Bug/6790 validator incorrect text (#6808)

* Add unit test #6790

* Validator text containing an expression doesn't update properly on value change fix #6790

src/question.ts

@@ -1840,6 +1840,9 @@ export class Question extends SurveyElement<Question>
         this.survey.beforeSettingQuestionErrors(this, errors);
       }
       this.errors = errors;
+      if(this.errors !== errors) {
+        this.errors.forEach(er => er.locText.strChanged());
+      }
     }
     this.updateContainsErrors();
     if (oldHasErrors != errors.length > 0) {

src/survey-error.ts

@@ -44,7 +44,7 @@ export class SurveyError {
     return surveyLocalization.getString(locStrName, this.getLocale());
   }
   public onUpdateErrorTextCallback: (error: SurveyError) => void = undefined;
-  public updateText() {
+  public updateText(): void {
     if(this.onUpdateErrorTextCallback) {
       this.onUpdateErrorTextCallback(this);
     }

tests/surveyquestiontests.ts

@@ -7090,4 +7090,45 @@ QUnit.test("Try to set incorrect values, bug#6629", function (assert) {
   assert.equal(q5.isEmpty(), true, "Can't set 'e' to multipletext");
   assert.deepEqual(q6.value, ["f"], "Convert to array");
   ConsoleWarnings.inCorrectQuestionValue = oldFunc;
-});
+});
+QUnit.test("Dynamic error text in expression validator, bug#6790", function (assert) {
+  const survey = new SurveyModel({
+    checkErrorsMode: "onValueChanged",
+    elements: [
+      {
+        type: "text",
+        name: "q1",
+        isRequired: true
+      },
+      {
+        type: "expression",
+        name: "q2",
+        expression: "100 - {q1}",
+        validators: [
+          {
+            type: "expression",
+            text: "{q2}% left.",
+            expression: "{leftover} <= 0"
+          }
+        ]
+      }
+    ]
+  });
+  const q1 = survey.getQuestionByName("q1");
+  const q2 = survey.getQuestionByName("q2");
+  q1.value = 10;
+  assert.equal(q2.errors.length, 1, "Error is here, #1");
+  const error = q2.errors[0];
+  assert.equal(q2.errors[0].locText.renderedHtml, "90% left.", "Error text is correct, #1");
+  let errorTextChangedCounter = 0;
+  error.locText.onChanged = (): void => {
+    errorTextChangedCounter ++;
+  };
+  q1.value = 20;
+  assert.equal(q2.errors.length, 1, "Error is here, #2");
+  assert.equal(q2.errors[0].locText.renderedHtml, "80% left.", "Error text is correct, #2");
+  assert.equal(error.locText.renderedHtml, "80% left.", "Old error text is correct, #2");
+  assert.strictEqual(error, q2.errors[0], "Same errors");
+  assert.equal(errorTextChangedCounter, 1, "text has been updated");
+});
+