From 428cabc4bf2d5e75b1f7dcd530fec719c33049fc Mon Sep 17 00:00:00 2001
From: Kai Cataldo <kaicataldo@gmail.com>
Date: Thu, 26 Sep 2019 03:52:06 -0400
Subject: [PATCH] Fix: preserve whitespace in multiline-comment-style (fixes
 #12312)

---
 lib/rules/multiline-comment-style.js       |  17 ++-
 tests/lib/rules/multiline-comment-style.js | 136 ++++++++++++++++++++-
 2 files changed, 146 insertions(+), 7 deletions(-)

diff --git a/lib/rules/multiline-comment-style.js b/lib/rules/multiline-comment-style.js
index 6578a120126b..dd5826976217 100644
--- a/lib/rules/multiline-comment-style.js
+++ b/lib/rules/multiline-comment-style.js
@@ -142,7 +142,8 @@ module.exports = {
                 } else {
                     const block = commentGroup[0];
                     const lines = block.value.split(astUtils.LINEBREAK_MATCHER);
-                    const expectedLinePrefix = `${sourceCode.text.slice(block.range[0] - block.loc.start.column, block.range[0])} *`;
+                    const expectedLeadingWhitespace = sourceCode.text.slice(block.range[0] - block.loc.start.column, block.range[0]);
+                    const expectedLinePrefix = `${expectedLeadingWhitespace} *`;
 
                     if (!/^\*?\s*$/u.test(lines[0])) {
                         const start = block.value.startsWith("*") ? block.range[0] + 1 : block.range[0];
@@ -182,12 +183,16 @@ module.exports = {
                                     : "missingStar",
                                 fix(fixer) {
                                     const lineStartIndex = sourceCode.getIndexFromLoc({ line: lineNumber, column: 0 });
-                                    const linePrefixLength = lineText.match(/^\s*\*? ?/u)[0].length;
-                                    const commentStartIndex = lineStartIndex + linePrefixLength;
-
-                                    const replacementText = lineNumber === block.loc.end.line || lineText.length === linePrefixLength
+                                    const [linePrefix, whitespaceBefore, whitespaceAfter] = lineText.match(/^(\s*)\*?(\s*)/u);
+                                    const commentStartIndex = lineStartIndex + linePrefix.length;
+                                    const leadingWhitespace = whitespaceAfter || ` ${
+                                        whitespaceBefore.startsWith(expectedLeadingWhitespace)
+                                            ? whitespaceBefore.replace(expectedLeadingWhitespace, "")
+                                            : ""
+                                    }`;
+                                    const replacementText = lineNumber === block.loc.end.line || lineText.length === linePrefix.length
                                         ? expectedLinePrefix
-                                        : `${expectedLinePrefix} `;
+                                        : `${expectedLinePrefix}${leadingWhitespace}`;
 
                                     return fixer.replaceTextRange([lineStartIndex, commentStartIndex], replacementText);
                                 }
diff --git a/tests/lib/rules/multiline-comment-style.js b/tests/lib/rules/multiline-comment-style.js
index 58c13581d4dc..6d4216a75f81 100644
--- a/tests/lib/rules/multiline-comment-style.js
+++ b/tests/lib/rules/multiline-comment-style.js
@@ -322,7 +322,7 @@ ruleTester.run("multiline-comment-style", rule, {
             code: `
                 /*
                  * the following line
-                 is missing a '*' at the start
+                is missing a '*' at the start
                  */
             `,
             output: `
@@ -333,6 +333,21 @@ ruleTester.run("multiline-comment-style", rule, {
             `,
             errors: [{ messageId: "missingStar", line: 4 }]
         },
+        {
+            code: `
+                /*
+                 * the following line
+                 is missing a '*' at the start
+                 */
+            `,
+            output: `
+                /*
+                 * the following line
+                 *  is missing a '*' at the start
+                 */
+            `,
+            errors: [{ messageId: "missingStar", line: 4 }]
+        },
         {
             code: `
                 /*
@@ -482,6 +497,125 @@ ruleTester.run("multiline-comment-style", rule, {
             `,
             options: ["bare-block"],
             errors: [{ messageId: "expectedBareBlock", line: 2 }]
+        },
+        {
+            code: `
+                /*
+                {
+                    "foo": 1,
+                    "bar": 2
+                }
+                */
+            `,
+            output: `
+                /*
+                 * {
+                 *     "foo": 1,
+                 *     "bar": 2
+                 * }
+                 */
+            `,
+            errors: [
+                { messageId: "missingStar", line: 3 },
+                { messageId: "missingStar", line: 4 },
+                { messageId: "missingStar", line: 5 },
+                { messageId: "missingStar", line: 6 },
+                { messageId: "alignment", line: 7 }
+            ]
+        },
+        {
+            code: `
+                /*
+                {
+                \t"foo": 1,
+                \t"bar": 2
+                }
+                */
+            `,
+            output: `
+                /*
+                 * {
+                 * \t"foo": 1,
+                 * \t"bar": 2
+                 * }
+                 */
+            `,
+            errors: [
+                { messageId: "missingStar", line: 3 },
+                { messageId: "missingStar", line: 4 },
+                { messageId: "missingStar", line: 5 },
+                { messageId: "missingStar", line: 6 },
+                { messageId: "alignment", line: 7 }
+            ]
+        },
+        {
+            code: `
+                /*
+                {
+                \t  "foo": 1,
+                \t  "bar": 2
+                }
+                */
+            `,
+            output: `
+                /*
+                 * {
+                 * \t  "foo": 1,
+                 * \t  "bar": 2
+                 * }
+                 */
+            `,
+            errors: [
+                { messageId: "missingStar", line: 3 },
+                { messageId: "missingStar", line: 4 },
+                { messageId: "missingStar", line: 5 },
+                { messageId: "missingStar", line: 6 },
+                { messageId: "alignment", line: 7 }
+            ]
+        },
+        {
+            code: `
+                /*
+                {
+               \t"foo": 1,
+               \t"bar": 2
+                }
+                */
+            `,
+            output: `
+                /*
+                 * {
+                 * "foo": 1,
+                 * "bar": 2
+                 * }
+                 */
+            `,
+            errors: [
+                { messageId: "missingStar", line: 3 },
+                { messageId: "missingStar", line: 4 },
+                { messageId: "missingStar", line: 5 },
+                { messageId: "missingStar", line: 6 },
+                { messageId: "alignment", line: 7 }
+            ]
+        },
+        {
+            code: `
+                //{
+                //    "foo": 1,
+                //    "bar": 2
+                //}
+            `,
+            output: `
+                /*
+                 *{
+                 *    "foo": 1,
+                 *    "bar": 2
+                 *}
+                 */
+            `,
+            errors: [
+                { messageId: "expectedBlock", line: 2 }
+            ]
         }
     ]
 });