Item partial tuples (#348)

* Test for partial tuple validation

* Fix validation of partial tuples

When 'items' is an array of schemas, allow 'items' and 'additionalItems'
validations to pass even when the target array has fewer elements than items.

* code review tweak

Author: jlfaber

CHANGELOG.md

@@ -9,6 +9,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - Made sure we really do clear the cache when instructed to
 - It's now possible to use reserved words in property names
 - Removed support for setting "extends" to a string (it's invalid json-schema - use a "$ref" instead)
+- Relaxed 'items' and 'allowedItems' validation to permit arrays to pass even
+  when they contain fewer elements than the 'items' array.  To require full tuples,
+  use 'minItems'.
 
 ### Changed
 - Made all `validate*` methods on `JSON::Validator` ultimately call `validate!`

lib/json-schema/attributes/additionalitems.rb

@@ -11,7 +11,7 @@ def self.validate(current_schema, data, fragments, processor, validator, options
 
         case schema['additionalItems']
         when false
-          if schema['items'].length != data.length
+          if schema['items'].length < data.length
             message = "The property '#{build_fragment(fragments)}' contains additional array elements outside of the schema when none are allowed"
             validation_error(processor, message, fragments, current_schema, self, options[:record_errors])
           end

lib/json-schema/attributes/items.rb

@@ -16,6 +16,7 @@ def self.validate(current_schema, data, fragments, processor, validator, options
 
         when Array
           items.each_with_index do |item_schema, i|
+            break if i >= data.length
             schema = JSON::Schema.new(item_schema, current_schema.uri, validator)
             schema.validate(data[i], fragments + [i.to_s], processor, options)
           end

test/support/array_validation.rb

@@ -25,7 +25,9 @@ def test_items_multiple_schemas
       assert_valid schema, ['b', 1]
       assert_valid schema, ['b', 1, nil]
       refute_valid schema, [1, 'b']
-      refute_valid schema, []
+      assert_valid schema, []
+      assert_valid schema, ['b']
+      assert_valid schema, ['b', 1, 25]
     end
 
     def test_minitems
@@ -62,6 +64,8 @@ def test_additional_items_false
       }
 
       assert_valid schema, [1, 'string']
+      assert_valid schema, [1]
+      assert_valid schema, []
       refute_valid schema, [1, 'string', 2]
       refute_valid schema, ['string', 1]
     end