Update: shebang gets fixable (fixes #8)

README.md

@@ -38,4 +38,4 @@ Some rules are slow because it searches `package.json` and opens it.
 - [no-missing-import](docs/rules/no-missing-import.md) - Disallow invalid `import` and `export` declarations.
 - [no-missing-require](docs/rules/no-missing-require.md) - Disallow invalid `require()`s.
 - [no-unsupported-features](docs/rules/no-unsupported-features.md) - Disallow unsupported ECMAScript features on the specified version.
-- [shebang](docs/rules/shebang.md) - Suggest correct usage of shebang.
+- [shebang](docs/rules/shebang.md) - Suggest correct usage of shebang. (fixable)

docs/rules/shebang.md

@@ -3,6 +3,8 @@
 When we make a CLI tool on Node.js, we add `bin` field to `package.json`, then we add a shebang the entry file.
 This rule suggests correct usage of shebang.
 
+**Fixable:** This rule is automatically fixable using the `--fix` flag on the command line.
+
 ## Rule Details
 
 This rule looks up `package.json` file from each linitng target file.

lib/rules/shebang.js

@@ -17,6 +17,9 @@ var getPackageJson = require("../util/get-package-json");
 // Helpers
 //------------------------------------------------------------------------------
 
+var NODE_SHEBANG = "#!/usr/bin/env node\n";
+var SHEBANG_PATTERN = /^#\!.+?\n/;
+
 /**
  * Checks whether or not a given path is a `bin` file.
  *
@@ -41,13 +44,14 @@ function isBinFile(filePath, convert) {
 }
 
 /**
- * Checks whether or not a given code has the valid shebang for Node.js.
+ * Gets the shebang line (includes a line ending) from a given code.
  *
  * @param {SourceCode} sourceCode - A source code object to check.
- * @returns {boolean} `true` if the source code has the valid shebang.
+ * @returns {string} shebang if exists. Otherwise an empty string.
  */
-function hasShebang(sourceCode) {
-    return /^#\!\/usr\/bin\/env node\n/.test(sourceCode.text);
+function getShebang(sourceCode) {
+    var m = SHEBANG_PATTERN.exec(sourceCode.text);
+    return (m && m[0]) || "";
 }
 
 //------------------------------------------------------------------------------
@@ -82,20 +86,30 @@ module.exports = function(context) {
             }
 
             var needsShebang = isBinFile(filePath, convertBinPath);
-            var shebang = hasShebang(sourceCode);
-            if (needsShebang === shebang) {
+            var shebang = getShebang(sourceCode);
+            if (needsShebang ? shebang === NODE_SHEBANG : !shebang) {
                 return;
             }
 
             if (needsShebang) {
                 context.report({
                     node: node,
-                    message: "This file needs shebang \"#!/usr/bin/env node\"."
+                    message: "This file needs shebang \"#!/usr/bin/env node\".",
+                    fix: function(fixer) {
+                        if (shebang) {
+                            return fixer.replaceTextRange([0, shebang.length], NODE_SHEBANG);
+                        } else {
+                            return fixer.insertTextBefore(node, NODE_SHEBANG);
+                        }
+                    }
                 });
             } else {
                 context.report({
                     node: node,
-                    message: "This file needs no shebang."
+                    message: "This file needs no shebang.",
+                    fix: function(fixer) {
+                        return fixer.removeRange([0, shebang.length]);
+                    }
                 });
             }
         }

tests/lib/rules/shebang.js

@@ -108,79 +108,93 @@ ruleTester.run("shebang", rule, {
         {
             filename: fixture("string-bin/bin/test.js"),
             code: "hello();",
+            output: "#!/usr/bin/env node\nhello();",
             errors: ["This file needs shebang \"#!/usr/bin/env node\"."]
         },
         {
             filename: fixture("string-bin/bin/test.js"),
             code: "#!/usr/bin/node\nhello();",
+            output: "#!/usr/bin/env node\nhello();",
             errors: ["This file needs shebang \"#!/usr/bin/env node\"."]
         },
         {
             filename: fixture("string-bin/lib/test.js"),
             code: "#!/usr/bin/env node\nhello();",
+            output: "hello();",
             errors: ["This file needs no shebang."]
         },
         {
             filename: fixture("object-bin/bin/a.js"),
             code: "hello();",
+            output: "#!/usr/bin/env node\nhello();",
             errors: ["This file needs shebang \"#!/usr/bin/env node\"."]
         },
         {
             filename: fixture("object-bin/bin/b.js"),
             code: "#!/usr/bin/node\nhello();",
+            output: "#!/usr/bin/env node\nhello();",
             errors: ["This file needs shebang \"#!/usr/bin/env node\"."]
         },
         {
             filename: fixture("object-bin/bin/c.js"),
             code: "#!/usr/bin/env node\nhello();",
+            output: "hello();",
             errors: ["This file needs no shebang."]
         },
         {
             filename: fixture("no-bin-field/lib/test.js"),
             code: "#!/usr/bin/env node\nhello();",
+            output: "hello();",
             errors: ["This file needs no shebang."]
         },
 
         // convertBinPath
         {
             filename: fixture("string-bin/src/bin/test.js"),
             code: "hello();",
+            output: "#!/usr/bin/env node\nhello();",
             options: [{"convertBinPath": ["bin", "src/bin"]}],
             errors: ["This file needs shebang \"#!/usr/bin/env node\"."]
         },
         {
             filename: fixture("string-bin/src/bin/test.js"),
             code: "#!/usr/bin/node\nhello();",
+            output: "#!/usr/bin/env node\nhello();",
             options: [{"convertBinPath": ["bin", "src/bin"]}],
             errors: ["This file needs shebang \"#!/usr/bin/env node\"."]
         },
         {
             filename: fixture("string-bin/src/lib/test.js"),
             code: "#!/usr/bin/env node\nhello();",
+            output: "hello();",
             options: [{"convertBinPath": ["bin", "src/bin"]}],
             errors: ["This file needs no shebang."]
         },
         {
             filename: fixture("object-bin/src/bin/a.js"),
             code: "hello();",
+            output: "#!/usr/bin/env node\nhello();",
             options: [{"convertBinPath": ["bin", "src/bin"]}],
             errors: ["This file needs shebang \"#!/usr/bin/env node\"."]
         },
         {
             filename: fixture("object-bin/src/bin/b.js"),
             code: "#!/usr/bin/node\nhello();",
+            output: "#!/usr/bin/env node\nhello();",
             options: [{"convertBinPath": ["bin", "src/bin"]}],
             errors: ["This file needs shebang \"#!/usr/bin/env node\"."]
         },
         {
             filename: fixture("object-bin/src/bin/c.js"),
             code: "#!/usr/bin/env node\nhello();",
+            output: "hello();",
             options: [{"convertBinPath": ["bin", "src/bin"]}],
             errors: ["This file needs no shebang."]
         },
         {
             filename: fixture("no-bin-field/src/lib/test.js"),
             code: "#!/usr/bin/env node\nhello();",
+            output: "hello();",
             options: [{"convertBinPath": ["bin", "src/bin"]}],
             errors: ["This file needs no shebang."]
         }