Add more json validation rules

src/Composer/Json/JsonFile.php

@@ -19,6 +19,7 @@ use Composer\Composer;
  * Reads/writes json files.
  *
  * @author Konstantin Kudryashiv <ever.zet@gmail.com>
+ * @author Jordi Boggiano <j.boggiano@seld.be>
  */
 class JsonFile
 {
@@ -120,17 +121,29 @@ class JsonFile
                 break;
             case JSON_ERROR_SYNTAX:
                 $msg = 'Syntax error';
+                $charOffset = 0;
                 if (preg_match('#["}\]]\s*(,)\s*\}#', $json, $match, PREG_OFFSET_CAPTURE)) {
-                    $msg .= ', extra comma on line '.(substr_count(substr($json, 0, $match[1][1]), "\n")+1);
+                    $msg .= ', extra comma';
+                } elseif (preg_match('#(["}\]]) *\r?\n *"#', $json, $match, PREG_OFFSET_CAPTURE)) {
+                    $msg .= ', missing comma';
+                    $charOffset = 1;
+                } elseif (preg_match('#^ *([a-z0-9_-]+) *:#mi', $json, $match, PREG_OFFSET_CAPTURE)) {
+                    $msg .= ', you must use double quotes (") around keys';
                 } elseif (preg_match('#(\'.+?\' *:|: *\'.+?\')#', $json, $match, PREG_OFFSET_CAPTURE)) {
-                    $msg .= ', use double quotes (") instead of single quotes (\') on line '.(substr_count(substr($json, 0, $match[1][1]), "\n")+1);
+                    $msg .= ', use double quotes (") instead of single quotes (\')';
+                } elseif (preg_match('#(\[".*?":.*?\])#', $json, $match, PREG_OFFSET_CAPTURE)) {
+                    $msg .= ', you must use the hash syntax (e.g. {"foo": "bar"}) instead of array syntax (e.g. ["foo", "bar"])';
+                }
+                if (isset($match[1][1])) {
+                    $preError = substr($json, 0, $match[1][1]);
+                    $msg .= ' on line '.(substr_count($preError, "\n")+1).', char '.abs(strrpos($preError, "\n") - strlen($preError) - $charOffset);
                 }
                 break;
             case JSON_ERROR_UTF8:
                 $msg = 'Malformed UTF-8 characters, possibly incorrectly encoded';
                 break;
             }
-            throw new \UnexpectedValueException('Incorrect composer.json file: '.$msg);
+            throw new \UnexpectedValueException('JSON Parse Error: '.$msg);
         }
 
         return $data;

tests/Composer/Test/Json/JsonFileTest.php

@@ -0,0 +1,69 @@
+<?php
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *     Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Test\Json;
+
+use Composer\Json\JsonFile;
+
+class JsonFileTest extends \PHPUnit_Framework_TestCase
+{
+    public function testParseErrorDetectExtraComma()
+    {
+        $json = '{
+        "foo": "bar",
+}';
+        $this->expectParseException('extra comma on line 2, char 21', $json);
+    }
+
+    public function testParseErrorDetectSingleQuotes()
+    {
+        $json = '{
+        \'foo\': "bar"
+}';
+        $this->expectParseException('use double quotes (") instead of single quotes (\') on line 2, char 9', $json);
+    }
+
+    public function testParseErrorDetectMissingQuotes()
+    {
+        $json = '{
+        foo: "bar"
+}';
+        $this->expectParseException('must use double quotes (") around keys on line 2, char 9', $json);
+    }
+
+    public function testParseErrorDetectArrayAsHash()
+    {
+        $json = '{
+        "foo": ["bar": "baz"]
+}';
+        $this->expectParseException('you must use the hash syntax (e.g. {"foo": "bar"}) instead of array syntax (e.g. ["foo", "bar"]) on line 2, char 16', $json);
+    }
+
+    public function testParseErrorDetectMissingComma()
+    {
+        $json = '{
+        "foo": "bar"
+        "bar": "foo"
+}';
+        $this->expectParseException('missing comma on line 2, char 21', $json);
+    }
+
+    private function expectParseException($text, $json)
+    {
+        try {
+            JsonFile::parseJson($json);
+            $this->fail();
+        } catch (\UnexpectedValueException $e) {
+            $this->assertContains($text, $e->getMessage());
+        }
+    }
+}