support for empty schemas in additionalProperties (#294)

Author: sinclairzx81

index.js

@@ -442,6 +442,11 @@ function addPatternProperties (location) {
           ${addComma}
           json += $asString(keys[i]) + ':' + $asBoolean(obj[keys[i]])
       `
+    } else if (type === undefined) {
+      code += `
+          ${addComma}
+          json += $asString(keys[i]) + ':' + $asAny(obj[keys[i]])
+      `
     } else {
       code += `
         throw new Error('Cannot coerce ' + obj[keys[i]] + ' to ' + ${JSON.stringify(type)})
@@ -535,6 +540,11 @@ function additionalProperty (location) {
         ${addComma}
         json += $asString(keys[i]) + ':' + $asBoolean(obj[keys[i]])
     `
+  } else if (type === undefined) {
+    code += `
+        ${addComma}
+        json += $asString(keys[i]) + ':' + $asAny(obj[keys[i]])
+    `
   } else {
     code += `
         throw new Error('Cannot coerce ' + obj[keys[i]] + ' to ' + ${JSON.stringify(type)})

test/additionalProperties.test.js

@@ -161,6 +161,31 @@ test('additionalProperties - array coerce', (t) => {
   t.equal('{"foo":["t","r","u","e"],"ofoo":[],"arrfoo":["1","2"],"objfoo":[]}', stringify(obj))
 })
 
+test('additionalProperties with empty schema', (t) => {
+  t.plan(1)
+  const stringify = build({
+    type: 'object',
+    additionalProperties: {}
+  })
+
+  const obj = { a: 1, b: true, c: null }
+  t.equal('{"a":1,"b":true,"c":null}', stringify(obj))
+})
+
+test('additionalProperties with nested empty schema', (t) => {
+  t.plan(1)
+  const stringify = build({
+    type: 'object',
+    properties: {
+      data: { type: 'object', additionalProperties: {} }
+    },
+    required: ['data']
+  })
+
+  const obj = { data: { a: 1, b: true, c: null } }
+  t.equal('{"data":{"a":1,"b":true,"c":null}}', stringify(obj))
+})
+
 test('nested additionalProperties', (t) => {
   t.plan(1)
   const stringify = build({