DEV Community: Rafiullah Hamedy

JUnit 4 & 5 Annotations Every Developer Should Know

Rafiullah Hamedy — Tue, 05 Nov 2019 14:51:29 +0000

A Summary of JUnit 4 & 5 Annotations with Examples

Before writing this article, I only knew a few commonly used JUnit 4 annotations such as

@RunWith 
@Test
@Before
@After
@BeforeClass
@AfterClass

How many times did you have to comment out a test? To my surprise, there are annotations to do just that.

@Ignore("Reason for ignoring")
@Disabled("Reason for disabling")

Well, it turns out that there are a handful of other annotations, especially in JUnit 5 that could help write better and more efficient tests.

What to expect?

In this article, I will cover the following annotations with usage examples. The purpose of this article is to introduce you to the annotation, it will not go into greater details of each annotation.

*All the examples from this article are also available in the Github. Please checkout the following repository. *

rhamedy / junit-annotations-examples

JUnit 4 and 5 Annotations with Examples

The target audience of this article is developers of any level.

JUnit 4

The following JUnit 4 annotations will be covered

JUnit 5

The following JUnit 5 annotations are explained with examples

JUnit Dependencies

All the examples in this article are tested using the following JUnit dependencies.

testImplementation 'org.junit.jupiter:junit-jupiter-api:5.3.1'
testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.3.1'
testCompileOnly 'junit:junit:4.12'
testRuntimeOnly 'org.junit.vintage:junit-vintage-engine:5.3.1'

Please check out the Github repository for more details.

JUnit Annotations Usage

Let's explore the JUnit 4 annotations one by one with a brief usage example

The Hello World of Unit Testing

The @Test annotation is used to mark a method as a test.

public class BasicJUnit4Tests {
  @Test
  public void always_passing_test() {
    assertTrue("Always true", true);
  }
}

The Class-Level and Test-Level Annotations

Annotations such as @BeforeClass and @AfterClass are JUnit 4 class-level annotations.

public class BasicJUnit4Tests {
  @BeforeClass
  public static void setup() {
    // Setup resource needed by all tests.
  }
  @Before
  public void beforeEveryTest() {
    // This gets executed before each test.
  }
  @Test
  public void always_passing_test() {
    assertTrue("Always true", true);
  }
  @After
  public void afterEveryTest() {
    // This gets executed after every test.
  }
  @AfterClass
  public static void cleanup() {
    // Clean up resource after all are executed.
  }
}

The annotations @BeforeAll and @AfterAll are JUnit 5 equivalents and imported using the following statements.

// JUnit 5
import org.junit.jupiter.api.BeforeAll
import org.junit.jupiter.api.AfterAll

Ignoring a Test vs. Assumption

A test is ignored with @Ignore annotation or an assertion can be changed to an assumption and JUnit Runner will ignore a failing assumption.

Assumptions are used when dealing with scenarios such as server vs. local timezone. When an assumption fails, an AssumptionViolationException is thrown, and JUnit runner will ignore it.

public class BasicJUnit4Tests {
  @Ignore("Ignored because of a good reason")
  @Test
  public void test_something() {
    assertTrue("Always fails", false);
  }
}

Executing Tests in Order

Generally, it is a good practice to write order agnostic unit tests.

@FixMethodOrder(MethodSorters.NAME_ASCENDING)
public class FixedMethodOrderingTests {
  @Test
  public void first() {}
  @Test
  public void second() {}
  @Test
  public void third() {}
}

In addition to sorting in ascending order of test names, the MethodSorter allow DEFAULT and JVM level sorting.

Adding Timeout to Tests

Unit tests would mostly have fast execution time; however, there might be cases when a unit test would take a longer time.

In JUnit 4, the @Test annotation accepts timeout argument as shown below

import org.junit.Ignore;
import org.junit.Test;
public class BasicJUnit4Tests {
  @Test(timeout = 1)
  public void timeout_test() throws InterruptedException {
    Thread.sleep(2); // Fails because it took longer than 1 second.
  }
}

In JUnit 5, the timeout happens at the assertion level

import static java.time.Duration.ofMillis;
import static org.junit.jupiter.api.Assertions.assertTimeout;
import org.junit.jupiter.api.Test;
public class BasicJUnit5Tests {
  @Test
  public void test_timeout() {
    // Test takes 2 ms, assertion timeout in 1 ms
    assertTimeout(ofMillis(1), () -> {
      Thread.sleep(2);
    });
  }
}

Sometimes it is more meaningful to apply a timeout across all tests which includes the @BeforeEach/Before and @AfterEach/After as well.

public class JUnitGlobalTimeoutRuleTests {
  @Rule
  public Timeout globalTimeout = new Timeout(2, TimeUnit.SECONDS);
  @Test
  public void timeout_test() throws InterruptedException {
    while(true); // Infinite loop
  }
  @Test
  public void timeout_test_pass() throws InterruptedException {
    Thread.sleep(1);
  }
}

Using Rule with JUnit Tests

I find @Rule very helpful when writing unit tests. A Rule is applied to the following

Timeout - showcased above
ExpectedException
TemporaryFolder
ErrorCollector
Verifier

ExpectedException Rule

This rule can be used to ensure that a test throws an expected exception. In JUnit 4, we can do something as follow

public class BasicJUnit4Tests {
  @Test(expected = NullPointerException.class)
  public void exception_test() {
    throw new IllegalArgumentException(); // Fail. Not NPE.
  }
}

In JUnit 5, however, the above can be achieved via an assertion as follow

public class BasicJUnit5Tests {
  @Test
  public void test_expected_exception() {
    Assertions.assertThrows(NumberFormatException.class, () -> {
      Integer.parseInt("One"); // Throws NumberFormatException
    });
  }
}

We can also define a Rule in the class-level and reuse it in the tests

public class JUnitRuleTests {
  @Rule
  public ExpectedException thrown = ExpectedException.none();
  @Test
  public void expectedException_inMethodLevel() {
    thrown.expect(IllegalArgumentException.class);
    thrown.expectMessage("Cause of the error");
    throw new IllegalArgumentException("Cause of the error");
  }
}

TemporaryFolder Rule

This Rule facilities the creation and deletion of a file and folder during the lifecycle of a test.

public class TemporaryFolderRuleTests {
  @Rule
  public TemporaryFolder temporaryFolder = new TemporaryFolder();
  @Test
  public void testCreatingTemporaryFileFolder() throws IOException {
    File file = temporaryFolder.newFile("testFile.txt");
    File folder = temporaryFolder.newFolder("testFolder");
    String filePath = file.getAbsolutePath();
    String folderPath = folder.getAbsolutePath();

    File testFile = new File(filePath);
    File testFolder = new File(folderPath);
    assertTrue(testFile.exists());
    assertTrue(testFolder.exists());
    assertTrue(testFolder.isDirectory());
 }
}

ErrorCollector Rule

During the execution of a unit test, if there are many assertions and the first one fails then subsequent declarations are skipped as shown below.

