allow multiple values for AllowValueMatcher

With the deprecation of "should_allow_values_for" there is currently no clean
way to specify multiple allowed (or forbidden) values for an attribute in a
single assertion. This can make test cases unnecessarily verbose.

This patch gives AllowValueMatcher the ability to take multiple values. The new
matcher is fully downward compatible (i.e. given a single argument it behaves
identically to the old matcher).

This matcher will stop checking for bad values when the first bad value is
encountered.

lib/shoulda/matchers/active_model/allow_value_matcher.rb

@@ -2,7 +2,10 @@ module Shoulda # :nodoc:
   module Matchers
     module ActiveModel # :nodoc:
 
-      # Ensures that the attribute can be set to the given value.
+      # Ensures that the attribute can be set to the given value or values. If
+      # multiple values are given the match succeeds only if all given values
+      # are allowed. Otherwise, the matcher fails at the first bad value in the
+      # argument list (the remaining arguments are not processed then).
       #
       # Options:
       # * <tt>with_message</tt> - value the test expects to find in
@@ -13,15 +16,16 @@ module Shoulda # :nodoc:
       #   it { should_not allow_value('bad').for(:isbn) }
       #   it { should allow_value("isbn 1 2345 6789 0").for(:isbn) }
       #
-      def allow_value(value)
-        AllowValueMatcher.new(value)
+      def allow_value(*values)
+        raise ArgumentError.new("need at least one argument") if values.empty?
+        AllowValueMatcher.new(*values)
       end
 
       class AllowValueMatcher # :nodoc:
         include Helpers
 
-        def initialize(value)
-          @value = value
+        def initialize(*values)
+          @values_to_match = values
         end
 
         def for(attribute)
@@ -39,8 +43,12 @@ module Shoulda # :nodoc:
           if Symbol === @expected_message
             @expected_message = default_error_message(@expected_message, :model_name => @instance.class.to_s.underscore, :attribute => @attribute)
           end
-          @instance.send("#{@attribute}=", @value)
-          !errors_match?
+          @values_to_match.each do |value|
+            @value = value
+            @instance.send("#{@attribute}=", @value)
+            return false if errors_match?
+          end
+          true
         end
 
         def failure_message
@@ -52,7 +60,12 @@ module Shoulda # :nodoc:
         end
 
         def description
-          "allow #{@attribute} to be set to #{@value.inspect}"
+          "allow #{@attribute} to be set to " <<
+            if @values_to_match.length > 1
+              "any of [#{@values_to_match.map {|v| v.inspect }.join(', ')}]"
+            else
+              @values_to_match.first.inspect
+            end
         end
 
         private

spec/shoulda/active_model/allow_value_matcher_spec.rb

@@ -17,6 +17,14 @@ describe Shoulda::Matchers::ActiveModel::AllowValueMatcher do
     it "should not allow a bad value" do
       @model.should_not allow_value("xyz").for(:attr)
     end
+
+    it "should allow several good values" do
+      @model.should allow_value("abcde", "deabc").for(:attr)
+    end
+
+    it "should not allow several bad values" do
+      @model.should_not allow_value("xyz", "zyx", nil, []).for(:attr)
+    end
   end
 
   context "an attribute with a format validation and a custom message" do
@@ -51,12 +59,32 @@ describe Shoulda::Matchers::ActiveModel::AllowValueMatcher do
       @model.should allow_value("12345").for(:attr)
     end
 
-    bad_values = [nil, "", "abc", "0", "50001", "123456"]
+    bad_values = [nil, "", "abc", "0", "50001", "123456", []]
+
     bad_values.each do |value|
       it "should not allow a bad value (#{value.inspect})" do
         @model.should_not allow_value(value).for(:attr)
       end
     end
+
+    it "should not allow bad values (#{bad_values.map {|v| v.inspect}.join(', ')})" do
+      @model.should_not allow_value(*bad_values).for(:attr)
+    end
   end
 
+  context "an AllowValueMatcher with multiple values" do
+    before { @matcher = allow_value("foo", "bar").for(:baz) }
+
+    it "should describe itself" do
+      @matcher.description.should eq('allow baz to be set to any of ["foo", "bar"]')
+    end
+  end
+
+  context "an AllowValueMatcher with a single value" do
+    before { @matcher = allow_value("foo").for(:baz) }
+
+    it "should describe itself" do
+      @matcher.description.should eq('allow baz to be set to "foo"')
+    end
+  end
 end