Accepts piped input from stdin

Fixes jscs-dev#448
Closes jscs-devgh-505

README.md

@@ -43,6 +43,12 @@ To run `jscs`, you can use the following command from the project root:
 jscs path[ path[...]]
 ```
 
+You can also pipe input into jscs:
+
+```
+cat myfile.js | jscs
+```
+
 ## CLI
 
 ### `--config`

bin/jscs

@@ -1,5 +1,7 @@
 #!/usr/bin/env node
 var cli = require('../lib/cli');
+var stdin = process.stdin;
+var _stdInput = [];
 
 /**
  * Command line implementation for JSCS.
@@ -26,4 +28,19 @@ program
     .option('', '\t  /path/to/my-reporter\t\t(absolute path without extension)')
     .parse(process.argv);
 
-cli(program);
+if (process.argv.length === 2) {
+    // Handle usage like cat myfile.js | jscs
+    stdin.setEncoding('utf8');
+
+    stdin.on('data', function(chunk) {
+        _stdInput.push(chunk);
+    });
+
+    stdin.on('end', function() {
+        program._stdin = _stdInput.join();
+        cli(program);
+    });
+
+} else {
+    cli(program);
+}

lib/cli.js

@@ -63,7 +63,7 @@ module.exports = function(program) {
         return returnArgs;
     }
 
-    if (args.length === 0) {
+    if (args.length === 0 && !program._stdin) {
         console.error('No input files specified. Try option --help for usage information.');
         defer.reject(1);
 
@@ -105,25 +105,38 @@ module.exports = function(program) {
     checker.registerDefaultRules();
     checker.configure(config);
 
-    /**
-     * Processing specified files and dirs.
-     */
-    Vow.all(args.map(checker.checkPath, checker)).then(function(results) {
-        var errorsCollection = [].concat.apply([], results);
-
-        reporter(errorsCollection);
+    if (typeof program._stdin !== 'undefined') {
+        var errors = checker.checkString(program._stdin);
+        reporter([errors]);
 
-        errorsCollection.forEach(function(errors) {
-            if (!errors.isEmpty()) {
-                defer.reject(2);
-            }
-        });
+        if (!errors.isEmpty()) {
+            defer.reject(2);
+        }
 
         defer.resolve(0);
-    }).fail(function(e) {
-        console.error(e.stack);
-        defer.reject(1);
-    });
+    }
+
+    if (args.length) {
+        /**
+         * Processing specified files and dirs.
+         */
+        Vow.all(args.map(checker.checkPath, checker)).then(function(results) {
+            var errorsCollection = [].concat.apply([], results);
+
+            reporter(errorsCollection);
+
+            errorsCollection.forEach(function(errors) {
+                if (!errors.isEmpty()) {
+                    defer.reject(2);
+                }
+            });
+
+            defer.resolve(0);
+        }).fail(function(e) {
+            console.error(e.stack);
+            defer.reject(1);
+        });
+    }
 
     return returnArgs;
 };

test/cli.js

@@ -7,6 +7,8 @@ var hasAnsi = require('has-ansi');
 
 var path = require('path');
 
+var exec = require('child_process').exec;
+
 var cli = require('../lib/cli');
 var startingDir = process.cwd();
 
@@ -162,6 +164,46 @@ describe('modules/cli', function() {
         });
     });
 
+    describe('input via stdin (#448)', function() {
+        var bin = path.resolve(__dirname, '../bin/jscs');
+
+        it('should accept cat\'d file input via stdin', function (done) {
+            rAfter();
+
+            var testFile = __dirname + '/data/cli/stdin.js';
+            var cmd = 'cat ' + testFile + ' | ' + bin;
+
+            exec(cmd, function (error, stdout) {
+                assert(!error);
+                done();
+            });
+        });
+
+        it('should accept echo\'d input via stdin', function (done) {
+            rAfter();
+
+            var cmd = 'echo "var x = [1, 2];" | ' + bin;
+
+            exec(cmd, function (error, stdout) {
+                assert(!error);
+                done();
+            });
+        });
+
+        it('should still bail for empty input being piped', function(done) {
+            // 'cat myEmptyFile.js | jscs' should report a successful run
+            rAfter();
+
+            var testFile = __dirname + '/data/cli/success.js';
+            var cmd = 'cat ' + testFile + ' | ' + bin;
+
+            exec(cmd, function (error) {
+                assert(error.code);
+                done();
+            });
+        });
+    });
+
     describe('reporter option', function() {
         it('should set implicitly set checkstyle reporter', function() {
             var result = cli({

test/data/cli/stdin.js

@@ -0,0 +1 @@
+var x = {a: 'a'};