@Test
public void reportFirstFailedAssertion() {
  assertTrue(false); // Failed assertion. Report. Stop execution.
  assertFalse(true); // It's never executed.
}

It would be helpful if we could get a list of all failed assertions and fix them at once instead of one by one. Here is how the ErrorCollector Rule can help achieve that.

public class ErrorCollectorRuleTests {
  @Rule
  public ErrorCollector errorCollector = new ErrorCollector();

  @Test
  public void reportAllFailedAssertions() {
    errorCollector.checkThat(true, is(false));  // Fail. Continue
    errorCollector.checkThat(false, is(false)); // Pass. Continue
    errorCollector.checkThat(2, equalTo("a"));  // Fail. Report all
  }
}

There is also the Verifier Rule that I won't go into details, and you can read more about it here.

For more information on @ClassRule and the difference between the two, please see this Stackoverflow post.

JUnit Suites

The JUnit Suites can be used to group test classes and execute them together. Here is an example

public class TestSuiteA {
  @Test
  public void testSuiteA() {}
}
public class TestSuiteB {
  @Test
  public void testSuiteB() {}
}

Assuming that there are many other test classes, we could run both or one of these using the following annotations

@RunWith(Suite.class)
@Suite.SuiteClasses({TestSuiteA.class, TestSuiteB.class})
public class TestSuite {
  // Will run tests from TestSuiteA and TestSuiteB classes
}

The above would result in the following

Categories in JUnit 4

In JUnit 4, we can make use of the Categories to include and exclude a group of tests from execution. We can create as many categories as we want using a marker interface as shown below

An interface with no implementation is called a marker interface.

public interface CategoryA {}
public interface CategoryB {}

Now that we have two categories, we can annotate each test with one or more category types as shown below

public class CategoriesTests {
  @Test
  public void test_categoryNone() {
    System.out.println("Test without any category");
    assert(false);
  }
  @Category(CategoryA.class)
  @Test
  public void test1() {
    System.out.println("Runs when category A is selected.");
    assert(true);
  }
  @Category(CategoryB.class)
  @Test
  public void test2() {
    System.out.println("Runs when category B is included.");
    assert(false);
  }
  @Category({CategoryA.class, CategoryB.class})
  @Test
  public void test3() {
    System.out.println("Runs when either of category is included.");
    assert(true);
  }
}

A special JUnit Runner called Categories.class is used to execute these tests

@RunWith(Categories.class)
@IncludeCategory(CategoryA.class)
@ExcludeCategory(CategoryB.class)
@SuiteClasses({CategoriesTests.class})
public class CategroyTestSuite {}

The above would only run test test1 , however, if we remove the following entry then both test1 and test3 are executed.

@ExcludeCategory(CategoryB.class)

Tagging & Filtering Tests in JUnit 5

In addition to the Categories in JUnit 4, JUnit 5 introduces the ability to tag and filter tests. Let's assume we have the following

@Tag("development")
public class UnitTests {
  @Tag("web-layer")
  public void login_controller_test() {}
  @Tag("web-layer")
  public void logout_controller_test() {}
  @Tag("db-layer")
  @Tag("dao")
  public void user_dao_tests() {}
}

and

@Tag("qa")
public class LoadTests {
  @Tag("auth")
  @Test
  public void login_test() {}
  @Tag("auth")
  @Test
  public void logout_test() {}
  @Tag("auth")
  @Test
  public void forgot_password_test() {}
  @Tag("report")
  @Test
  public void generate_monthly_report() {}
}

As shown above, tags apply to both the entire class as well as individual methods. Let's execute all the tests tagged as qa in a given package.

@RunWith(JUnitPlatform.class)
@SelectPackages("junit.exmaples.v2.tags")
@IncludeTags("qa")
public class JUnit5TagTests {}

The above would result in the following output

As shown above, only the test class with qa tag is run. Let's run both qa and development tagged tests but, filter the dao and report tagged tests.

@RunWith(JUnitPlatform.class)
@SelectPackages("junit.exmaples.v2.tags")
@IncludeTags({"qa", "development"})
@ExcludeTags({"report", "dao"})
public class JUnit5TagTests {}

As shown below, the two tests annotated with dao and report are excluded.

Parametrizing Unit Tests

JUnit allows parametrizing a test to be executed with different arguments instead of copy/pasting the test multiple times with different arguments or building custom utility methods.

@RunWith(Parameterized.class)
public class JUnit4ParametrizedAnnotationTests {
  @Parameter(value = 0)
  public int number;
  @Parameter(value = 1)
  public boolean expectedResult;
  // Must be static and return collection.
  @Parameters(name = "{0} is a Prime? {1}")
  public static Collection<Object[]> testData() {
    return Arrays.asList(new Object[][] {
      {1, false}, {2, true}, {7, true}, {12, false}
    });
  }
  @Test
  public void test_isPrime() {
    PrimeNumberUtil util = new PrimeNumberUtil();
    assertSame(util.isPrime(number), expectedResult);
  }
}

To parametrize the test_isPrime test we need the following

Make use of the specialized Parametrized.class JUnit Runner
Declare a non-private static method that returns a Collection annotated with @Parameters
Declare each parameter with @Parameter and value attribute
Make use of the @Parameter annotated fields in the test

Here is how the output of our parameterized test_isPrime look like

The above is a using @Parameter injection, and we can also achieve the same result using a constructor, as shown below.

public class JUnit4ConstructorParametrized {
  private int number;
  private boolean expectedResult;

  public JUnit4ConstructorParametrized(int input, boolean result) {
    this.number = input;
    this.expectedResult = result;
  }
  ...
}

In JUnit 5, the @ParameterizedTest is introduced with the following sources

The @ValueSource
The @EnumSource
The @MethodSource
The @CsvSource and @CsvFileSource

Let's explore each of them in detail.

Parameterized Tests with a ValueSource

The @ValueSource annotation allows the following declarations

@ValueSource(strings = {"Hi", "How", "Are", "You?"})
@ValueSource(ints = {10, 20, 30})
@ValueSource(longs = {1L, 2L, 3L})
@ValueSource(doubles = {1.1, 1.2, 1.3})

Let's use one of the above in a test

@ParameterizedTest
@ValueSource(strings = {"Hi", "How", "Are", "You?"})
public void testStrings(String arg) {
  assertTrue(arg.length() <= 4);
}

Parameterized Tests with an EnumSource

The @EnumSource annotation could be used in the following ways

@EnumSource(Level.class)
@EnumSource(value = Level.class, names = { "MEDIUM", "HIGH"})
@EnumSource(value = Level.class, mode = Mode.INCLUDE, names = { "MEDIUM", "HIGH"})

Similar to ValueSource, we can use EnumSource in the following way

@ParameterizedTest
@EnumSource(value = Level.class, mode = Mode.EXCLUDE, names = { "MEDIUM", "HIGH"})
public void testEnums_exclude_Specific(Level level) {
  assertTrue(EnumSet.of(Level.MEDIUM, Level.HIGH).contains(level));
}

