Add test

tests/IssueTest.php

@@ -0,0 +1,13 @@
+<?php
+
+use cebe\openapi\Reader;
+
+class IssueTest extends \PHPUnit\Framework\TestCase
+{
+    // https://github.com/cebe/php-openapi/issues/175
+    public function test175UnableToReferenceOtherLocalJsonFile()
+    {
+        $openapi = Reader::readFromJsonFile(__DIR__.'/data/issue/175/spec.json');
+        $this->assertInstanceOf(\cebe\openapi\SpecObjectInterface::class, $openapi);
+    }
+}

tests/data/issue/175/401.json

@@ -0,0 +1,20 @@
+{
+    "description": "401 response",
+    "content": {
+        "application/json": {
+            "schema": {
+                "properties": {
+                    "message": {
+                        "type": "string"
+                    }
+                },
+                "required": [
+                    "message"
+                ]
+            },
+            "example": {
+                "message": "Unauthenticated."
+            }
+        }
+    }
+}

tests/data/issue/175/spec.json

@@ -0,0 +1,20 @@
+{
+    "openapi": "3.0.0",
+    "info": {
+        "title": "My API",
+        "version": "1, 2"
+    },
+    "paths": {
+        "/v1/users/profile": {
+            "get": {
+                "operationId": "V1GetUserProfile",
+                "summary": "Returns the user profile",
+                "responses": {
+                    "401": {
+                        "$ref": "./401.json"
+                    }
+                }
+            }
+        }
+    }
+}