Bug 2067148 - Add jest at the top-level and switch eslint-plugin-mozilla to use it. r=frontend-codestyle-reviewers,mossop

Differential Revision: https://phabricator.services.mozilla.com/D321861

package.json

@@ -26,6 +26,7 @@
     "eslint-plugin-sdl": "file:tools/lint/eslint/eslint-plugin-sdl-vendored",
     "eslint-plugin-spidermonkey-js": "file:tools/lint/eslint/eslint-plugin-spidermonkey-js",
     "globals": "17.9.0",
+    "jest": "30.4.2",
     "jsdoc": "4.0.5",
     "license-checker-rseidelsohn": "4.4.2",
     "lit": "3.3.3",

taskcluster/kinds/source-test/node.yml

@@ -218,6 +218,7 @@ eslint-plugin-mozilla:
         docker-image: {in-tree: "lint"}
     run:
         command: >
+            cp -r $MOZ_FETCHES_DIR/node_modules node_modules &&
             cp -r $MOZ_FETCHES_DIR/eslint-plugin-mozilla/node_modules tools/lint/eslint/eslint-plugin-mozilla/node_modules &&
             ./mach configure --disable-compile-environment &&
             PATH=$PATH:$MOZ_FETCHES_DIR/node/bin ./mach npm test --prefix tools/lint/eslint/eslint-plugin-mozilla
@@ -227,6 +228,7 @@ eslint-plugin-mozilla:
     fetches:
         toolchain:
             - linux64-node
+            - node-modules
             - eslint-plugin-mozilla
 
 stylelint-plugin-mozilla:

tools/lint/eslint/eslint-plugin-mozilla/jest.config.mjs

@@ -0,0 +1,10 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+export default {
+  testEnvironment: "node",
+  transform: {},
+  testMatch: ["<rootDir>/tests/*.mjs"],
+  reporters: ["<rootDir>/reporters/mozilla-format.js"],
+};

tools/lint/eslint/eslint-plugin-mozilla/package.json

@@ -29,8 +29,7 @@
     "toml-eslint-parser": "1.0.3"
   },
   "devDependencies": {
-    "eslint": "9.39.1",
-    "mocha": "11.8.0"
+    "eslint": "9.39.1"
   },
   "peerDependencies": {
     "eslint": "^9.0.0 || ^10.0.0",
@@ -48,7 +47,7 @@
   },
   "scripts": {
     "prepack": "node scripts/createExports.mjs",
-    "test": "mocha --reporter 'reporters/mozilla-format.js' tests",
+    "test": "NODE_OPTIONS=\"$NODE_OPTIONS --experimental-vm-modules\" NODE_NO_WARNINGS=1 npx jest",
     "postpublish": "rm -f lib/environments/saved-globals.json",
     "update-tooltool": "./update.sh"
   },

tools/lint/eslint/eslint-plugin-mozilla/reporters/mozilla-format.js

@@ -8,53 +8,75 @@
  * mach itself.
  */
 
+/**
+ * @import { Reporter } from "@jest/reporters"
+ * @import { AggregatedResult, Test, TestCaseResult, TestContext } from "@jest/test-result"
+ */
+
 // This is a non-production file that needs to log.
 /* eslint-disable no-console */
 
 "use strict";
 
-var mocha = require("mocha");
 var path = require("path");
-module.exports = MozillaFormatter;
 
-function MozillaFormatter(runner) {
-  mocha.reporters.Base.call(this, runner);
-  var passes = 0;
-  var failures = [];
-
-  runner.on("start", () => {
+/**
+ * A reporter for Jest that outputs results in the format Treeherder expects.
+ *
+ * @implements {Reporter}
+ */
+class MozillaFormatter {
+  onRunStart() {
     console.log("SUITE-START | eslint-plugin-mozilla");
-  });
+  }
 
-  runner.on("pass", function (test) {
-    passes++;
-    let title = test.title.replace(/\n/g, "|");
-    console.log(`TEST-PASS | ${path.basename(test.file)} | ${title}`);
-  });
+  /**
+   * @param {Test} test
+   * @param {TestCaseResult} testCaseResult
+   */
+  onTestCaseResult(test, testCaseResult) {
+    let title = testCaseResult.fullName.replace(/\n/g, "|");
+    let fileName = path.basename(test.path);
 
-  runner.on("fail", function (test, err) {
-    failures.push(test);
-    // Replace any newlines in the title.
-    let title = test.title.replace(/\n/g, "|");
-    console.log(
-      `TEST-UNEXPECTED-FAIL | ${path.basename(test.file)} | ${title} | ${
-        err.message
-      }`
-    );
-    mocha.reporters.Base.list([test]);
-  });
+    if (testCaseResult.status == "passed") {
+      console.log(`TEST-PASS | ${fileName} | ${title}`);
+    } else if (testCaseResult.status == "failed") {
+      let message = testCaseResult.failureMessages[0]?.split("\n")[0];
+      console.log(`TEST-UNEXPECTED-FAIL | ${fileName} | ${title} | ${message}`);
+    }
+  }
 
-  runner.on("end", function () {
+  /**
+   * @param {Set<TestContext>} testContexts
+   * @param {AggregatedResult} results
+   */
+  onRunComplete(testContexts, results) {
     // Space the results out visually with an additional blank line.
     console.log("");
     console.log("INFO | Result summary:");
-    console.log(`INFO | Passed: ${passes}`);
-    console.log(`INFO | Failed: ${failures.length}`);
+    console.log(`INFO | Passed: ${results.numPassedTests}`);
+    console.log(`INFO | Failed: ${results.numFailedTests}`);
     console.log("SUITE-END");
     // Space the failures out visually with an additional blank line.
     console.log("");
     console.log("Failure summary:");
-    mocha.reporters.Base.list(failures);
-    process.exit(failures.length);
-  });
+
+    for (let result of results.testResults) {
+      if (result.numFailingTests) {
+        let fileName = path.basename(result.testFilePath);
+        for (let fileResult of result.testResults) {
+          if (fileResult.status == "failed") {
+            console.log("");
+            let title = fileResult.fullName.replace(/\n/g, "|");
+
+            console.log(
+              `TEST-UNEXPECTED-FAIL | ${fileName} | ${title} | ${fileResult.failureDetails[0]?.message}`
+            );
+          }
+        }
+      }
+    }
+  }
 }
+
+module.exports = MozillaFormatter;