Parameterized Tests with a MethodSource

The @MethodSource annotation accepts a method name that is providing the input data. The method that provides input data could return a single parameter, or we could make use of Arguments as shown below

public class JUnit5MethodArgumentParametrizedTests {
  @ParameterizedTest
  @MethodSource("someIntegers")
  public void test_MethodSource(Integer s) {
    assertTrue(s <= 3);
  }

  static Collection<Integer> someIntegers() {
    return Arrays.asList(1,2,3);
  }
}

The following is an example of Arguments and it can also be used to return a POJO

public class JUnit5MethodArgumentParametrizedTests {
  @ParameterizedTest
  @MethodSource("argumentsSource")
  public void test_MethodSource_withMoreArgs(String month, Integer number) {
    switch(number) {
      case 1: assertEquals("Jan", month); break;
      case 2: assertEquals("Feb", month); break;
      case 3: assertEquals("Mar", month); break;
      default: assertFalse(true);
    }
  }
static Collection<Arguments> argumentsSource() {
    return Arrays.asList(
      Arguments.of("Jan", 1),
      Arguments.of("Feb", 2),
      Arguments.of("Mar", 3),
      Arguments.of("Apr", 4)); // Fail.
  }
}

Parameterized Tests with a CSV Sources

When it comes to executing a test with a CSV content, the JUnit 5 provides two different types of sources for the ParametrizedTest

A CsvSource - comma-separated values
A CsvFileSource - reference to a CSV file

Here is an example of a CsvSource

@ParameterizedTest
@CsvSource(delimiter=',', value= {"1,'A'","2,'B'"})
public void test_CSVSource_commaDelimited(int i, String s) {
  assertTrue(i < 3);
  assertTrue(Arrays.asList("A", "B").contains(s));
}

Assuming that we have the following entries in sample.csv file under src/test/resources

Name, Age
Josh, 22
James, 19
Jonas, 55

The CsvFileSource case would look as follow

@ParameterizedTest
@CsvFileSource(resources = "/sample.csv", numLinesToSkip = 1, delimiter = ',', encoding = "UTF-8")
public void test_CSVFileSource(String name, Integer age) {
  assertTrue(Arrays.asList("James", "Josh").contains(name));
  assertTrue(age < 50);
}

Resulting in 2 successful test runs and one failure because of the last entry in sample.csv that fails the assertion.

You can also design custom converters that would transform a CSV into an object. See here for more details.

Theory in JUnit4

The annotation @Theory and the Runner Theories are experimental features. In comparison with Parametrized Tests, a Theory feeds all combinations of the data points to a test, as shown below.

@RunWith(Theories.class)
public class JUnit4TheoriesTests {
  @DataPoint
  public static String java = "Java";
  @DataPoint
  public static String node = "node";
  @Theory
  public void test_theory(String a) {
    System.out.println(a);
  }
  @Theory
  public void test_theory_combos(String a, String b) {
    System.out.println(a + " - " + b);
  }
}

When the above test class is executed, the test_theory test will output 2¹ combination

Java
node

However, the test test_theory_combos would output all the combinations of the two data points. In other words, 2² combinations.

Java - Java
Java - node
node - Java
node - node

If we have the following data point oss then test_theory_one test would generate 2³ combinations (2 number of args ^ 3 data points). The test test_theory_two would create 3³ combinations.

@DataPoints
public static String[] oss = new String[] {"Linux", "macOS", "Windows"};
@Theory
public void test_theory_one(String a, String b) {
  System.out.println(a + " - " + b);
}
@Theory
public void test_theory_two(String a, String b, String c) {
  System.out.println(a + " <-> " + b + "<->" + c);
}

The following is a valid data point

@DataPoints
public static Integer[] numbers() {
  return new Integer[] {1, 2, 3};
}

JUnit 5 Test DisplayName

JUnit 5 has introduced @DisplayName annotation that is used to give an individual test or test class a display name, as shown below.

@Test
@DisplayName("Test If Given Number is Prime")
public void is_prime_number_test() {}

and it would show as follow in the console

Repeating a JUnit Test

Should the need arise to repeat a unit test X number of times, JUnit 5 provides @RepeatedTest annotation.

@RepeatedTest(2)
public void test_executed_twice() {
  System.out.println("RepeatedTest"); // Prints twice
}

The @RepeatedTest comes along with currentReptition, totalRepetition variables as well as TestInfo.java and RepetitionInfo.java Objects.

@RepeatedTest(value = 3, name = "{displayName} executed {currentRepetition} of {totalRepetitions}")
@DisplayName("Repeated 3 Times Test")
public void repeated_three_times(TestInfo info) {
  assertTrue("display name matches", 
     info.getDisplayName().contains("Repeated 3 Times Test"));
}

We could also use the RepetitionInfo.java to find out the current and total number of repetitions.

Executing Inner Class Unit Tests using JUnit 5's Nested

I was surprised to learn that JUnit Runner does not scan inner classes for tests.

public class JUnit5NestedAnnotationTests {
  @Test
  public void test_outer_class() {
    assertTrue(true);
  }
  class JUnit5NestedAnnotationTestsNested {
    @Test
    public void test_inner_class() {
      assertFalse(true); // Never executed.
    }
  }
}

When Running the above test class, it will only execute the test_outer_class and report success, however, when marking the inner class with @Nested annotation, both tests are run.

JUnit 5 Test Lifecycle with TestInstance Annotation

Before invoking each @Test method, JUnit Runner creates a new instance of the class. This behavior can be changed with the help of @TestInstance

@TestInstance(LifeCycle.PER_CLASS)
@TestInstance(LifeCycle.PER_METHOD)

For more information on @TestInstance(LifeCycle.PER_CLASS) please check out the documentation.

DynamicTests using JUnit 5 TestFactory Annotation

JUnit tests annotated with @Test are static tests because they are specified in compile-time. On the other hand, DynamicTests are generated during runtime. Here is an example of DynamicTests using the PrimeNumberUtil class.

public class Junit5DynamicTests {
  @TestFactory
  Stream<DynamicTest> dynamicTests() {
    PrimeNumberUtil util = new PrimeNumberUtil();
    return IntStream.of(3, 7 , 11, 13, 15, 17)
       .mapToObj(num -> DynamicTest.dynamicTest("Is " + num + " Prime?", () -> assertTrue(util.isPrime(number))));
    }
}

For more on dynamic tests, see this blog post.

Conditionally Executing JUnit 5 Tests

JUnit 5 introduced the following annotations to allows conditional execution of tests.

