feat: Add onlyOneSimpleParam option to no-confusing-arrow rule

docs/rules/no-confusing-arrow.md

@@ -10,7 +10,9 @@ Here's an example where the usage of `=>` could be confusing:
 // The intent is not clear
 var x = a => 1 ? 2 : 3;
 // Did the author mean this
-var x = function (a) { return 1 ? 2 : 3 };
+var x = function (a) {
+    return 1 ? 2 : 3;
+};
 // Or this
 var x = a <= 1 ? 2 : 3;
 ```
@@ -25,28 +27,32 @@ Examples of **incorrect** code for this rule:
 
 var x = a => 1 ? 2 : 3;
 var x = (a) => 1 ? 2 : 3;
+var x = a => { return 1 ? 2 : 3; };
 ```
 
 Examples of **correct** code for this rule:
 
 ```js
 /*eslint no-confusing-arrow: "error"*/
 /*eslint-env es6*/
-
 var x = a => (1 ? 2 : 3);
 var x = (a) => (1 ? 2 : 3);
-var x = a => { return 1 ? 2 : 3; };
-var x = (a) => { return 1 ? 2 : 3; };
+var x = (a) => {
+    return 1 ? 2 : 3;
+};
 ```
 
 ## Options
 
-This rule accepts a single options argument with the following defaults:
+This rule accepts two options argument with the following defaults:
 
 ```json
 {
     "rules": {
-        "no-confusing-arrow": ["error", {"allowParens": true}]
+        "no-confusing-arrow": [
+            "error",
+            { "allowParens": true, "onlyOneSimpleParam": false }
+        ]
     }
 }
 ```
@@ -65,6 +71,24 @@ var x = a => (1 ? 2 : 3);
 var x = (a) => (1 ? 2 : 3);
 ```
 
+`onlyOneSimpleParam` is a boolean setting that can be `true` or `false`(default):
+
+1. `true` relaxes the rule and doesn't report errors if the arrow function has 0 or more than 1 parameters, or the parameter is not an identifier.
+2. `false` warns regardless of parameters.
+
+Examples of **correct** code for this rule with the `{"onlyOneSimpleParam": true}` option:
+
+```js
+/*eslint no-confusing-arrow: ["error", {"onlyOneSimpleParam": true}]*/
+/*eslint-env es6*/
+() => 1 ? 2 : 3;
+(a, b) => 1 ? 2 : 3;
+(a = b) => 1 ? 2 : 3;
+({ a }) => 1 ? 2 : 3;
+([a]) => 1 ? 2 : 3;
+(...a) => 1 ? 2 : 3;
+```
+
 ## Related Rules
 
 * [no-constant-condition](no-constant-condition.md)

lib/rules/no-confusing-arrow.js

@@ -41,7 +41,8 @@ module.exports = {
         schema: [{
             type: "object",
             properties: {
-                allowParens: { type: "boolean", default: true }
+                allowParens: { type: "boolean", default: true },
+                onlyOneSimpleParam: { type: "boolean", default: false }
             },
             additionalProperties: false
         }],
@@ -54,6 +55,7 @@ module.exports = {
     create(context) {
         const config = context.options[0] || {};
         const allowParens = config.allowParens || (config.allowParens === void 0);
+        const onlyOneSimpleParam = config.onlyOneSimpleParam;
         const sourceCode = context.getSourceCode();
 
 
@@ -65,7 +67,9 @@ module.exports = {
         function checkArrowFunc(node) {
             const body = node.body;
 
-            if (isConditional(body) && !(allowParens && astUtils.isParenthesised(sourceCode, body))) {
+            if (isConditional(body) &&
+                !(allowParens && astUtils.isParenthesised(sourceCode, body)) &&
+                !(onlyOneSimpleParam && !(node.params.length === 1 && node.params[0].type === "Identifier"))) {
                 context.report({
                     node,
                     messageId: "confusing",

tests/lib/rules/no-confusing-arrow.js

@@ -30,7 +30,15 @@ ruleTester.run("no-confusing-arrow", rule, {
         { code: "var x = (a) => { return 1 ? 2 : 3; }", options: [{ allowParens: false }] },
 
         "var x = a => (1 ? 2 : 3)",
-        { code: "var x = a => (1 ? 2 : 3)", options: [{ allowParens: true }] }
+        { code: "var x = a => (1 ? 2 : 3)", options: [{ allowParens: true }] },
+
+        "var x = (a,b) => (1 ? 2 : 3)",
+        { code: "() => 1 ? 2 : 3", options: [{ onlyOneSimpleParam: true }] },
+        { code: "(a, b) => 1 ? 2 : 3", options: [{ onlyOneSimpleParam: true }] },
+        { code: "(a = b) => 1 ? 2 : 3", options: [{ onlyOneSimpleParam: true }] },
+        { code: "({ a }) => 1 ? 2 : 3", options: [{ onlyOneSimpleParam: true }] },
+        { code: "([a]) => 1 ? 2 : 3", options: [{ onlyOneSimpleParam: true }] },
+        { code: "(...a) => 1 ? 2 : 3", options: [{ onlyOneSimpleParam: true }] }
     ],
     invalid: [
         {
@@ -71,6 +79,48 @@ ruleTester.run("no-confusing-arrow", rule, {
             code: "var x = (a) => 1 ? 2 : 3",
             output: "var x = (a) => (1 ? 2 : 3)",
             errors: [{ messageId: "confusing" }]
+        },
+        {
+            code: "var x = () => 1 ? 2 : 3",
+            output: "var x = () => (1 ? 2 : 3)",
+            errors: [{ messageId: "confusing" }]
+        },
+        {
+            code: "var x = () => 1 ? 2 : 3",
+            output: "var x = () => (1 ? 2 : 3)",
+            options: [{}],
+            errors: [{ messageId: "confusing" }]
+        },
+        {
+            code: "var x = () => 1 ? 2 : 3",
+            output: "var x = () => (1 ? 2 : 3)",
+            options: [{ onlyOneSimpleParam: false }],
+            errors: [{ messageId: "confusing" }]
+        },
+        {
+            code: "var x = (a, b) => 1 ? 2 : 3",
+            output: "var x = (a, b) => (1 ? 2 : 3)",
+            errors: [{ messageId: "confusing" }]
+        },
+        {
+            code: "var x = (a = b) => 1 ? 2 : 3",
+            output: "var x = (a = b) => (1 ? 2 : 3)",
+            errors: [{ messageId: "confusing" }]
+        },
+        {
+            code: "var x = ({ a }) => 1 ? 2 : 3",
+            output: "var x = ({ a }) => (1 ? 2 : 3)",
+            errors: [{ messageId: "confusing" }]
+        },
+        {
+            code: "var x = ([a]) => 1 ? 2 : 3",
+            output: "var x = ([a]) => (1 ? 2 : 3)",
+            errors: [{ messageId: "confusing" }]
+        },
+        {
+            code: "var x = (...a) => 1 ? 2 : 3",
+            output: "var x = (...a) => (1 ? 2 : 3)",
+            errors: [{ messageId: "confusing" }]
         }
     ]
 });