Added the error matcher.

Author: stas

README.md

@@ -46,6 +46,7 @@ Available matchers:
 * `expect(document).to have_meta('foo' => 'bar', 'fum' => 'baz').exactly`
 * `expect(document).to have_jsonapi_object`
 * `expect(document).to have_jsonapi_object('version' => '1.0')`
+* `expect(document).to have_error('status' => '422')`
 
 ### On matcher arguments...
 

lib/jsonapi/rspec.rb

@@ -8,6 +8,7 @@
 require 'jsonapi/rspec/links'
 require 'jsonapi/rspec/meta'
 require 'jsonapi/rspec/jsonapi_object'
+require 'jsonapi/rspec/errors'
 
 RSpec.configure do |c|
   c.add_setting :jsonapi_indifferent_hash, default: false

lib/jsonapi/rspec/errors.rb

@@ -0,0 +1,19 @@
+module JSONAPI
+  module RSpec
+    module Meta
+      ::RSpec::Matchers.define :have_error do |error|
+        match do |actual|
+          actual = JSONAPI::RSpec.as_indifferent_hash(actual)
+          return false unless actual.key?('errors')
+          return false unless actual['errors'].is_a?(Array)
+
+          return true if actual['errors'].any? && error.nil?
+
+          error = JSONAPI::RSpec.as_indifferent_hash(error)
+
+          actual['errors'].any? { |actual_error| error <= actual_error }
+        end
+      end
+    end
+  end
+end

spec/jsonapi/errors_spec.rb

@@ -0,0 +1,40 @@
+require 'spec_helper'
+
+RSpec.describe JSONAPI::RSpec, '#have_error' do
+  let(:doc) do
+    {
+      'errors' => [
+        {
+          'status' => '422',
+          'source' => { 'pointer' => '/data/attributes/firstName' },
+          'title' => 'Invalid Attribute',
+          'detail' => 'First name must contain at least three characters.'
+        }
+      ]
+    }
+  end
+
+  context 'when providing no value' do
+    it 'succeeds when errors are present' do
+      expect(doc).to have_error
+    end
+
+    it 'fails when errors are missing' do
+      expect({}).not_to have_error
+      expect({ 'errors' => [] }).not_to have_error
+    end
+  end
+
+  context 'when providing a value' do
+    it do
+      expect(doc).to have_error(
+        'status' => '422',
+        'source' => { 'pointer' => '/data/attributes/firstName' }
+      )
+    end
+
+    it 'fails when meta is absent' do
+      expect(doc).not_to have_error({ 'status' => '500' })
+    end
+  end
+end