@EnabledOnOs, @DisabledOnOs, @EnabledOnJre, @DisabledOnJre, @EnabledForJreRange, @DisabledForJreRange, @EnabledIfSystemProperty, @EnabledIfEnvironmentVariable, @DisabledIfEnvironmentVariable, @EnableIf, @DisableIf

Here is an example of using @EnabledOnOs and @DisabledOnOs

public class JUnit5ConditionalTests {
  @Test
  @DisabledOnOs({OS.WINDOWS, OS.OTHER})
  public void test_disabled_on_windows() {
    assertTrue(true);
  }
  @Test
  @EnabledOnOs({OS.MAC, OS.LINUX})
  public void test_enabled_on_unix() {
    assertTrue(true);
  }
  @Test
  @DisabledOnOs(OS.MAC)
  public void test_disabled_on_mac() {
    assertFalse(false);
  }
}

I am using a MacBook, and the output looks as follow

For examples of other annotations, please check out these tests.

Conclusion

Thank you for reading along. Please share your thoughts, suggestions, and feedback in the comments.

Please Feel free to follow me on dev.to for more articles, Twitter, and join my professional network on LinkedIn.

Lastly, I have also authored the following articles that you might find helpful.

A guide on how to get started with contributing to open source

Why you should think twice about contributing to Open Source

Rafiullah Hamedy ・ Aug 22 '19 ・ 7 min read

#opensource #beginners #productivity #motivation

A listing of key habits that in my opinion would help you become a better developer

Key habits and things I wish I knew earlier as a developer

Rafiullah Hamedy ・ Aug 6 '19 ・ 9 min read

#beginners #career #java #javascript

Finally, a short summary of coding best practices for Java

A short summary of Java coding best practices | by Rafiullah Hamedy | Medium

Rafiullah Hamedy ・ Aug 18, 2020 ・ 14 min read
Medium

Contribution Debt: Why & How to Contribute to Stack Overflow

Rafiullah Hamedy — Thu, 03 Oct 2019 01:20:24 +0000

Why & How to Stop Procrastinating and Start Contributing

Stack Overflow is world’s leading Q&A sites for developers with over 18+ million questions, 28+ million answers and 11+ million users.

A huge majority of developers use Stack Overflow on daily basis and I would like to share my thoughts on

Why do I contribute?
How to contribute?
What are the benefits of contributing?

I joined the Stack Overflow community in 2012 and my contributions in the form of answering questions peaked between Nov 2015 — Feb 2016 which attributes to a huge chunk of my reputation score.

I have posted 168 answers and asked 22 questions with a people reach of roughly ~648K
I have ~5.2K reputation in Stack Overflow, 792 in Drupal Answers and below 200 in other communities
I have 27 helpful post edits, flags and casted a total of 585 upvote and downvotes

I am no rockstar contributor but, do I feel good about it? Ofcourse! I feel great to have been able to contribute back regardless of the quantity.

Why do I contribute?

Stack Overflow without any doubt has helped me countless times throughout my software development career.

Search for answers to specific questions
Clear my confusion about topics
Quickly learn about a topic instead of going through articles and books when I don’t have enough time
Come back to my favourite questions and answers

All of the above become possible because somebody, somewhere selflessly decided to share their knowledge.

I benefit from other’s contributions and this is good enough reason for me to contribute back and hope that my contributions help others.

I have come across developers who use Stack Overflow on daily basis and some of them have not even bothered to signup. Somebody asked about this in Stack Overflow.

While the accepted answer is not wrong, I still believe that you should sign up regardless of the reasons highlighted in the answer.

Remember! Signing up is the first step towards contributing back.

How to contribute?

Any kind of contribution that leave the community in a better state than you found it is a good form of contribution. For instance, any of the following is a valid form of contribution

You can improve the quality of a post
Ask good questions that has not already been asked
Answer question about a topic that you are knowledgeable
Upvote questions and answers that helped you
Downvote but, do not forget to share your reasons
Leave helpful comments
Vote in the community election
Motivate others to contribute back

Ask questions

The Stack Overflow community has come under the spotlight for not being welcoming to new users and questions however, there are many ways that you could ask a meaningful and welcoming question.

Make sure to read the necessary guidelines before posting a question. Read it here
Ensure that the question has not already been asked. If there are any related questions and does not necessarily solve your use case, then state that in your question.
When posting a question, be sure to share what you have done so far. This shows that you have put some efforts and done your research.
Make sure to format your question and use the appropriates tags
Do not copy/paste class assignments and projects
Do not cross-post your question to different communities and platforms

If you make a post, keep an eye on flags and comments and update your post to address the concerns of those who flag your posts.

Answer questions

Do not underestimate your ability to answer questions and there are many ways to do that.

I am not an expert in any of the above domains but, I know enough and have used it either at work or in side projects.

Configure your profile by subscribing to tags (i.e. java, typescript, react, etc.) and Stack Overflow will filter questions that match your tags.
Do not post an answer if your response can be a comment instead.
Before writing an answer clarify any confusions via comments.
Keep your environment ready to try something hands-on in order to validate your solution.
If you quote or copy/paste content from a tutorial, documentation, or another posts then make sure to link the source and give credit where due.
If you wish to gain more reputation tackle questions with bounties. These questions would require a little more effort.
If none of the answers to a question resolved your issue then, be sure to post the solution that fixed your case.

Answer your own questions

There will come a time when you won’t find an answer to your question in Stack Overflow. What do you do next?

Use your ninja search skills to look for answers to your question.
Consider posting a question in the Stack Overflow and hope that you get an helpful answer soon.
While your question is awaiting to be answered, do your research to find out an answer by reading the documentation, articles, books, and other materials.
If and when you find the answer then go back to your asked question and answer it yourself.

As weird as this sounds, IMO it is basically sharing your knowledge so that the next person who have stumbles upon a similar question could benefit from your findings. This is a list of questions that I asked and answered them myself and people have found it to be helpful.

Jul 4 '18 Comments: 1 Answers: 7

I have a use case where I pull and plot Forex data in the form of ask and bid on the graph and this is based on minute, hour or day candlesticks and I am only plotting the closing value for bid and ask as a spline.

Issue

The…

Open Full Question

I was playing around with financial charts and wanted to remove the weekend datetime from the graph.

Mar 5 '17 Comments: 1 Answers: 1

I started to use Spring OAuth2 and in the process, I struggled to find relevant tutorials and content mostly because of the following

I did not want to use Spring Boot
I did not want to use Java configs rather xml configuration
I needed to customize Spring OAuth2 grant flows…

Open Full Question

Likewise, I struggled to find answer to my non-Spring Boot related questions and when I did find the answers then I shared it.

Feb 6 '18 Comments: 1 Answers: 1

I like Swagger because it makes your apis very user friendly. I use Swagger annotations like

@ApiParam
@ApiResponse | @ApiResponses
@ApiOperation
Others

On endpoints, query params, request params, request body and so on.

I like to keep my POJO classes clean and in general I try my best to follow…

Open Full Question

I was using Swagger for my APIs and at one point I noticed that each endpoint has around seven (7) swagger annotations. I thought to myself, can I make these annotations reusable?

The following question was asked way back in 2014 and since a lot has changed and different versions of the framework has been released. None of the answers worked for my use case and I posted my own version of answer and not surprisingly 21 people have found it to be helpful.

