From 82fea356228015de681da47143f0feb4842f318e Mon Sep 17 00:00:00 2001
From: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>
Date: Tue, 9 Jan 2024 04:25:07 +0100
Subject: [PATCH] feat(python): show custom message if syntax error (#53040)

---
 client/i18n/locales/english/translations.json     |  1 +
 .../Challenges/redux/execute-challenge-saga.js    |  5 ++++-
 .../browser-scripts/python-test-evaluator.ts      | 15 ++++++++++++++-
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/client/i18n/locales/english/translations.json b/client/i18n/locales/english/translations.json
index 0a565f7e834..80ab3e87a48 100644
--- a/client/i18n/locales/english/translations.json
+++ b/client/i18n/locales/english/translations.json
@@ -373,6 +373,7 @@
     "running-tests": "// running tests",
     "tests-completed": "// tests completed",
     "console-output": "// console output",
+    "syntax-error": "Your code raised a error before we could run any tests. Please fix it and try again.",
     "sign-in-save": "Sign in to save your progress",
     "download-solution": "Download my solution",
     "download-results": "Download my results",
diff --git a/client/src/templates/Challenges/redux/execute-challenge-saga.js b/client/src/templates/Challenges/redux/execute-challenge-saga.js
index 31f0f8da0a2..d2516f46e5d 100644
--- a/client/src/templates/Challenges/redux/execute-challenge-saga.js
+++ b/client/src/templates/Challenges/redux/execute-challenge-saga.js
@@ -209,7 +209,7 @@ function* executeTests(testRunner, tests, testTimeout = 5000) {
         throw err;
       }
     } catch (err) {
-      const { actual, expected } = err;
+      const { actual, expected, syntaxError } = err;
 
       newTest.message = text
         .replace('--fcc-expected--', expected)
@@ -217,6 +217,9 @@ function* executeTests(testRunner, tests, testTimeout = 5000) {
       if (err === 'timeout') {
         newTest.err = 'Test timed out';
         newTest.message = `${newTest.message} (${newTest.err})`;
+      } else if (syntaxError) {
+        newTest.err = 'syntax error';
+        newTest.message = `<p>${i18next.t('learn.syntax-error')}</p>`;
       } else {
         const { message, stack } = err;
         newTest.err = message + '\n' + stack;
diff --git a/tools/client-plugins/browser-scripts/python-test-evaluator.ts b/tools/client-plugins/browser-scripts/python-test-evaluator.ts
index 412bd102924..7191c8420fc 100644
--- a/tools/client-plugins/browser-scripts/python-test-evaluator.ts
+++ b/tools/client-plugins/browser-scripts/python-test-evaluator.ts
@@ -133,7 +133,20 @@ input = __inputGen(${JSON.stringify(input ?? [])})
 
     // Evaluates the learner's code so that any variables they define are
     // available to the test.
-    runPython(code);
+    try {
+      runPython(code);
+    } catch (err) {
+      // We don't, yet, want user code to raise exceptions. When they do, we
+      // count this as a failing test.
+      ctx.postMessage({
+        err: {
+          message: (err as Error).message,
+          stack: (err as Error).stack,
+          syntaxError: true
+        }
+      });
+      return;
+    }
     // TODO: remove the next line, creating __locals, once all the tests access
     // variables directly.
     runPython('__locals = globals()');