Fix deprecation warning for uniqueness matcher (Rails 4.2)

lib/shoulda/matchers/active_record/validate_uniqueness_of_matcher.rb

@@ -518,8 +518,8 @@ def update_existing_record!(value)
         end
 
         def arbitrary_non_blank_value
+          non_blank_value = dummy_value_for(@attribute)
           limit = column_limit_for(@attribute)
-          non_blank_value = 'an arbitrary value'
 
           if limit && limit < non_blank_value.length
             'x' * limit

spec/support/unit/matchers/print_warning_including.rb

@@ -11,43 +11,51 @@ def initialize(expected_warning)
 
       def matches?(block)
         @captured_stderr = collapse_whitespace(capture(:stderr, &block))
+        @was_negated = false
         captured_stderr.include?(expected_warning)
       end
 
+      def does_not_match?(block)
+        !matches?(block).tap do
+          @was_negated = true
+        end
+      end
+
       def failure_message
-        "Expected block to #{expectation}\nbut actually printed#{actual_warning}"
+        "Expected block to #{expectation}\n\nHowever, #{aberration}"
       end
-      alias_method :failure_message_for_should, :failure_message
 
       def failure_message_when_negated
-        "Expected block not to #{expectation}, but it did."
+        "Expected block not to #{expectation}\n\nHowever, #{aberration}"
       end
-      alias_method :failure_message_for_should_not,
-        :failure_message_when_negated
 
       def description
-        "should #{expectation}"
+        "should print a warning containing #{expected_warning.inspect}"
       end
 
       def supports_block_expectations?
         true
       end
 
-      protected
+      private
 
       attr_reader :expected_warning, :captured_stderr
 
-      private
+      def was_negated?
+        @was_negated
+      end
 
       def expectation
-        "print a warning including:\n  #{expected_warning}"
+        "print a warning containing:\n\n  #{expected_warning}"
       end
 
-      def actual_warning
-        if captured_stderr.empty?
-          " nothing."
+      def aberration
+        if was_negated?
+          'it did.'
+        elsif captured_stderr.empty?
+          'it actually printed nothing.'
         else
-          ":\n  #{captured_stderr}"
+          "it actually printed:\n\n  #{captured_stderr}"
         end
       end
 

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

@@ -929,11 +929,11 @@
 
         message = <<-MESSAGE
 Example did not properly validate that :attr is case-sensitively unique.
-  After taking the given Example, setting its :attr to ‹"an arbitrary
-  value"›, and saving it as the existing record, then making a new
-  Example and setting its :attr to a different value, ‹"AN ARBITRARY
-  VALUE"›, the matcher expected the new Example to be valid, but it was
-  invalid instead, producing these validation errors:
+  After taking the given Example, setting its :attr to ‹"dummy value"›,
+  and saving it as the existing record, then making a new Example and
+  setting its :attr to a different value, ‹"DUMMY VALUE"›, the matcher
+  expected the new Example to be valid, but it was invalid instead,
+  producing these validation errors:
 
   * attr: ["has already been taken"]
         MESSAGE
@@ -1355,12 +1355,12 @@ def name=(name)
 
           message = <<-MESSAGE.strip
 Example did not properly validate that :name is case-sensitively unique.
-  After taking the given Example, setting its :name to ‹"an arbitrary
-  value"› (read back as ‹"AN ARBITRARY VALUE"›), and saving it as the
-  existing record, then making a new Example and setting its :name to
-  ‹"an arbitrary value"› (read back as ‹"AN ARBITRARY VALUE"›) as well,
-  the matcher expected the new Example to be valid, but it was invalid
-  instead, producing these validation errors:
+  After taking the given Example, setting its :name to ‹"dummy value"›
+  (read back as ‹"DUMMY VALUE"›), and saving it as the existing record,
+  then making a new Example and setting its :name to ‹"dummy value"›
+  (read back as ‹"DUMMY VALUE"›) as well, the matcher expected the new
+  Example to be valid, but it was invalid instead, producing these
+  validation errors:
 
   * name: ["has already been taken"]
 
@@ -1419,6 +1419,18 @@ def name=(name)
     end
   end
 
+  context 'when the column is a boolean column' do
+    it 'accepts (and does not print a warning)' do
+      record = build_record_validating_uniqueness(attribute_type: :boolean)
+      running_validation = -> { expect(record).to validate_uniqueness }
+      message =
+        'You attempted to assign a value which is not explicitly `true` or ' +
+        '`false`'
+
+      expect(&running_validation).not_to print_warning_including(message)
+    end
+  end
+
   let(:model_attributes) { {} }
 
   def default_attribute