Oct 21 '14 Comments: 6 Answers: 18

123

I'm trying to set up HikariCP in my Spring Boot (1.2.0.M1) app so I can test using it in place of Tomcat DBCP. I'd like to configure the connection pool in my application.properties file like I was doing with Tomcat, but I can't figure out how I should be doing…

Open Full Question

Upvoting and downvoting posts

There are many advantages when it comes to upvoting posts such as

Your vote help rank the posts
Your upvote shows your appreciation
Your upvote encourages the author to make more helpful posts

All you have to ask yourself is, did this question or answer help me? If yes, then upvote the question and answer. Simple as that.

When you downvote, be sure to provide a comment explaining your reasoning and keep an open mind. I have 3 downvotes and 566 upvotes.

What are the benefits of contributing?

In my opinion, it is the right thing to do and that’s is good enough reason.

Here are some of the benefits of contributing to Stack Overflow vs not contributing

Give back to the community ❤
Communicate with other developers
Share your existing knowledge
Acquire new knowledge
Learn how to write effective posts
Use your Stack Overflow profile elsewhere to promote yourself
Setup your job preference in Stack Overflow to explore jobs and receive offers

Conclusion

Thank you for reading. Please feel free to share your ideas, suggestions, feedback and strategies on how to get started and succeed at contributing to Stack Overflow community.

If contributing to open source interest you then you might find the following article useful.

Why you should think twice about contributing to Open Source

Rafiullah Hamedy ・ Aug 22 '19

#opensource #beginners #productivity #motivation

I also wrote an article on some of the key habits that in my opinion would help you become a better developer.

Key habits and things I wish I knew earlier as a developer

Rafiullah Hamedy ・ Aug 6 '19

#beginners #career #java #javascript

Please follow me for future articles and feel free to add me to your professional network on LinkedIn.

Why you should think twice about contributing to Open Source

Rafiullah Hamedy — Thu, 22 Aug 2019 05:01:18 +0000

7 out of 10 developers contribute to open source and here are some tips and suggestions on how to get started

It’s no secret that Open Source contribution is one of the most sought after skills in tech. In addition to the employment benefits, there are other advantages such as

Learning and sharing knowledge
Build and improve your brand’s visibility
Collaboration and communication with other developers through code reviews and discussions
Giving back to the community ❤
Connect with like minded people, find your employee/employees, co-founder, mentor, mentee

According to Eclipse Foundation, Open Source has seen massive investment in recent years.

Why should you care?

Looking back to the 2016 StackOverflow survey, there is no mention of open source at all however, in 2017 survey around 32.7% of respondents claimed to contribute to open source and this figure increased by nearly 10% (to 43.6%) in 2018 survey and what is even more interesting is that the % of contributors rose by 20% in 2019 (to 63.3%).

According to a 2016 Future of Open Source Survey Results by BlackDuck around 67% of participation in open source has been to

Fix bugs
Add new features

59% of developers participate in open source to gain competitive edge.

Taking into account the above facts, figures and trends, IMO it’s worth considering open source contribution.

Be the change that you wish to see in the world — Mahatma Gandhi

Reasons why I failed to contribute earlier?

A majority of us developers love to contribute to open source but, we end up failing to do so for a variety of reasons. Here is a listing of reasons for me

A majority of educational institutions neither recognize open source contribution as an effective way to learn nor motivate the students to participate — IMO, open source contribution should be part of the curriculum (as assignment, project, etc).

Your geographical location — IMO the country you live in also plays a vital role as highlighted in this article.
New year resolution & birthday promises — I have had countless of these but, they never really worked.
Unrealistic goals — I once decided that I will do at least twenty (20) pull requests to repository such as docker (because I ❤ docker) without taking into account the fact that I did not have the adequate knowledge to do so.
Job, side projects and life excuses — Following every failure to contribute, I would consult myself that I am doing well in other verticals.

No matter how small the contribution, if you do it on a regular basis it does make a difference in the long run.

Underestimating my abilities — At times I have looked into existing pull requests and issues and arrived to the conclusion that “This is complex”.
Ignoring documentation issues — A majority times I have ignored all the documentation related issues.

My employers didn't care — I would love a job that requires contributing back to the open source community.
Procrastination — Definitely a factor for a variety of reasons.

These are some of the main reasons that stopped me from getting started with open source contribution early on.

My Motivation

The main motivation to contribute to open source for me was to become knowledgeable enough to write about it.

I have a strong emphasis on knowledge sharing and this is something that I try to do both personally as well as at work in team and organisation level.

I was working on a side project last year and I learned a few things about encryption, so I wrote about it here. Few months down the road, I helped write our company’s coding guidelines and used the knowledge to write an article about it as well.

After two articles, I wanted to write about something that I regarded as really important for new devs and students (Medium version, not metered).

Key habits and things I wish I knew earlier as a developer

Rafiullah Hamedy ・ Aug 6 '19

#beginners #career #java #javascript

The community loved ❤ the article and received around ~50K views, many thousand claps and comments of appreciation (In Medium - prior to their Paywall).

The next big article for me was to write about open source contribution (this article) and for that I needed to make a few open source contributions first.

So if you find yourself in the same boat of wanting to contribute and have not yet then, look for that one reason, motivation, purpose, drive, whatever it is.

My Contribution Strategy

I decided that I will contribute to a Spring Framework, a library that I have used before. I was reading the Contribution Guidelines when I noticed a few broken links so, I created a pull request to fix them.

The pull request got merged and it felt so good that I decided to keep going however, there was a problem. A majority of GitHub issues (i.e. bugs, first-timer, help-needed, feature) would get picked by other contributors before I even have a chance to express interest.

Whenever a process does not produce the desired result for me, I make a change and re-evaluate the results and continue this way until the results are desirable.

Here is what I did

I subscribed (watched) to the Spring repository
On my way to work, I would browse through email notifications and show interest via comment on issues that I could tackle

As a result of this strategy, I had a pool of issues to work on. The first enhancement feature

Add Clear Site Data to Log Out #4187

rwinch posted on Jan 06, 2017

We should investigate adding Clear Site Data to Spring Security's LogoutHandler implementations. See https://w3c.github.io/webappsec-clear-site-data/

View on GitHub

and the pull request for it

Add Support for Clear Site Data on Logout #6550

rhamedy posted on Feb 22, 2019

This PR adds support for Clear Site Data HTTP response header. See the issue for more details.

Fixes #4187

View on GitHub

I continued in this fashion on a few other issues of type enhancement, bugs and new features resulting in the following PRs

Add placeholder support for header tag attributes — Spring Security
Add configuration properties for remaining Undertow — Spring Boot
Ensure Qualifier with bean name is evaluated when using SpyBean — Spring Boot — Declined
Convert PluginPropertiesExtension Groovy to Java — ElasticSearch
Added Support for RFC 8414 OAuth 2.0 Authorization Server Metadata — Spring Security

So, if you are struggling to find issues to work on, pivot to a different strategy.

