Add random choice support for WeightedSwitchController

- Added `isRandomChoice()` method to DslWeightedSwitchController to enable
  random selection of child elements
- Added test case to verify random choice functionality

Author: kopysov

jmeter-java-dsl/src/main/java/us/abstracta/jmeter/javadsl/core/controllers/DslWeightedSwitchController.java

@@ -44,6 +44,7 @@
 public class DslWeightedSwitchController extends BaseController<DslWeightedSwitchController> {
 
   public static final long DEFAULT_WEIGHT = 100;
+  private boolean isRandomChoice = false;
 
   public DslWeightedSwitchController() {
     super("Weighted Switch Controller", WeightedSwitchControllerGui.class, new ArrayList<>());
@@ -80,6 +81,11 @@ public DslWeightedSwitchController child(long weight, DslSampler child) {
     return addWeightedChild(weight, child);
   }
 
+  public DslWeightedSwitchController isRandomChoice(){
+    this.isRandomChoice = true;
+    return this;
+  }
+
   private DslWeightedSwitchController addWeightedChild(long weight, ThreadGroupChild child) {
     children.add(new WeightedChild(weight, child));
     return this;
@@ -144,6 +150,7 @@ public HashTree buildTreeUnder(HashTree parent, BuildTreeContext context) {
       }
     }
     controller.setData(model);
+    controller.setIsRandomChoice(isRandomChoice);
     return ret;
   }
 

jmeter-java-dsl/src/test/java/us/abstracta/jmeter/javadsl/core/controllers/DslWeightedSwitchControllerTest.java

@@ -44,6 +44,29 @@ public void shouldOnlyExecuteGivenPercentOfTheTimesWhenInPlan() throws Exception
             new WeightedLabel(label3, weight2)));
   }
 
+  @Test
+  public void shouldHandleRandomChoiceWhenInPlan() throws Exception {
+    int threads = 1;
+    int iterations = 20;
+    long weight1 = 60;
+    long weight2 = 30;
+    String label3 = "sample3";
+
+    TestPlanStats stats = testPlan(
+            threadGroup(threads, iterations,
+                    weightedSwitchController()
+                            .child(weight1, httpSampler(SAMPLE_1_LABEL, wiremockUri))
+                            .children(httpSampler(SAMPLE_2_LABEL, wiremockUri))
+                            .child(weight2, httpSampler(label3, wiremockUri))
+                            .isRandomChoice()
+            )
+    ).run();
+
+    Map<String, Long> sampleCounts = buildSampleCountsMap(stats);
+    assertThat(sampleCounts.keySet()).containsExactlyInAnyOrder(SAMPLE_1_LABEL, SAMPLE_2_LABEL, label3);
+  }
+
+
   private Map<String, Long> buildSampleCountsMap(TestPlanStats stats) {
     return stats.labels().stream()
         .collect(Collectors.toMap(s -> s, s -> stats.byLabel(s).samplesCount()));