Support nested -erences (#188)

Author: scmorse

README.md

@@ -402,6 +402,38 @@ const externalSchema = {
   strings: require('./string-def.json')
 }
 
+const stringify = fastJson(schema, { schema: externalSchema })
+```
+External definitions can also reference each other.
+Example:
+```javascript
+const schema = {
+  title: 'Example Schema',
+  type: 'object',
+  properties: {
+    foo: {
+      $ref: 'strings#/definitions/foo'
+    }
+  }
+}
+
+const externalSchema = {
+  strings: {
+    definitions: {
+      foo: {
+        $ref: 'things#/definitions/foo'
+      }
+    }
+  },
+  things: {
+    definitions: {
+      foo: {
+        type: 'string'
+      }
+    }
+  }
+}
+
 const stringify = fastJson(schema, { schema: externalSchema })
 ```
 

index.js

@@ -310,7 +310,7 @@ function addPatternProperties (schema, externalSchema, fullSchema) {
   `
   Object.keys(pp).forEach((regex, index) => {
     if (pp[regex].$ref) {
-      pp[regex] = refFinder(pp[regex].$ref, fullSchema, externalSchema, fullSchema)
+      pp[regex] = refFinder(pp[regex].$ref, fullSchema, externalSchema)
     }
     var type = pp[regex].type
     code += `
@@ -513,7 +513,8 @@ function refFinder (ref, schema, externalSchema) {
       }
     }
   }
-  return (new Function('schema', code))(schema)
+  const result = (new Function('schema', code))(schema)
+  return result.$ref ? refFinder(result.$ref, schema, externalSchema) : result
 }
 
 function sanitizeKey (key) {

test/ref.test.js

@@ -804,3 +804,45 @@ test('ref external to relative definition', (t) => {
 
   t.equal(output, '{"fooParent":{"foo":"bar"}}')
 })
+
+test('ref to nested ref definition', (t) => {
+  t.plan(2)
+
+  const externalSchema = {
+    'a:b:c1': {
+      $id: 'a:b:c1',
+      type: 'object',
+      definitions: {
+        foo: { $ref: 'a:b:c2#/definitions/foo' }
+      }
+    },
+    'a:b:c2': {
+      $id: 'a:b:c2',
+      type: 'object',
+      definitions: {
+        foo: { type: 'string' }
+      }
+    }
+  }
+
+  const schema = {
+    type: 'object',
+    required: ['foo'],
+    properties: {
+      foo: { $ref: 'a:b:c1#/definitions/foo' }
+    }
+  }
+
+  const object = { foo: 'foo' }
+  const stringify = build(schema, { schema: externalSchema })
+  const output = stringify(object)
+
+  try {
+    JSON.parse(output)
+    t.pass()
+  } catch (e) {
+    t.fail()
+  }
+
+  t.equal(output, '{"foo":"foo"}')
+})