Tips and Suggestions

Based on my knowledge and experience so far

Participate in Hacktoberfest
A must-read guide on “how to contribute”
Learn Git basics
Pick a language i.e. Java, JavaScript
Identify repositories that welcome contributions — Use tools such as CodeTriage, Github Explorer and this
Read the repository policies i.e. contribution guidelines
Learn the project you want to contribute to
Contribute in the form of code, documentation, bugs, and new features
Filter issues based on labels such as help-needed, bug, first-timers, etc.
Be mindful of others time specially maintainers who help you
Ensure you have the necessary skills and time to invest
Follow the discussions in issues and pull requests, see the code changes
Be patient and open to feedback

I picked an Elastic Search issue and ignored the fact that I needed to know some Groovy and how Elastic Search build worked as a consequence I spent a lot more time and effort in getting the PR to completion stage.

It’s always a good idea to do some research before opting to work on an issue.

Key habits and things I wish I knew earlier as a developer

Rafiullah Hamedy — Tue, 06 Aug 2019 05:25:22 +0000

A listing of key habits and skills that could help you become a better developer

What are some of the things that you wish you knew earlier as a developer? Any habit, book, article or skill? Please share in the comment section.

Summary

Here is a quick summary of habits and things that in my opinion would make a huge difference if known earlier as a developer. Of course, It is never too late

Efficient use of search engines
Use modern IDE for increased productivity
Learn Linux
Learn Git
Coding standards matter
Teach yourself & follow tech trends
Listen to tech podcasts
Become proficient in at least one programming language
Focus on Simplicity
Learn Design Patterns
Join communities/forums
Create professional profiles
Ask, Ask, Ask
Solve it in paper first then convert into code
Document and write tests from start
Solve puzzles/challenges on regular basis
Start whiteboarding early on
Manage your time efficiently
Protect your personal information
Follow influencers & companies that inspire you
Attend tech events, workshops, talks, and hackathons
Embrace error messages ❤
Choose the right type of company for internship/career
First develop a working solution then perfect it iteratively
SEO yourself

As as usual watch out for the following habits/patterns

Do not give up so easy! ❤
Do not copy assignments/projects
Do not procrastinate — if not now, when?
Do not ignore other subjects
Do not get addicted to social networks
Do not lose hope

mpj 💛

@mpjme

New programmers are often uncertain if they will ever be good enough. As we grow more experienced, we learn to relax in the total certainty that we'll never be good enough.

17:44 PM - 12 Jun 2018

2036 5900

Learning

Learning is a prerequisite to thriving in tech due to the speed at which the industry is evolving. There is always something new to learn.

Once you stop learning, you start dying — Albert Einstein

Search efficiently

As a developer, you will use search engines very often and a majority of search engines offer advanced features. See tips and infographics

Development IDEs

IDEs such as IntelliJ, Atom come with shortcuts, plugins and features aimed to increase your productivity. Invest a little time to learn how to best use an IDE.

Learn Linux

Installing Ubuntu natively, using VirtualBox or Windows Subsystem for Linux is a piece of cake. Linux/Unix knowledge is a huge plus.

Learn Git

Git is one of the most popular code versioning tool. I suggest start Git-ing as early as possible with your projects and assignments. A great way to learn Git is through documentation, article and maybe this interactive online resource.

Teach Yourself

It is a fact that your program of study does not prepare you for real world regardless of university’s ranking, depth of the curriculum or caliber of the professors. Nowadays there is no shortage of learning materials both offline and online.

crunchzilla is a step by step how to code games for beginners. My favourite Youtube channels are Derek Banas, LearnCode Academy, FreeCodeCamp and CodingTech. Finally, a listing of open courseware on EDX, Stanford Online, and MIT OpenCourseWare that you could learn from.

Learn at least one language concretely

At university, I studied C Programming for 2 years from Basics to Advanced Data Structure. It helped build a strong programming foundation and every other language become a mere change of syntax, terminology and structure.

Focus on Simplicity

You will be surprised how in-demand simplicity is when it comes to coding and no one admires code that is complex, hard to understand and maintain.

Simplicity is a prerequisite for reliability. — Edsger W. Dijkstra

Coding Standards Matter

It is very common for code to migrate from one dev to another over it is lifespan. It's critical to follow a commonly adopted coding guidelines to ensure that the code is easy to understand, extend and maintain. Click the image below to read my article on Java Coding Best Practices.

Learn Design Patterns

Similar to coding standards, knowledge of design patterns help you architect close to immortal systems (ok maybe not immortal, but you get the point).

Listen to tech podcasts

Podcast are great ways to broaden your technical knowledge when commuting, walking, driving and so on. I would highly recommend checking out the Software Engineering Daily podcast.

Communities & Profiles

Communities are where you network with like minded professionals, learn and give back.

GitHub

Creating a profile allow you to setup your own repos, follow inspiring contributors, appreciate others work by staring their repository, and most importantly contribute back to the open source projects. Here is my GitHub profile.

How to contribute? You can report a bug, write documentation, answer questions, fix issues and create new features.

It’s worth-mentioning that, employers favour open source contributors.

StackOverflow

StackOverflow is the largest Software Development Q&A website. A SO profile is good to have. See Rob’s comment on its significance in interviews.

Ask difficult & meaningful questions
Answer questions
Upvote useful questions/answers

A LinkedIn profile is the first step towards building your online presence.

Build your professional network
Subscribe to updates from companies & influencers
Explore jobs, write and read posts

Similarly, AngelList and IndieHackers, Reddit are great communities to be a member of. See my profile below for my profiles.

.ltag__user__id__202225 .follow-action-button { background-color: #080E3B !important; color: #FFFFFF !important; border-color: #080E3B !important; }

Rafiullah Hamedy

After trying dev.to, I have decided to do a u-turn to medium for my future article.

rhamedy

Habits

Developing a few habits early on would greatly help you down the road. I highly recommend reading The Power of Habit by Charles Duhigg.

Tech is a fast-paced industry. Stay up to date with social networks & sites such as slashdot & techcrunch.
Don’t be shy! Ask for advice from those with expertise
Always plan and solve the problem in paper and then write the code. This is very powerful.
Write code that aligns with industry adopted coding standards. Start writing tests early for assignments, projects.
Develop a habit of solving puzzles/challenges on regular basis. This will serve you dearly whether it’s interview, your job, side project, etc.
Whiteboarding skill never let you down whether it is interview, on the job. Probably one of the most overlooked skill.
Understand how much time you have in your hand and use it wisely. Do the math, calendar block tomorrow and use RescueTime/Toggl if you are comfortable with their Privacy Policy.
Protect your identity by reading privacy policies, terms of services, using VPN & Encryption, password manager, enabling 2FA, and so on.

Socializing & Networking

There are many benefits to networking and socializing such as

Build your professional network
Get inspired and inspire others
Learn about the dev communities, jobs, mentoring, volunteering, etc
Find your co-founders and project partners
Improve your soft skills i.e. speaking, active listening, and so on.

We are well past the era of one man army, it is all about teamwork now. Get to know people of all expertise i.e. legal, finance, sales, marketing and so on. It will come handy in the future be it side projects, change industry, etc.

