From bd3f092efa579944f75bfbc277b35f85e6d966ed Mon Sep 17 00:00:00 2001
From: cherryblossom000 <31467609+cherryblossom000@users.noreply.github.com>
Date: Sat, 23 May 2020 10:33:43 +1000
Subject: [PATCH] Fix: max-lines-per-function flagging arrow IIFEs (fixes
 #13332) (#13336)

---
 docs/rules/max-lines-per-function.md      |  8 +++++
 lib/rules/max-lines-per-function.js       |  2 +-
 tests/lib/rules/max-lines-per-function.js | 39 +++++++++++++++++++++++
 3 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/docs/rules/max-lines-per-function.md b/docs/rules/max-lines-per-function.md
index 22ffea79f41..d3b13615b42 100644
--- a/docs/rules/max-lines-per-function.md
+++ b/docs/rules/max-lines-per-function.md
@@ -165,6 +165,10 @@ Examples of **incorrect** code for this rule with the `{ "IIFEs": true }` option
 (function(){
     var x = 0;
 }());
+
+(() => {
+    var x = 0;
+})();
 ```
 
 Examples of **correct** code for this rule with the `{ "IIFEs": true }` option:
@@ -174,6 +178,10 @@ Examples of **correct** code for this rule with the `{ "IIFEs": true }` option:
 (function(){
     var x = 0;
 }());
+
+(() => {
+    var x = 0;
+})();
 ```
 
 ## When Not To Use It
diff --git a/lib/rules/max-lines-per-function.js b/lib/rules/max-lines-per-function.js
index 03539fae470..aa423a60a1f 100644
--- a/lib/rules/max-lines-per-function.js
+++ b/lib/rules/max-lines-per-function.js
@@ -134,7 +134,7 @@ module.exports = {
          * @returns {boolean} True if it's an IIFE
          */
         function isIIFE(node) {
-            return node.type === "FunctionExpression" && node.parent && node.parent.type === "CallExpression" && node.parent.callee === node;
+            return (node.type === "FunctionExpression" || node.type === "ArrowFunctionExpression") && node.parent && node.parent.type === "CallExpression" && node.parent.callee === node;
         }
 
         /**
diff --git a/tests/lib/rules/max-lines-per-function.js b/tests/lib/rules/max-lines-per-function.js
index 9107cd69f0f..008f2b01acb 100644
--- a/tests/lib/rules/max-lines-per-function.js
+++ b/tests/lib/rules/max-lines-per-function.js
@@ -164,6 +164,30 @@ if ( x === y ) {
     return bar;
 }());`,
             options: [{ max: 2, skipComments: true, skipBlankLines: false, IIFEs: false }]
+        },
+
+        // Arrow IIFEs should be recognised if IIFEs: true
+        {
+            code: `(() => {
+    let x = 0;
+    let y = 0;
+    let z = x + y;
+    let foo = {};
+    return bar;
+})();`,
+            options: [{ max: 7, skipComments: true, skipBlankLines: false, IIFEs: true }]
+        },
+
+        // Arrow IIFEs should not be recognised if IIFEs: false
+        {
+            code: `(() => {
+    let x = 0;
+    let y = 0;
+    let z = x + y;
+    let foo = {};
+    return bar;
+})();`,
+            options: [{ max: 2, skipComments: true, skipBlankLines: false, IIFEs: false }]
         }
     ],
 
@@ -435,6 +459,21 @@ if ( x === y ) {
             errors: [
                 { messageId: "exceed", data: { name: "Function", lineCount: 7, maxLines: 2 } }
             ]
+        },
+
+        // Test the IIFEs option includes arrow IIFEs
+        {
+            code: `(() => {
+    let x = 0;
+    let y = 0;
+    let z = x + y;
+    let foo = {};
+    return bar;
+})();`,
+            options: [{ max: 2, skipComments: true, skipBlankLines: false, IIFEs: true }],
+            errors: [
+                { messageId: "exceed", data: { name: "Arrow function", lineCount: 7, maxLines: 2 } }
+            ]
         }
     ]
 });