Spock is able to change the execution order of test methods in a specification. We can tell Spock to re-run failing methods before successful methods. And if we have multiple failing or successful tests, than first run the fastest methods, followed by the slower methods. This way when we re-run the specification we immediately see the failing methods and could stop the execution and fix the errors. We must set the property optimizeRunOrder in the runner configuration of the Spock configuration file. A Spock configuration file with the name SpockConfig.groovy can be placed in the classpath of our test execution or in our USER_HOME/.spock directory. We can also use the Java system property spock.configuration and assign the filename of our Spock configuration file.

In the following example we have a specification with different methods that can be successful or fail and have different durations when executed:

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When we execute a Gradle test task in IntelliJ IDEA the IDE test runner is used. This means we can get a nice overview of all tests that have run. If a test is successful we get a green light, otherwise it is red in case of an error or orange in case of a failure. Gradle also generates a nice HTML report when we run the test task. It is placed in the directory build/reports/tests/. IntelliJ IDEA has a button which opens this report when we click on it. The following screenshot shows the button with the tooltip that opens a Gradle test report:

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In a previous post we saw how can use the Spock configuration file to include or exclude specifications based on annotations. Instead of using annotations we can also use classes to include or exclude specifications. For example we could have a base specification class DatabaseSpecification. Other specifications dealing with databases extend this class. To include all these specifications we use the DatabaseSpecification as value for the include property for the test runner configuration.

Because Java (and Groovy) doesn't support real multiple inheritance this might be a problem if we already have specifications that extends a base class, but the base class cannot be used as filter for the include and exclude runner configuration. Luckily we can also use an interface as the value for the inclusion or exclusion. So we could simple create a marker interface and implement this interface for these specifications we want to include or exclude from the test execution.

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One of the lesser known and documented features of Spock if the external Spock configuration file. In this file we can for example specify which specifications to include or exclude from a test run. We can specify a class name (for example a base specification class, like DatabaseSpec) or an annotation. In this post we see how to use annotations to have some specifications run and others not.

The external Spock configuration file is actually a Groovy script file. We must specify a runner method with a closure argument where we configure basically the test runner. To include specification classes or methods with a certain annotation applied to them we configure the include property of the test runner. To exclude a class or method we use the exclude property. Because the configuration file is a Groovy script we can use everything Groovy has to offer, like conditional statements, println statements and more.

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Logback is a SLF4J API implementation for logging messages in Java and Groovy. We can configure Logback with a Groovy configuration file. The file is a Groovy script and allows for a nice an clean way (no XML) to configure Logback. If we want to show the logging configuration and see how Logback is configured we must add a StatusListener implementation in our configuration. The StatusListener implementation prints out the configuration when our application starts. Logback provides a StatusListener for outputting the information to system out or system error streams (OnConsoleStatusListener and OnErrorConsoleStatusListener). If we want to disable any status messages we use the NopStatusListener class.

In the following example configuration file we define the status listener with the statusListener method. We use the OnConsoleStatusListener in our example:

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When we use Logback as SLF4J API implementation in our code we can have our logging output send to our console. By default the standard output is used to display the logging output. We can alter the configuration and have the logging output for the console send to standard error. This can be useful when we use a framework that uses the standard output for communication and we still want to see logging from our application on the console. We set the property target for the ConsoleAppender to the value System.err instead of the default System.out. The following sample Logback configuration in Groovy send the logging output to the console and standard error:

appender("SystemErr", ConsoleAppender) {
    // Enable coloured output.
    withJansi = true

    encoder(PatternLayoutEncoder) {
        pattern = "%blue(%-5level) %green(%logger{35}) - %msg %n"
    }

    // Redirect output to the System.err.
    target = 'System.err'

}

root(DEBUG, ["SystemErr"])

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Gradle introduced the continuous build feature in version 2.5. The feature is still incubating, but we can already use it in our daily development. The continuous build feature means Gradle will not shut down after a task is finished, but keeps running and looks for changes to files to re-run tasks automatically. It applies perfectly for a scenario where we want to re-run the test task while we write our code. With the continuous build feature we start Gradle once with the test task and Gradle will automatically recompile source files and run tests if a source file changes.

To use the continuous build feature we must use the command line option --continuous or the shorter version -t. With this option Gradle will start up in continuous mode. To stop Gradle we must use the Ctrl+D key combination.

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In a previous blog post we made an API with spray. Now we're going to load test it. For this, we will use http://gatling.io/#/. In a scala class we can write exactly what and how we want to run the test. In this test, we will do a post to our API and create a new robot called C3PO. We will do this 1000 times per second and keep doing this for 10 seconds. For a total of 10000 C3POs! RobotsLoadTest.scala:

import io.gatling.core.Predef._
import io.gatling.http.Predef._
import scala.concurrent.duration._

class RobotsLoadTest extends Simulation {
    val baseUrl = "http://localhost:8080" //We need to have our API running here

    val httpProtocol = http
        .baseURL(baseUrl)
        .inferHtmlResources()
        .acceptEncodingHeader("gzip,deflate")
        .contentTypeHeader("application/json")
        .userAgentHeader("Apache-HttpClient/4.1.1 (java 1.5)")

    val s = scenario("Simulation")
        .exec(http("request_0")
        .post("/robots")
        .body(StringBody("""{
                        |  "name": "C3PO",
                        |  "amountOfArms": 2
                        |}""".stripMargin))
        )

    setUp(s.inject(constantUsersPerSec(1000) during(10 seconds))).protocols(httpProtocol)
}

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Suppose I have a List of things on which I want to do something that may fail. In this example I have a List of Strings that I want to turn into a List of Integers.

val strings = List("1", "bla", "4")

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