If you find networking difficult, I recommend reading self help books i.e. Quiet: The Power of Introverts in a World That Can’t Stop Talking and there is a ton of tips and advice on internet.

Follow Influencers & Companies

Put social networks into good use. Follow people and companies that inspire and remind you of your dreams and goals. I use social networks to

Stay connected with family and friends
Read updates from companies such Google, Microsoft, Apple, United Nations, Amazon, Netflix, SpaceX, Tesla, and so on.
Follow public figures like Elon Musk, Bill Gates, Leonardo DiCaprio, Jeff Atwood, Dan Abramov, Dave Syer, Evan You, Vitalik Buterin and so on.
Attend monthly meetups (i.e. Hackernest), workshops, talks, hackathons

Side Projects

Act on your ideas. The chances that someone else is thinking about it is very high.

Pick that great idea and do a feasibility and market research
Connect with your professional network to find partners & co-founders
Work in your free time while maintaining a healthy work/life balance & don’t forget to see the idea through completion

Researching

As a Software Developer you will be constantly learning and researching. Give yourself the habit of reading the documentation first and if that did not help then search for other learning materials such as examples, tutorials, etc.

Error Messages

Don’t be disappointed when you come across an error message. Learn What is it about? When does it happen? and How to handle it gracefully?

Choose the right Company

Recently, I came across this article by Brenn where he explains the benefits of working for a Product vs Consulting company — Might help decide your next career/internship option.

SEO Yourself

Have you ever googled yourself? Is your personal information safe? Is your public information easily accessible? Use the magic of search engine to achieve your objectives whether it’s sharing wisdom, promoting your brand, attracting followers, or spreading awareness.

Things you should avoid

It takes time to build and remove habits.

Do not give up easily

There are different cues that lead to giving up. As a software developer you will easily come across

Annoying issues
Poor legacy code
Learning other languages, tools, and domain knowledge
Working with people who have different coding habits, opinion, etc

It is generally a good habit not to give up and keep trying but, don’t be stubborn and understand when is the right time to let go and move on.

When it comes to coding, if you are on the verge of giving up, try following

Take a break and come back later or the next day
Try solving it on paper
Ask for help from those with expertise

Do not copy assignments

When I started my computer science degree, the first C programming assignment was “Write a program that computes x^n (x to power of n) using + (plus) and — (minus) operators where x and n are integers provided by the user”.

It took me a long time with no access to internet to find a solution on paper. I learned not to give up and keep trying and the future assignments become easier and easier.

Do not fall for social network addiction

Believe it or not, a majority of social networks are powered by algorithms that have one goal — Increase the ROI for the company using your time.

Do not lose hope, you are smarter than you think

Lastly, feeling hopeless and worried is going to be a frequent visitor and you will have to learn how to deal with it. Here are a few points in your defense

Don’t let knowledge gap make you worry or hopeless — see article below
Don’t be intimidated by those who are better — You will get there
Don’t lose hope for not knowing everything i.e. AI, Machine Learning, Blockchain, etc — you will learn them eventually

Dan Abramov, one of the developers I follow is the co-creator of famous Redux framework wrote the following article that I consider a great read.

getify

@getify

20+ yrs dev exp, 8 books w/ 100k+ copies sold, 300k+ hours watched of my videos, 4k+ taught in person...

And you know what? I still struggle to get my code to work and it's still a tedious slog. And my code still confuses me the next day.

You're not alone in these struggles.

15:33 PM - 10 Mar 2018

2189 6064

Relevant articles

Finally, some relevant articles for those who wish to read more. One of my favorite articles on 25 Tips for New Developers by Ali
A must-read article Advice to new software developers where he touches on Product vs Consulting company for career/internship.
What New Developers Should Really Focus On by Lydia who also wrote another article that might resonate to new developers.
Some great tips by Stephen on his blog post (Code by hand — my absolute favorite, take breaks when debugging)
Another 15 Tips for Junior Developers by Natasha on her blog (Separate your concerns i.e. SRP, write short methods, find a mentor)
Some amazing tips by Emad on his blog (i.e. contribution to open source, asking asking, writing blogs, etc)

Thank you for reading and sharing your comments! Follow and connect with me over social media networks for future articles.

How to Load Test: A developer’s guide to performance testing

Rafiullah Hamedy — Sat, 27 Jul 2019 05:39:36 +0000

How to design and run load tests using Apache JMeter & Taurus

All code is guilty, until proven innocent. — Anonymous

Objective

The purpose of this article is to help you design and run load test 👍

Why Learn?

As developers we already have the foundational knowledge and with a little effort we could expand our skillset.

Your company cannot afford to hire performance engineers
Not enough testers compared to developers
The skill & knowledge could help you write better and scalable code
Less dependant on other’s expertise

Why Load Testing?

While unit & integration tests ensure code is functionally correct, load testing measures its performance which is equally important.

Only a Load Test can shed light into concurrency issues, whether the database queries make good use of indexes instead of a full table scans, where are the bottlenecks, does the application scale efficiently, what is the application’s response time and throughput and so on.

Getting Started Apache JMeter

In this section we will design and run Apache JMeter load tests.

Environment Setup

For environment, either find a suitable online resource (not recommended), come up with your own simple service (node, python, whatever) or simply use the web service provided in this article.

We will be using a simple java-based spring boot web service that exposes four (4) endpoints. The requirement are Java 1.8 and Apache Maven.

git clone https://github.com/rhamedy/tinyservice4loadtest.git
cd tinyservice4loadtest
mvn spring-boot:run

Apache JMeter

Please go ahead and install Apache JMeter from download site, unzip and execute the following command

apache-jmeter/bin/jmeter.sh       // Linux & MacOS
apache-jmeter/bin/jmeter.bat      // Windows

Design a Test Plan for Apache JMeter

Let’s load test the following apis

http://localhost:8080/students/list  - [GET] List students
http://localhost:8080/students/id    - [GET] Get student by id
http://localhost:8080/students       - [POST] Create student
http://localhost:8080/students/id    - [DELETE] Delete student by id

All the sample tests for above endpoints are available in the GitHub repository.

Step 1

Right click on test plan and pick Add > Threads (Users) > Thread Group. A test plan must have at least 1 Thread Group.

The Number of Threads (users)
The Ramp-Up period (in seconds). How long to reach the max users?
How many times or for how long to run the test

Step 2

Let’s specify what to test. Right Click on ThreadGroup and select Add > Config Elements > HTTP Request Defaults option.

Config Elements are useful if you wish to share configuration among one or more requests for example i.e. server address, port number, token, etc.

Let’s fill out the HTTP Request Defaults Config element

Also let’s add an HTTP Header Manager via Add > Config Elements > HTTP Header Manager for Content-Type header

Step 3

Let’s configure the http requests, Right Click on the ThreadGroup and select Add > Sampler > HTTP Request

What is the method type i.e.GET or POST etc
What is the api path i.e. /students/list or /students etc

Right click to duplicate a request and update it.

