Bug 1944976 - Fix eslint rules to avoid throwing when arguments are missing r=frontend-codestyle-reviewers,Gijs

Avoid some linter rules throwing during validation due to unexpected
argument lengths.
Arguably some of those cases should probably also be caught by other linting
rules.

Differential Revision: https://phabricator.services.mozilla.com/D236271

Author: juliandescottes

tools/lint/eslint/eslint-plugin-mozilla/lib/rules/balanced-observers.js

@@ -41,35 +41,43 @@ module.exports = {
       return api == "obs" || api == "prefs";
     }
 
-    function getObservableName(node, api) {
-      if (api === "obs") {
-        return node.arguments[1].value;
+    function getObservableName(node) {
+      const api = getObserverAPI(node);
+      if (!isServicesObserver(api)) {
+        return null;
+      }
+
+      const observableArgument =
+        api === "obs" ? node.arguments[1] : node.arguments[0];
+      if (!observableArgument) {
+        return null;
       }
-      return node.arguments[0].value;
+
+      return observableArgument.value;
     }
 
     function addAddedObserver(node) {
-      const api = getObserverAPI(node);
-      if (!isServicesObserver(api)) {
+      const observableName = getObservableName(node);
+      if (observableName === null) {
         return;
       }
 
       addedObservers.push({
         functionName: node.callee.property.name,
-        observable: getObservableName(node, api),
+        observable: observableName,
         node: node.callee.property,
       });
     }
 
     function addRemovedObserver(node) {
-      const api = getObserverAPI(node);
-      if (!isServicesObserver(api)) {
+      const observableName = getObservableName(node);
+      if (observableName === null) {
         return;
       }
 
       removedObservers.push({
         functionName: node.callee.property.name,
-        observable: getObservableName(node, api),
+        observable: observableName,
       });
     }
 
@@ -90,10 +98,6 @@ module.exports = {
 
     return {
       CallExpression(node) {
-        if (node.arguments.length === 0) {
-          return;
-        }
-
         if (node.callee.type === "MemberExpression") {
           var methodName = node.callee.property.name;
 

tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-addtask-setup.js

@@ -32,6 +32,7 @@ module.exports = {
         if (callee.type === "Identifier" && callee.name === "add_task") {
           let arg = node.arguments[0];
           if (
+            !arg ||
             arg.type !== "FunctionExpression" ||
             !arg.id ||
             !isNamedLikeSetup(arg.id.name)

tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-comparison-or-assignment-inside-ok.js

@@ -45,7 +45,7 @@ module.exports = {
           return;
         }
         let firstArg = node.arguments[0];
-        if (!exprs.has(firstArg.type)) {
+        if (!firstArg || !exprs.has(firstArg.type)) {
           return;
         }
         if (firstArg.type == "AssignmentExpression") {

tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-cu-reportError.js

@@ -111,6 +111,7 @@ module.exports = {
               // into multiple arguments instead:
               if (
                 checkNode == node.callee &&
+                node.arguments.length >= 1 &&
                 isConcatenation(node.arguments[0])
               ) {
                 let { fixes: recursiveFixes } = replaceConcatWithComma(

tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-useless-removeEventListener.js

@@ -53,6 +53,7 @@ module.exports = {
           call.callee.type == "MemberExpression" &&
           call.callee.property.type == "Identifier" &&
           call.callee.property.name == "removeEventListener" &&
+          call.arguments[0] &&
           ((call.arguments[0].type == "Literal" &&
             call.arguments[0].value == node.arguments[0].value) ||
             (call.arguments[0].type == "Identifier" &&

tools/lint/eslint/eslint-plugin-mozilla/lib/rules/reject-importGlobalProperties.js

@@ -54,7 +54,8 @@ module.exports = {
           // Only Cu, not Components.utils as `use-cc-etc` handles this for us.
           memexp.object.name === "Cu" &&
           memexp.property.type === "Identifier" &&
-          memexp.property.name === "importGlobalProperties"
+          memexp.property.name === "importGlobalProperties" &&
+          node.arguments.length >= 1
         ) {
           if (context.options.includes("allownonwebidl")) {
             for (let element of node.arguments[0].elements) {

tools/lint/eslint/eslint-plugin-mozilla/lib/rules/valid-lazy.js

@@ -143,7 +143,8 @@ module.exports = {
           node.id.type === "Identifier" &&
           node.id.name == "lazy" &&
           node.init.type == "CallExpression" &&
-          node.init.callee.name == "createLazyLoaders"
+          node.init.callee.name == "createLazyLoaders" &&
+          node.init.arguments.length >= 1
         ) {
           setPropertiesFromArgument(node.init, node.init.arguments[0]);
         }

tools/lint/eslint/eslint-plugin-mozilla/tests/balanced-observers.js

@@ -31,6 +31,10 @@ function error(code, observable) {
 
 ruleTester.run("balanced-observers", rule, {
   valid: [
+    "Services.obs.addObserver(observer);",
+    "Services.obs.removeObserver(observer);",
+    "Services.prefs.addObserver();",
+    "Services.prefs.removeObserver();",
     "Services.obs.addObserver(observer, 'observable');" +
       "Services.obs.removeObserver(observer, 'observable');",
     "Services.prefs.addObserver('preference.name', otherObserver);" +

tools/lint/eslint/eslint-plugin-mozilla/tests/no-addtask-setup.js

@@ -22,6 +22,7 @@ function callError() {
 
 ruleTester.run("no-addtask-setup", rule, {
   valid: [
+    "add_task();",
     "add_task(function() {});",
     "add_task(function () {});",
     "add_task(function foo() {});",

tools/lint/eslint/eslint-plugin-mozilla/tests/no-comparison-or-assignment-inside-ok.js

@@ -29,6 +29,7 @@ function invalidCode(code, output, messageId, data) {
 
 ruleTester.run("no-comparison-or-assignment-inside-ok", rule, {
   valid: [
+    "ok()",
     "ok(foo)",
     "ok(!bar)",
     "ok(!foo, 'Message')",