style: Add new ESLint rule no-empty-string-for-ifbreak (#10172)

* Add new ESLint rule for ifBreak

* Fix for third argument

* Run fix with new rule

* Address review

* Fix

* Update no-empty-flat-contents-for-if-break.js

* Fix CI config

Co-authored-by: fisker Cheung <lionkay@gmail.com>

.eslintrc.yml

@@ -117,6 +117,7 @@ overrides:
       prettier-internal-rules/no-doc-builder-concat: error
       prettier-internal-rules/prefer-fast-path-each: error
       prettier-internal-rules/prefer-is-non-empty-array: error
+      prettier-internal-rules/no-empty-flat-contents-for-if-break: error
   - files: src/document/*.js
     rules:
       prettier-internal-rules/no-doc-builder-concat: off

.github/workflows/eslint-rules.yml

@@ -3,11 +3,11 @@ name: Internal_ESLint_Rules_Test
 on:
   push:
     paths:
-      - "scripts/tools/eslint-plugin-prettier-internal-rules"
+      - "scripts/tools/eslint-plugin-prettier-internal-rules/**"
       - ".github/workflows/eslint-rules.yml"
   pull_request:
     paths:
-      - "scripts/tools/eslint-plugin-prettier-internal-rules"
+      - "scripts/tools/eslint-plugin-prettier-internal-rules/**"
       - ".github/workflows/eslint-rules.yml"
 
 jobs:

scripts/tools/eslint-plugin-prettier-internal-rules/index.js

@@ -10,5 +10,6 @@ module.exports = {
     "prefer-fast-path-each": require("./prefer-fast-path-each"),
     "prefer-is-non-empty-array": require("./prefer-is-non-empty-array"),
     "require-json-extensions": require("./require-json-extensions"),
+    "no-empty-flat-contents-for-if-break": require("./no-empty-flat-contents-for-if-break"),
   },
 };

scripts/tools/eslint-plugin-prettier-internal-rules/no-empty-flat-contents-for-if-break.js

@@ -0,0 +1,42 @@
+"use strict";
+
+const selector = [
+  "CallExpression",
+  "[optional=false]",
+  '[callee.type="Identifier"]',
+  '[callee.name="ifBreak"]',
+  "[arguments.length=2]",
+  '[arguments.1.type="Literal"]',
+  '[arguments.1.value=""]',
+  ':not([arguments.0.type="SpreadElement"])',
+].join("");
+
+const messageId = "no-empty-flat-contents-for-if-break";
+
+module.exports = {
+  meta: {
+    type: "suggestion",
+    docs: {
+      url:
+        "https://github.com/prettier/prettier/blob/main/scripts/eslint-plugin-prettier-internal-rules/no-empty-flat-contents-for-if-break.js",
+    },
+    messages: {
+      [messageId]:
+        "Please don't pass an empty string to second parameter of ifBreak.",
+    },
+    fixable: "code",
+  },
+  create(context) {
+    return {
+      [selector](node) {
+        const [breakContents] = node.arguments;
+        context.report({
+          node,
+          messageId,
+          fix: (fixer) =>
+            fixer.removeRange([breakContents.range[1], node.range[1] - 1]),
+        });
+      },
+    };
+  },
+};

scripts/tools/eslint-plugin-prettier-internal-rules/test.js

@@ -204,3 +204,46 @@ test("require-json-extensions", {
     },
   ],
 });
+
+test("no-empty-flat-contents-for-if-break", {
+  valid: [
+    "ifBreak('foo', 'bar')",
+    "ifBreak(doc1, doc2)",
+    "ifBreak(',')",
+    "ifBreak(doc)",
+    "ifBreak('foo', '', { groupId })",
+    "ifBreak(...foo, { groupId })",
+  ],
+  invalid: [
+    {
+      code: "ifBreak('foo', '')",
+      output: "ifBreak('foo')",
+      errors: [
+        {
+          message:
+            "Please don't pass an empty string to second parameter of ifBreak.",
+        },
+      ],
+    },
+    {
+      code: "ifBreak('foo'    ,     ''   )",
+      output: "ifBreak('foo')",
+      errors: [
+        {
+          message:
+            "Please don't pass an empty string to second parameter of ifBreak.",
+        },
+      ],
+    },
+    {
+      code: "ifBreak(doc, '')",
+      output: "ifBreak(doc)",
+      errors: [
+        {
+          message:
+            "Please don't pass an empty string to second parameter of ifBreak.",
+        },
+      ],
+    },
+  ],
+});

src/language-css/printer-postcss.js

@@ -186,7 +186,7 @@ function genericPrint(path, options, print) {
             options.originalText[locEnd(node) - 1] !== ";"
           ? ""
           : options.__isHTMLStyleAttribute && isLastNode(path, node)
-          ? ifBreak(";", "")
+          ? ifBreak(";")
           : ";",
       ];
     }

src/language-js/print/ternary.js

@@ -221,10 +221,10 @@ function printTernary(path, options, print) {
     // parens when using ?: within JSX, because the parens are analogous to
     // curly braces in an if statement.
     const wrap = (doc) => [
-      ifBreak("(", ""),
+      ifBreak("("),
       indent([softline, doc]),
       softline,
-      ifBreak(")", ""),
+      ifBreak(")"),
     ];
 
     // The only things we don't wrap are:

src/language-js/print/typescript.js

@@ -348,7 +348,7 @@ function printTypescript(path, options, print) {
             n.optional ? getTypeScriptMappedTypeModifier(n.optional, "?") : "",
             n.typeAnnotation ? ": " : "",
             path.call(print, "typeAnnotation"),
-            ifBreak(semi, ""),
+            ifBreak(semi),
           ]),
           printDanglingComments(path, options, /* sameIndent */ true),
           options.bracketSpacing ? line : softline,

src/language-yaml/print/flow-mapping-sequence.js

@@ -29,7 +29,7 @@ function printFlowMapping(path, print, options) {
     alignWithSpaces(options.tabWidth, [
       bracketSpacing,
       printChildren(path, print, options),
-      options.trailingComma === "none" ? "" : ifBreak(",", ""),
+      options.trailingComma === "none" ? "" : ifBreak(","),
       hasEndComments(node)
         ? [hardline, join(hardline, path.map(print, "endComments"))]
         : "",