fix: lines-around-comment apply allowBlockStart for switch statements (#16153)

* fix: apply `allowBlockStart` for switch statements too

* docs: add switch statement examples for lines-around-comment-rule

* fix: check if comment is after the `{` token

* fix: check for the correct opening brace

* docs: add switch statements for allowBlockEnd and allowBlockStart (lines-around-comment)

Author: snitin315

docs/src/rules/lines-around-comment.md

@@ -25,8 +25,8 @@ This rule has an object option:
 * `"afterBlockComment": true` requires an empty line after block comments
 * `"beforeLineComment": true` requires an empty line before line comments
 * `"afterLineComment": true` requires an empty line after line comments
-* `"allowBlockStart": true` allows comments to appear at the start of block statements, function bodies, classes, and class static blocks
-* `"allowBlockEnd": true` allows comments to appear at the end of block statements, function bodies, classes, and class static blocks
+* `"allowBlockStart": true` allows comments to appear at the start of block statements, function bodies, classes, switch statements, and class static blocks
+* `"allowBlockEnd": true` allows comments to appear at the end of block statements, function bodies, classes, switch statements, and class static blocks
 * `"allowObjectStart": true` allows comments to appear at the start of object literals
 * `"allowObjectEnd": true` allows comments to appear at the end of object literals
 * `"allowArrayStart": true` allows comments to appear at the start of array literals
@@ -230,6 +230,14 @@ class C {
         foo();
     }
 }
+
+switch (foo) {
+  /* what a great and wonderful day */
+
+  case 1:    
+    bar();
+    break;
+}
 ```
 
 :::
@@ -308,6 +316,14 @@ class C {
 
     /* what a great and wonderful day */
 }
+
+switch (foo) {
+  case 1:    
+    bar();
+    break;
+
+  /* what a great and wonderful day */
+}
 ```
 
 :::

lib/rules/lines-around-comment.js

@@ -231,9 +231,15 @@ module.exports = {
             const parent = getParentNodeOfToken(token);
 
             if (parent && isParentNodeType(parent, nodeType)) {
-                const parentStartNodeOrToken = parent.type === "StaticBlock"
-                    ? sourceCode.getFirstToken(parent, { skip: 1 }) // opening brace of the static block
-                    : parent;
+                let parentStartNodeOrToken = parent;
+
+                if (parent.type === "StaticBlock") {
+                    parentStartNodeOrToken = sourceCode.getFirstToken(parent, { skip: 1 }); // opening brace of the static block
+                } else if (parent.type === "SwitchStatement") {
+                    parentStartNodeOrToken = sourceCode.getTokenAfter(parent.discriminant, {
+                        filter: astUtils.isOpeningBraceToken
+                    }); // opening brace of the switch statement
+                }
 
                 return token.loc.start.line - parentStartNodeOrToken.loc.start.line === 1;
             }
@@ -264,7 +270,8 @@ module.exports = {
                 isCommentAtParentStart(token, "ClassBody") ||
                 isCommentAtParentStart(token, "BlockStatement") ||
                 isCommentAtParentStart(token, "StaticBlock") ||
-                isCommentAtParentStart(token, "SwitchCase")
+                isCommentAtParentStart(token, "SwitchCase") ||
+                isCommentAtParentStart(token, "SwitchStatement")
             );
         }
 

tests/lib/rules/lines-around-comment.js

@@ -364,6 +364,60 @@ ruleTester.run("lines-around-comment", rule, {
             parserOptions: { ecmaVersion: 2022 }
         },
 
+        // https://github.com/eslint/eslint/issues/16131
+        {
+            code: `
+            switch (foo) {
+            // this comment is allowed by allowBlockStart: true 
+                
+            case 1:    
+                bar();
+                break;
+                
+            // this comment is allowed by allowBlockEnd: true
+            }
+            `,
+            options: [{
+                allowBlockStart: true,
+                beforeLineComment: true,
+                afterLineComment: true,
+                allowBlockEnd: true
+            }]
+        },
+        {
+            code: `
+            switch (foo)
+            {
+            // this comment is allowed by allowBlockStart: true 
+                
+            case 1:    
+                bar();
+                break;
+            }
+            `,
+            options: [{
+                allowBlockStart: true,
+                beforeLineComment: true,
+                afterLineComment: true
+            }]
+        },
+        {
+            code: `
+            switch (
+                function(){}()
+            )
+            {
+                // this comment is allowed by allowBlockStart: true
+                case foo:
+                    break;
+            }
+            `,
+            options: [{
+                allowBlockStart: true,
+                beforeLineComment: true
+            }]
+        },
+
         // check for block end comments
         {
             code: "var a,\n// line\n\nb;",
@@ -2106,6 +2160,39 @@ ruleTester.run("lines-around-comment", rule, {
             output: "foo;\n\n/* fallthrough */",
             options: [],
             errors: [{ messageId: "before", type: "Block" }]
+        },
+        {
+            code: `
+            switch (
+            // this comment is not allowed by allowBlockStart: true
+
+                foo
+            )
+            {   
+            case 1:    
+                bar();
+                break;
+            }
+            `,
+            output: `
+            switch (
+
+            // this comment is not allowed by allowBlockStart: true
+
+                foo
+            )
+            {   
+            case 1:    
+                bar();
+                break;
+            }
+            `,
+            options: [{
+                allowBlockStart: true,
+                beforeLineComment: true,
+                afterLineComment: true
+            }],
+            errors: [{ messageId: "before", type: "Line" }]
         }
     ]