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Building a Test Plan Programmatically

> JMeter 5.6 brings experimental classes and methods to build test plans programmatically, so please feel free to provide your feedback.

> In this section, you will learn how to create a Test Plan with JMeter APIs.

> The Test Plan is a collection of elements arranged in a tree-like manner. However, in JMeter APIs, the elements do not form a tree. Parent-child relationships are stored in a separate structure: `ListedHashTree`.

Creating a plan with low-level APIs

> Let us create `Test Plan => Thread Group => Debug Sampler` plan

>     ListedHashTree root = new ListedHashTree(); // (1)
>     TestPlan testPlan = new TestPlan();
>     ListedHashTree testPlanSubtree = root.add(testPlan); // (2)
>     TestPlan threadGroup = new ThreadGroup();
>     threadGroup.setName("Search Order Thread Group");
>     ListedHashTree threadGroupSubtree = testPlanSubtree.add(threadGroup); // (3)
>     DebugSampler debugSampler = new DebugSampler();
>     threadGroupSubtree.add(debugSampler);

> - Firstly, we create the tree at `(1)`
> - Then we create elements, and add them to the tree in `(2)`
> - Note how adding element returns the subtree, so we add `threadGroup` under `testPlan` in `(2)`

> Don't confuse `ListedHashTree` with `HashTree`. `HashTree` does not honour element order, so the generated elements might shuffle unexpectedly.

Generating code from UI

> To aid with creating code, JMeter implements `Copy Code` context action, so you could generate code for any element in the plan. It would generate code for the element and its children.

> Copy Code context action

> Here's the generated code (Kotlin DSL):

>     org.apache.jmeter.protocol.http.sampler.HTTPSamplerProxy::class {
>         props {
>             it[arguments] = org.apache.jmeter.config.Arguments().apply {
>                 props {
>                     it[arguments] = listOf(
>                         org.apache.jmeter.protocol.http.util.HTTPArgument().apply {
>                             props {
>                                 it[value] = "World"
>                                 it[metadata] = "="
>                                 it[useEquals] = true
>                                 it[argumentName] = "user"
>                             }
>                         },
>                         org.apache.jmeter.protocol.http.util.HTTPArgument().apply {
>                             props {
>                                 it[alwaysEncode] = true
>                                 it[value] = "test_value"
>                                 it[metadata] = "="
>                                 it[useEquals] = true
>                                 it[argumentName] = "test"
>                             }
>                         },
>                     )
>                     it[name] = "User Defined Variables"
>                     it[guiClass] = "org.apache.jmeter.protocol.http.gui.HTTPArgumentsPanel"
>                     it[testClass] = "org.apache.jmeter.config.Arguments"
>                 }
>             }
>             it[domain] = "example.com"
>             it[path] = "/api/v1/login"
>             it[method] = "GET"
>             it[followRedirects] = true
>             it[useKeepalive] = true
>             it[proxy.scheme] = "https"
>             it[proxy.host] = "localhost"
>             it[proxy.port] = "8080"
>             it[proxy.username] = "secret"
>             it[proxy.password] = "password1"
>             it[name] = "/login"
>             it[guiClass] = "org.apache.jmeter.protocol.http.control.gui.HttpTestSampleGui"
>         }

>         org.apache.jmeter.extractor.RegexExtractor::class {
>             props {
>                 it[guiClass] = "org.apache.jmeter.extractor.gui.RegexExtractorGui"
>                 it[name] = "extract user id"
>                 it[referenceName] = "regexVar"
>                 it[regularExpression] = "hello\\s+?world"
>                 it[template] = "\$1\$"
>             }
>         }

>         org.apache.jmeter.protocol.http.control.HeaderManager::class {
>             props {
>                 it[headers] = listOf(
>                     org.apache.jmeter.protocol.http.control.Header().apply {
>                         props {
>                             it[headerName] = "Accept"
>                             it[value] = "text/plain"
>                         }
>                     },
>                     org.apache.jmeter.protocol.http.control.Header().apply {
>                         props {
>                             it[headerName] = "User-Agent"
>                             it[value] = "JMeter"
>                         }
>                     },
>                     org.apache.jmeter.protocol.http.control.Header().apply {
>                         props {
>                             it[headerName] = "X-JMeter-Thread"
>                             it[value] = "Thread \${__threadNum}"
>                         }
>                     },
>                 )
>                 it[guiClass] = "org.apache.jmeter.protocol.http.gui.HeaderPanel"
>                 it[name] = "HTTP Header Manager"
>             }
>         }
>     }

