenceassertThat (fellowshipOfTheRing) .extracting (TolkienCharacter::getName) .doesNotContain ("Sauron", "Elrond") / extracting multiple values at once grouped in tuples (Java 7) assertThat (fellowshipOfTheRing) .extracting ("name", "age", "race.name") .extraction (tuple ("Boromir", 37, "Man"), tuple ("Sam", 38, "Hobbit"), tuple ("Legolas", 1000, "Elf"); / / filtering a collection before asserting in Java 7. AssertThat (fellowshipOfTheRing) .filtered on ("race", HOBBIT) .containsOnly (sam, frodo, pippin, merry); / /. Or in Java 8assertThat (fellowshipOfTheRing) .filteredOn (character-> character.getName (). Contains ("o")) .containsOnly (aragorn, frodo, legolas, boromir); / / combining filtering and extraction (yes we can) assertThat (fellowshipOfTheRing) .filteredOn (character-> character.getName (). Contains ("o")) .containsOnly (aragorn, frodo, legolas, boromir) .extraction (character-> character.getRace (). GetName ()) .containsOnly ("Hobbit", "Elf", "Man") / / and many more assertions: iterable, stream, array, map, dates (java 7 and 8), path, file, numbers, predicate, optional.

Mockito

Https://site.mockito.org/

A unit test in the Mock tool, can be very flexible to create objects, with unit testing.

/ / You can mock concrete classes and interfacesTrainSeats seats = mock (TrainSeats.class); / / stubbing appears before the actual executionwhen (seats.book (Seat.near (WINDOW) .in (FIRST_CLASS)) .thenReturn (BOOKED); / / the following prints "BOOKED" System.out.println (seats.book (Seat.near (WINDOW) .in (FIRST_CLASS) / / the following prints "null" because / / .book (Seat.near (AISLE) .in (FIRST_CLASS)) was not stubbedSystem.out.println (seats.book (Seat.near (AISLE) .in (FIRST_CLASS)); / / the following verification passes because / / .book (Seat.near (WINDOW) .in (FIRST_CLASS)) has been invokedverify (seats) .book (Seat.near (WINDOW) .in (FIRST_CLASS)) / / the following verification fails because / / .book (Seat.in (SECOND_CLASS)) has not been invokedverify (seats) .book (Seat.in (SECOND_CLASS))

Other

For business code, unit testing is sometimes inconvenient because the cost of each startup is too high. You can use appropriate unit testing methods, such as providing a test interface that uses IDE's hot deployment feature to modify code without restarting.

However, for non-business code, unit testing is very necessary, we can find the problems in the code earlier, and at the same time, we can also verify the decoupling of the program.

Good code design will be more convenient in unit testing, whereas tightly coupled design will bring great trouble to unit testing.

After reading the above, do you have any further understanding of the common ways of unit testing in JAVA? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.