Add Composer autoloading functions and PHPStan for testing

vendor/nikic/php-parser/test/PhpParser/JsonDecoderTest.php

@@ -0,0 +1,43 @@
+<?php declare(strict_types=1);
+
+namespace PhpParser;
+
+class JsonDecoderTest extends \PHPUnit\Framework\TestCase
+{
+    public function testRoundTrip() {
+        $code = <<<'PHP'
+<?php
+// comment
+/** doc comment */
+function functionName(&$a = 0, $b = 1.0) {
+    echo 'Foo';
+}
+PHP;
+
+        $parser = new Parser\Php7(new Lexer());
+        $stmts = $parser->parse($code);
+        $json = json_encode($stmts);
+
+        $jsonDecoder = new JsonDecoder();
+        $decodedStmts = $jsonDecoder->decode($json);
+        $this->assertEquals($stmts, $decodedStmts);
+    }
+
+    /** @dataProvider provideTestDecodingError */
+    public function testDecodingError($json, $expectedMessage) {
+        $jsonDecoder = new JsonDecoder();
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage($expectedMessage);
+        $jsonDecoder->decode($json);
+    }
+
+    public function provideTestDecodingError() {
+        return [
+            ['???', 'JSON decoding error: Syntax error'],
+            ['{"nodeType":123}', 'Node type must be a string'],
+            ['{"nodeType":"Name","attributes":123}', 'Attributes must be an array'],
+            ['{"nodeType":"Comment"}', 'Comment must have text'],
+            ['{"nodeType":"xxx"}', 'Unknown node type "xxx"'],
+        ];
+    }
+}