Bug 1907846 - Change how our eslint-plugin-* modules determine the root source directory. r=frontend-codestyle-reviewers,mossop

This switches to checking for the package.json whose name is mozilla-central, which should be more
reliable than checking for .eslintignore, and ensures that we're compatible with flat config which
will remove .eslintignore.

Differential Revision: https://phabricator.services.mozilla.com/D216538

tools/lint/eslint/eslint-plugin-mozilla/lib/helpers.js

@@ -634,17 +634,23 @@ module.exports = {
 
   /**
    * Gets the root directory of the repository by walking up directories from
-   * this file until a .eslintignore file is found. If this fails, the same
-   * procedure will be attempted from the current working dir.
+   * this file until the top-level mozilla-central package.json file is found.
+   * If this fails, the same procedure will be attempted from the current
+   * working dir.
+   *
    * @return {String} The absolute path of the repository directory
    */
   get rootDir() {
     if (!gRootDir) {
-      function searchUpForIgnore(dirName, filename) {
+      function searchUpForPackage(dirName) {
         let parsed = path.parse(dirName);
         while (parsed.root !== dirName) {
-          if (fs.existsSync(path.join(dirName, filename))) {
-            return dirName;
+          let possibleFile = path.join(dirName, "package.json");
+          if (fs.existsSync(possibleFile)) {
+            let packageData = require(possibleFile);
+            if (packageData.name == "mozilla-central") {
+              return dirName;
+            }
           }
           // Move up a level
           dirName = parsed.dir;
@@ -653,15 +659,9 @@ module.exports = {
         return null;
       }
 
-      let possibleRoot = searchUpForIgnore(
-        path.dirname(module.filename),
-        ".eslintignore"
-      );
+      let possibleRoot = searchUpForPackage(path.dirname(module.filename));
       if (!possibleRoot) {
-        possibleRoot = searchUpForIgnore(path.resolve(), ".eslintignore");
-      }
-      if (!possibleRoot) {
-        possibleRoot = searchUpForIgnore(path.resolve(), "package.json");
+        possibleRoot = searchUpForPackage(path.resolve());
       }
       if (!possibleRoot) {
         // We've couldn't find a root from the module or CWD, so lets just go

tools/lint/eslint/eslint-plugin-spidermonkey-js/lib/environments/self-hosted.js

@@ -13,14 +13,26 @@ const fs = require("fs");
 
 let gRootDir = null;
 
-// Copied from `tools/lint/eslint/eslint-plugin-mozilla/lib/helpers.js`.
+/**
+ * Gets the root directory of the repository by walking up directories from
+ * this file until the top-level mozilla-central package.json file is found.
+ * If this fails, the same procedure will be attempted from the current
+ * working dir.
+ * Copied from `tools/lint/eslint/eslint-plugin-mozilla/lib/helpers.js`.
+ *
+ * @return {String} The absolute path of the repository directory
+ */
 function getRootDir() {
   if (!gRootDir) {
-    function searchUpForIgnore(dirName, filename) {
+    function searchUpForPackage(dirName) {
       let parsed = path.parse(dirName);
       while (parsed.root !== dirName) {
-        if (fs.existsSync(path.join(dirName, filename))) {
-          return dirName;
+        let possibleFile = path.join(dirName, "package.json");
+        if (fs.existsSync(possibleFile)) {
+          let packageData = require(possibleFile);
+          if (packageData.name == "mozilla-central") {
+            return dirName;
+          }
         }
         // Move up a level
         dirName = parsed.dir;
@@ -28,16 +40,9 @@ function getRootDir() {
       }
       return null;
     }
-
-    let possibleRoot = searchUpForIgnore(
-      path.dirname(module.filename),
-      ".eslintignore"
-    );
+    let possibleRoot = searchUpForPackage(path.dirname(module.filename));
     if (!possibleRoot) {
-      possibleRoot = searchUpForIgnore(path.resolve(), ".eslintignore");
-    }
-    if (!possibleRoot) {
-      possibleRoot = searchUpForIgnore(path.resolve(), "package.json");
+      possibleRoot = searchUpForPackage(path.resolve());
     }
     if (!possibleRoot) {
       // We've couldn't find a root from the module or CWD, so lets just go