Add and pass one regression test for radio widget parser (#1871)

This PR is a "pilot" demonstrating how regression testing for the PerseusItem
parser will work. The regression test uses production data found by running the
[exhaustive test tool][1].

[1]: #1864

Issue: LEMS-2582

## Test plan:

`yarn test`

Author: benchristel

Reviewers: benchristel, mark-fitzgerald, jeremywiebe, anakaren-rojas, catandthemachines, nishasy

Required Reviewers:

Approved By: jeremywiebe

Checks: ✅ Publish npm snapshot (ubuntu-latest, 20.x), ✅ Lint, Typecheck, Format, and Test (ubuntu-latest, 20.x), ✅ Check builds for changes in size (ubuntu-latest, 20.x), ✅ Cypress (ubuntu-latest, 20.x), ✅ Publish Storybook to Chromatic (ubuntu-latest, 20.x), ✅ Check for .changeset entries for all changed files (ubuntu-latest, 20.x), ✅ gerald

Pull Request URL: #1871

.changeset/mean-pens-grow.md

@@ -0,0 +1,5 @@
+---
+"@khanacademy/perseus": patch
+---
+
+Internal: Add regression tests for PerseusItem parser

packages/perseus/src/util/parse-perseus-json/perseus-parsers/radio-widget.ts

@@ -43,6 +43,6 @@ export const parseRadioWidget: Parser<RadioWidget> = parseWidget(
         displayCount: optional(any),
         // v0 props
         // `noneOfTheAbove` is still in use (but only set to `false`).
-        noneOfTheAbove: constant(false),
+        noneOfTheAbove: optional(constant(false)),
     }),
 );

packages/perseus/src/util/parse-perseus-json/regression-tests/data/radio-missing-noneOfTheAbove.json

@@ -0,0 +1,48 @@
+{
+  "question": {
+    "content": "$\\begin{align} \nA &= \\{x: x \\text{ is a rectangle in the plane P} \\} \\\\\\\\\nB &= \\{x: x \\text{ is a square in the plane P} \\}\n\\end{align}$\n\n**Is $A \\subset B$ ?**\n\n[[☃ radio 1]]\n",
+    "images": {},
+    "widgets": {
+      "radio 1": {
+        "type": "radio",
+        "alignment": "default",
+        "static": false,
+        "graded": true,
+        "options": {
+          "choices": [
+            {
+              "content": "Yes",
+              "correct": false
+            },
+            {
+              "content": "No",
+              "correct": true
+            }
+          ],
+          "randomize": false,
+          "multipleSelect": false,
+          "countChoices": false,
+          "displayCount": null,
+          "hasNoneOfTheAbove": false,
+          "deselectEnabled": false
+        },
+        "version": {
+          "major": 1,
+          "minor": 0
+        }
+      }
+    }
+  },
+  "answerArea": {
+    "calculator": false,
+    "chi2Table": false,
+    "periodicTable": false,
+    "tTable": false,
+    "zTable": false
+  },
+  "itemDataVersion": {
+    "major": 0,
+    "minor": 1
+  },
+  "hints": []
+}

packages/perseus/src/util/parse-perseus-json/regression-tests/parse-perseus-json-regression.test.ts

@@ -0,0 +1,20 @@
+import * as fs from "fs";
+import {join} from "path";
+
+import {parseAndTypecheckPerseusItem} from "../index";
+
+const dataFiles = fs.readdirSync(join(__dirname, "data"));
+
+describe("parseAndTypecheckPerseusItem", () => {
+    it.each(dataFiles)("accepts data/%s", (filename) => {
+        const json = fs.readFileSync(
+            join(__dirname, "data", filename),
+            "utf-8",
+        );
+        const result = parseAndTypecheckPerseusItem(json);
+
+        // This strange-looking assertion style results in the failure message
+        // being printed if parsing fails, so the test is easier to debug.
+        expect(result).toEqual(expect.objectContaining({type: "success"}));
+    });
+});