Step 4

The Listeners are used to collect results. Right Click on ThreadGroup and select Add > Listener > Summary Report option.

The test plans in words, we create an Apache JMeter Test Plan to Load Test two apis with 50 Users with a ramp-up for a duration of 30 seconds.

If you have the tinyservice4loadtest (or your own) running, then let’s hit the play button and see the results in Summary Report

Run Apache JMeter Test Using CLI

The GUI is not recommended for running complex tests. Let’s open a complex sample test from here.

The above test plan has more elements

The Random Variable generates a value between x and y
The Loop Controller executes the content of loop x times

To generate a meaningful report we need user.properties (Source) in the directory where .jmx test is.

jmeter.reportgenerator.report_title=Apache JMeter Dashboard
jmeter.reportgenerator.overall_granularity=60000
jmeter.reportgenerator.graph.responseTimeDistribution.property.set_granularity=100
jmeter.reportgenerator.apdex_satisfied_threshold=1500
jmeter.reportgenerator.apdex_tolerated_threshold=3000
jmeter.reportgenerator.exporter.html.property.output_dir=/tmp/test-jmeter.reportgenerator.exporter.html.filters_only_sample_series=true

Run the test script using command (output-directory should be empty)

jmeter.sh -n -t loadtest.jmx -l log.jtl -e -o output-directory

In the above command the -n stands for no gui the -t indicates the scripts loadtest.jmx the -l is for log.jtl where -e and -o are for reporting.

The output-directory will contain a bunch of files including an index.html that opens the graphical results of the test as shown below.

In this graph the left side is APDEX and the right side is Request summary. The red indicates all our 404 errors and the green is 200 successful requests.

Some numbers relating to Number of samples, Response time, Throughput

Most importantly the Response Time and Throughput

Lastly, it’s worth-mentioning that Apache JMeter can be configured to listen to a browser’s activity and capture the network request. For details see here.

Getting Started with Taurus

Now that we know how to use Apache JMeter to run a basic load test, let’s explore open-source framework Taurus. In short, one of the reasons for birth of Taurus was because Apache JMeter has a steep learning curve and Taurus make things a lot simpler.

Taurus is an abstraction layer (or a wrapper) on top of Apache JMeter and that means you can run an Apache JMeter script using Taurus. So go ahead and install Taurus using the easy to install instruction

The Taurus scripts can be written in YAML or JSON using follow blocks

Scenarios is basically where one or more requests are defined. For each scenario an execution is defined with props such as no of users, duration, ramp-up period and so on. The modules allow us to configure executor that could be Apache JMeter, Selenium and so on. Likewise, the reporting allows configuring how the report should be generated i.e. csv, live reporting in console, or push the result to the blazemeter website.

scenarios: 
 StudentList: 
  requests: 
   - url: http://localhost:8080/students/list
     label: Student List
execution: 
 - scenario: StudentList 
   concurrency: 15
   ramp-up: 2s
   hold-for: 10s
reporting:
 - module: console 
 - module: final-stats 
   summary: true 
   percentiles: true
   test-duration: true 
   dump-csv: single_scenario_single_req.csv

Load test /students/list api reaching 15 users within 2s (ramp-up) for a duration of 10s and display live result in the console as well as csv file.

To run the Taurus test (sample provided here), simply run the command bzt test.yaml

In a Taurus test you can also configure a scenario to point to an Apache JMeter script and override execution and other parameters.

scenarios: 
 JMeterExample: 
  script: student_crud_jmeter.jmx

Taurus seems to be a very interesting framework and it is worth checking it out. It is very well-documented here.

Conclusion

I highly recommend checking out Apache JMeter and Taurus documentations if you wish you learn more techniques and tricks.

Read some of my other articles on Medium

Note: I am thinking of moving away from Medium because of their Paywall. I see a huge difference in stats of my stories before and after introduction of the Paywall. I prefer my articles to be accessible at no cost.

Feel free to connect and follow me on your favourite social media for future articles.

DEV Community: Rafiullah Hamedy

JUnit 4 & 5 Annotations Every Developer Should Know

A Summary of JUnit 4 & 5 Annotations with Examples

What to expect?

rhamedy / junit-annotations-examples

JUnit 4 and 5 Annotations with Examples

JUnit 4

JUnit 5

JUnit Dependencies

JUnit Annotations Usage

The Hello World of Unit Testing

The Class-Level and Test-Level Annotations

Ignoring a Test vs. Assumption

Executing Tests in Order

Adding Timeout to Tests

Using Rule with JUnit Tests

ExpectedException Rule

TemporaryFolder Rule

ErrorCollector Rule

JUnit Suites

Categories in JUnit 4

Tagging & Filtering Tests in JUnit 5

Parametrizing Unit Tests

Parameterized Tests with a ValueSource

Parameterized Tests with an EnumSource

Parameterized Tests with a MethodSource

Parameterized Tests with a CSV Sources

Theory in JUnit4

JUnit 5 Test DisplayName

Repeating a JUnit Test

Executing Inner Class Unit Tests using JUnit 5's Nested

JUnit 5 Test Lifecycle with TestInstance Annotation

DynamicTests using JUnit 5 TestFactory Annotation

Conditionally Executing JUnit 5 Tests

Conclusion

Why you should think twice about contributing to Open Source

Rafiullah Hamedy ・ Aug 22 '19 ・ 7 min read

Key habits and things I wish I knew earlier as a developer

Rafiullah Hamedy ・ Aug 6 '19 ・ 9 min read

A short summary of Java coding best practices | by Rafiullah Hamedy | Medium

Rafiullah Hamedy ・ Aug 18, 2020 ・ 14 min read Medium

Contribution Debt: Why & How to Contribute to Stack Overflow

Why & How to Stop Procrastinating and Start Contributing

Why do I contribute?

How to contribute?

Ask questions

Answer questions

Answer your own questions

Issue

Upvoting and downvoting posts

What are the benefits of contributing?

Conclusion

Why you should think twice about contributing to Open Source

Rafiullah Hamedy ・ Aug 22 '19

Key habits and things I wish I knew earlier as a developer

Rafiullah Hamedy ・ Aug 6 '19

Why you should think twice about contributing to Open Source

7 out of 10 developers contribute to open source and here are some tips and suggestions on how to get started

Why should you care?

Reasons why I failed to contribute earlier?

My Motivation

Key habits and things I wish I knew earlier as a developer

Rafiullah Hamedy ・ Aug 6 '19

My Contribution Strategy

Add Clear Site Data to Log Out #4187

Add Support for Clear Site Data on Logout #6550

Tips and Suggestions

Recommended Reading

Key habits and things I wish I knew earlier as a developer

A listing of key habits and skills that could help you become a better developer

Summary

Learning

Search efficiently

Development IDEs

Learn Linux

Learn Git

Teach Yourself

Learn at least one language concretely

Focus on Simplicity

Coding Standards Matter

Rafiullah Hamedy ・ Aug 18, 2020 ・ 14 min read
Medium