Creating a plan with Kotlin DSL

> JMeter 5.6 introduces Kotlin DSL which might make it easier to create and maintain test plans as the structure of the code would resemble the structure of the generated test plan tree

>     import org.apache.jmeter.sampler.DebugSampler
>     import org.apache.jmeter.testelement.TestPlan
>     import org.apache.jmeter.threads.ThreadGroup
>     import org.apache.jmeter.treebuilder.dsl.testTree

>     val root = testTree { // (1)
>       TestPlan::class { // (2)
>         ThreadGroup::class {
>            name = "Search Order Thread Group"
>            +DebugSampler::class // (3)
>            +DebugSampler() // (4)
>         }
>       }
>     }

> - Firstly, we create a `TreeBuilder` at `(1)`
> - Then we add elements to the tree in `(2)`, and populate its children
> - Note how adding element returns the subtree, so we add `threadGroup` under `testPlan` in `(2)`
> - If no children needed, the element can be appended to the tree with a unary plus operator as in `(3)`
> - By default, JMeter uses no-argument constructors to create elements, however, you can add `TestElement` instances to the tree as well, see `(4)`

Extending Kotlin DSL

> As you use the DSL for test plan generation, you might want to factor out the common patterns. For instance, imagine you want factor out `Thread Group` creation so it always has a `Summariser` element.

>     import kotlin.time.Duration.Companion.seconds
>     import org.apache.jmeter.sampler.DebugSampler
>     import org.apache.jmeter.testelement.TestPlan
>     import org.apache.jmeter.threads.ThreadGroup
>     import org.apache.jmeter.treebuilder.dsl.testTree

>     fun TreeBuilder.threadGroup( // (1)
>         name: String,
>         numThreads: Int = 10,
>         rampUp: Duration = 3.seconds,
>         body: Action<ThreadGroup>
>     ) {
>         ThreadGroup::class { // (2)
>             this.name = name
>             this.numThreads = numThreads
>             this.rampUp = rampUp.inWholeSeconds.toInt()
>             +Summariser::class
>             body(this) // (3)
>         }
>     }

>     fun buildTree() {
>       val root = testTree {
>         TestPlan::class {
>           threadGroup(name = "Search Order Thread Group", rampUp = 1.seconds) { // (4)
>              +DebugSampler::class
>           }
>         }
>       }

> - Firstly, you can factor test element creation logic as an extension function for `TreeBuilder` as in `(1)`. It uses regular DSL to add an element (see `(2)`), and then it calls the lambda body in `(3)` to fill thread group children.
> - You can use the extension by calling it when you need it in the test plan, see `(4)`
> - Note how named parameters, and default values keep the code readable

Creating a plan with Java DSL

> JMeter 5.6 introduces Java DSL which might make it easier to create and maintain test plans as the structure of the code would resemble the structure of the generated test plan tree

>     import org.apache.jmeter.sampler.DebugSampler
>     import org.apache.jmeter.testelement.TestPlan
>     import org.apache.jmeter.threads.ThreadGroup
>     import static org.apache.jmeter.treebuilder.dsl.TreeBuilders.testTree

>     ListedHashTree root = testTree(b -> { // (1)
>       b.add(TestPlan.class, tp -> { // (2)
>         b.add(ThreadGroup.class, tg -> {
>            tg.setName("Search Order Thread Group");
>            b.add(DebugSampler.class); // (3)
>            b.add(new DebugSampler()); // (4)
>         });
>       });
>     });

> - Firstly, we create a `TreeBuilder` at `(1)`. Note how this builder reference should be used to append all the elements
> - Then we add elements to the tree in `(2)`, and populate its children. The lambda parameters correspond to the added elements, so you can configure their properties
> - Note how adding element returns the subtree, so we add `threadGroup` under `testPlan` in `(2)`
> - If no children needed, you could omit the lambda parameter as in `(3)`
> - By default, JMeter uses no-argument constructors to create elements, however, you can add `TestElement` instances to the tree as well, see `(4)`

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