test(curriculum): suppress redundant errors (#33327)

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Closes #33195

curriculum/test/test-challenges.js

@@ -1,4 +1,5 @@
-const assert = require('chai').assert;
+const { assert, AssertionError } = require('chai');
+const Mocha = require('mocha');
 
 const { flatten } = require('lodash');
 const path = require('path');
@@ -26,6 +27,15 @@ const { challengeTypes } = require('../../client/utils/challengeTypes');
 
 const { LOCALE: lang = 'english' } = process.env;
 
+const oldRunnerFail = Mocha.Runner.prototype.fail;
+Mocha.Runner.prototype.fail = function(test, err) {
+  // Don't show stacktrace for assertion errors.
+  if (err.stack && err instanceof AssertionError) {
+    delete err.stack;
+  }
+  return oldRunnerFail.call(this, test, err);
+};
+
 let mongoIds = new MongoIds();
 let challengeTitles = new ChallengeTitles();
 
@@ -127,6 +137,9 @@ const jQueryScript = fs.readFileSync(
         }
 
         it('Test suite must fail on the initial contents', async function() {
+          // suppress errors in the console.
+          const oldConsoleError = console.error;
+          console.error = () => {};
           let fails = (
           await Promise.all(tests.map(async function(test) {
             try {
@@ -141,6 +154,7 @@ const jQueryScript = fs.readFileSync(
               return true;
             }
           }))).some(v => v);
+          console.error = oldConsoleError;
           assert(fails, 'Test suit does not fail on the initial contents');
         });