Randomizing questions on a page no longer works in questionPerPage mode

fix #9385 (#9386)

packages/survey-core/src/page.ts

@@ -279,7 +279,7 @@ export class PageModel extends PanelModel implements IPage {
   get hasShown(): boolean {
     return this.wasShown;
   }
-  public setWasShown(val: boolean) {
+  public setWasShown(val: boolean): void {
     if (val == this.hasShownValue) return;
     this.hasShownValue = val;
     if (this.isDesignMode || val !== true) return;
@@ -289,7 +289,12 @@ export class PageModel extends PanelModel implements IPage {
         (<PanelModelBase><any>els[i]).randomizeElements(this.areQuestionsRandomized);
       }
     }
-    this.randomizeElements(this.areQuestionsRandomized);
+    if(this.randomizeElements(this.areQuestionsRandomized)) {
+      const singleQuestion: any = this.survey?.currentSingleQuestion;
+      if(singleQuestion?.page === this) {
+        this.survey.currentSingleQuestion = this.getFirstVisibleQuestion();
+      }
+    }
   }
   /**
    * Scrolls this page to the top.

packages/survey-core/src/panel.ts

@@ -567,8 +567,8 @@ export class PanelModelBase extends SurveyElement<Question>
     return isRandom && (this.questionOrder !== "initial") || this.questionOrder === "random";
   }
   protected isRandomizing = false;
-  randomizeElements(isRandom: boolean): void {
-    if (!this.canRandomize(isRandom) || this.isRandomizing) return;
+  randomizeElements(isRandom: boolean): boolean {
+    if (!this.canRandomize(isRandom) || this.isRandomizing) return false;
     this.isRandomizing = true;
     var oldElements = [];
     var elements = this.elements;
@@ -580,6 +580,7 @@ export class PanelModelBase extends SurveyElement<Question>
     this.updateRows();
     this.updateVisibleIndexes();
     this.isRandomizing = false;
+    return true;
   }
   /**
    * Returns `true` if elements in this panel/page are arranged in random order.
@@ -1060,6 +1061,13 @@ export class PanelModelBase extends SurveyElement<Question>
     }
     return null;
   }
+  getFirstVisibleQuestion(): Question {
+    const qs = this.questions;
+    for (let i = 0; i < qs.length; i++) {
+      if (qs[i].isVisible) return qs[i];
+    }
+    return null;
+  }
   /**
    * Focuses the first question in this panel/page.
    * @see focusFirstErrorQuestion

packages/survey-core/tests/surveytests.ts

@@ -7812,6 +7812,29 @@ QUnit.test("Randomize questions in page and panels", function (assert) {
 
   Helpers.randomizeArray = oldFunc;
 });
+QUnit.test("Randomize questions in page and panels & single question per page", function (assert) {
+  const oldFunc = Helpers.randomizeArray;
+  Helpers.randomizeArray = HelpTest.randomizeArray;
+
+  const survey = new SurveyModel({
+    questionsOnPageMode: "questionPerPage",
+    questionOrder: "random",
+    pages: [
+      { elements: [{ type: "text", name: "q1" }, { type: "text", name: "q2" }, { type: "text", name: "q3" }] },
+      { elements: [{ type: "text", name: "q4" }, { type: "text", name: "q5" }, { type: "text", name: "q6" }] },
+    ]
+  });
+  const page = survey.pages[0];
+  assert.equal(page.elements[0].name, "q3");
+  assert.equal(page.elements[2].name, "q1");
+  assert.equal(survey.currentSingleQuestion.name, "q3", "The first question is q3");
+  survey.performNext();
+  survey.performNext();
+  survey.performNext();
+  assert.equal(survey.currentSingleQuestion.name, "q6", "The current question is q6");
+
+  Helpers.randomizeArray = oldFunc;
+});
 
 QUnit.test("Quiz, correct, incorrect answers", function (assert) {
   var survey = new SurveyModel({