Add array option support for have db column matcher

lib/shoulda/matchers/active_record/have_db_column_matcher.rb

@@ -52,7 +52,7 @@ module ActiveRecord
       #
       # Use `with_options` to assert that a column has been defined with
       # certain options (`:precision`, `:limit`, `:default`, `:null`, `:scale`,
-      # or `:primary`).
+      # `:primary` or `:array`).
       #
       #     class CreatePhones < ActiveRecord::Migration
       #       def change
@@ -84,7 +84,7 @@ def have_db_column(column)
 
       # @private
       class HaveDbColumnMatcher
-        OPTIONS = %i(precision limit default null scale primary).freeze
+        OPTIONS = %i(precision limit default null scale primary array).freeze
 
         def initialize(column)
           @column = column
@@ -115,7 +115,8 @@ def matches?(subject)
             correct_default? &&
             correct_null? &&
             correct_scale? &&
-            correct_primary?
+            correct_primary? &&
+            correct_array?
         end
 
         def failure_message
@@ -258,6 +259,23 @@ def correct_primary?
           end
         end
 
+        def correct_array?
+          return true unless @options.key?(:array)
+
+          if matched_column.array? == @options[:array]
+            true
+          else
+            @missing = "#{model_class} has a db column named #{@column} "
+            @missing <<
+              if @options[:primary]
+                'that is not array, but should be'
+              else
+                'that is array, but should not be'
+              end
+            false
+          end
+        end
+
         def matched_column
           @_matched_column ||= begin
             column = model_class.columns.detect do |each|

spec/unit/shoulda/matchers/active_record/have_db_column_matcher_spec.rb

@@ -98,6 +98,20 @@
     end
   end
 
+  if database_supports_array_columns?
+    context 'with array option' do
+      it 'accepts a column that is array' do
+        expect(with_table(:tags, :string, array: true)).
+          to have_db_column(:tags).with_options(array: true)
+      end
+
+      it 'rejects a column that is not array' do
+        expect(with_table(:whatever, :string, array: false)).
+          not_to have_db_column(:whatever).with_options(array: true)
+      end
+    end
+  end
+
   context 'with invalid argument option' do
     it 'raises an error with the unknown options' do
       expect {