fix missing $id in root schema

Author: Eomm

ref-resolver.js

@@ -64,7 +64,7 @@ function jsonSchemaResolver (options) {
     // represent a valid URI-reference [RFC3986].  This value SHOULD be
     // normalized, and SHOULD NOT be an empty fragment <#> or an empty
     // string <>.
-    const appUri = URI.parse(rootSchema.$id)
+    const appUri = URI.parse(rootSchema.$id || 'application.uri')
     appUri.fragment = undefined // remove fragment
     debug('Found app URI %o', appUri)
 
@@ -74,7 +74,9 @@ function jsonSchemaResolver (options) {
     }
 
     const baseUri = URI.serialize(appUri) // canonical absolute-URI
-    rootSchema.$id = baseUri // fix the schema $id value
+    if (rootSchema.$id) {
+      rootSchema.$id = baseUri // fix the schema $id value
+    }
     rootSchema[kIgnore] = true
 
     mapIds(ee, appUri, rootSchema)

test/ref-resolver.test.js

@@ -165,3 +165,24 @@ test('dont resolve external schema missing #2', t => {
   const out = resolver.resolve(schema)
   t.deepEquals(schema, out, 'the output is the same input not modified')
 })
+
+test('missing id in root schema', t => {
+  t.plan(3)
+  const schema = {
+    $ref: 'relativePerson'
+  }
+
+  const opts = {
+    externalSchemas: [
+      factory('relativeId-externalAndLocalRef'),
+      factory('relativeId-noRef')
+    ]
+  }
+
+  const resolver = RefResolver()
+  const out = resolver.resolve(schema, opts)
+  save(out)
+  t.deepEquals(schema, out, 'the output is the same input modified')
+  t.ok(out.definitions, 'definitions has been added')
+  t.deepEquals(Object.values(out.definitions), opts.externalSchemas, 'external schema has been added to definitions')
+})