Validate enum column is an integer in define_enum_for

If your ActiveRecord model stores its `enum` data in a non-integer
column, ActiveRecord will save the data without error. However, when you
access the attribute on the record after saving, AR will look for the
string to what it expects to be a list of numbers and return `nil`
rather than the mapped value.

This change adds a third criterion to the `define_enum_for` matcher,
verifying that the underlying database column has a `sql_type` of
`"integer"`.

Fix #827.

lib/shoulda/matchers/active_record/define_enum_for_matcher.rb

@@ -64,7 +64,7 @@ def with(expected_enum_values)
 
         def matches?(subject)
           @model = subject
-          enum_defined? && enum_values_match?
+          enum_defined? && enum_values_match? && column_type_is_integer?
         end
 
         def failure_message
@@ -84,6 +84,8 @@ def description
             desc << " with #{options[:expected_enum_values]}"
           end
 
+          desc << " and store the value in a column with an integer type"
+
           desc
         end
 
@@ -111,6 +113,16 @@ def enum_values_match?
           expected_enum_values.empty? || actual_enum_values == expected_enum_values
         end
 
+        def matched_column
+          @_matched_column ||= begin
+            @model.class.columns.detect { |each| each.name == attribute_name.to_s }
+          end
+        end
+
+        def column_type_is_integer?
+          matched_column.sql_type == "integer"
+        end
+
         def hashify(value)
           if value.nil?
             return {}

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

@@ -6,7 +6,7 @@
       it 'rejects' do
         record = record_with_array_values
         plural_enum_attribute = enum_attribute.to_s.pluralize
-        message = "Expected #{record.class} to define :#{plural_enum_attribute} as an enum"
+        message = "Expected #{record.class} to define :#{plural_enum_attribute} as an enum and store the value in a column with an integer type"
         assertion = -> {
           expect(record).to define_enum_for(plural_enum_attribute)
         }
@@ -19,7 +19,25 @@
         model = define_model :example do
           def self.statuses; end
         end
-        message = "Expected #{model} to define :statuses as an enum"
+        message = "Expected #{model} to define :statuses as an enum and store the value in a column with an integer type"
+        assertion = -> {
+          expect(model.new).to define_enum_for(:statuses)
+        }
+        expect(&assertion).to fail_with_message(message)
+      end
+    end
+
+    context 'if the column storing the attribute is not an integer type' do
+      it 'rejects' do
+        _enum_attribute = enum_attribute
+        model = define_model(
+          :record_with_array_values,
+          _enum_attribute => { type: :string },
+        ) do
+          enum(_enum_attribute => %w(published unpublished draft))
+        end
+
+        message = "Expected #{model} to define :statuses as an enum and store the value in a column with an integer type"
         assertion = -> {
           expect(model.new).to define_enum_for(:statuses)
         }
@@ -33,15 +51,23 @@ def self.statuses; end
       end
 
       it "rejects a record where the attribute is not defined as an enum" do
-        message = "Expected #{record_with_array_values.class} to define :#{non_enum_attribute} as an enum"
+        message = "Expected #{record_with_array_values.class} to define :#{non_enum_attribute} as an enum and store the value in a column with an integer type"
 
         expect do
           expect(record_with_array_values).to define_enum_for(non_enum_attribute)
         end.to fail_with_message(message)
       end
 
       it "rejects a record where the attribute is not defined as an enum with should not" do
-        message = "Did not expect #{record_with_array_values.class} to define :#{enum_attribute} as an enum"
+        message = "Did not expect #{record_with_array_values.class} to define :#{enum_attribute} as an enum and store the value in a column with an integer type"
+
+        expect do
+          expect(record_with_array_values).to_not define_enum_for(enum_attribute)
+        end.to fail_with_message(message)
+      end
+
+      it 'rejects a record where the saved attribute does not come back out after saving' do
+        message = "Did not expect #{record_with_array_values.class} to define :#{enum_attribute} as an enum and store the value in a column with an integer type"
 
         expect do
           expect(record_with_array_values).to_not define_enum_for(enum_attribute)
@@ -57,15 +83,15 @@ def self.statuses; end
         end
 
         it "accepts a record where the attribute is not defined as an enum" do
-          message = %{Expected #{record_with_array_values.class} to define :#{non_enum_attribute} as an enum with ["open", "close"]}
+          message = %{Expected #{record_with_array_values.class} to define :#{non_enum_attribute} as an enum with ["open", "close"] and store the value in a column with an integer type}
 
           expect do
             expect(record_with_array_values).to define_enum_for(non_enum_attribute).with(["open", "close"])
           end.to fail_with_message(message)
         end
 
         it "accepts a record where the attribute is defined as an enum but the enum values do not match" do
-          message = %{Expected #{record_with_array_values.class} to define :#{enum_attribute} as an enum with ["open", "close"]}
+          message = %{Expected #{record_with_array_values.class} to define :#{enum_attribute} as an enum with ["open", "close"] and store the value in a column with an integer type}
 
           expect do
             expect(record_with_array_values).to define_enum_for(enum_attribute).with(["open", "close"])
@@ -83,15 +109,15 @@ def self.statuses; end
         end
 
         it "accepts a record where the attribute is defined as an enum but the enum values do not match" do
-          message = %{Expected #{record_with_hash_values.class} to define :#{enum_attribute} as an enum with {:active=>5, :archived=>10}}
+          message = %{Expected #{record_with_hash_values.class} to define :#{enum_attribute} as an enum with {:active=>5, :archived=>10} and store the value in a column with an integer type}
 
           expect do
             expect(record_with_hash_values).to define_enum_for(enum_attribute).with(active: 5, archived: 10)
           end.to fail_with_message(message)
         end
 
         it "rejects a record where the attribute is not defined as an enum" do
-          message = %{Expected #{record_with_hash_values.class} to define :record_with_hash_values as an enum with {:active=>5, :archived=>10}}
+          message = %{Expected #{record_with_hash_values.class} to define :record_with_hash_values as an enum with {:active=>5, :archived=>10} and store the value in a column with an integer type}
 
           expect do
             expect(record_with_hash_values)
@@ -111,14 +137,20 @@ def non_enum_attribute
 
     def record_with_array_values
       _enum_attribute = enum_attribute
-      define_model :record_with_array_values do
+      define_model(
+        :record_with_array_values,
+        _enum_attribute => { type: :integer },
+      ) do
         enum(_enum_attribute => %w(published unpublished draft))
       end.new
     end
 
     def record_with_hash_values
       _enum_attribute = enum_attribute
-      define_model :record_with_hash_values do
+      define_model(
+        :record_with_hash_values,
+        _enum_attribute => { type: :integer },
+      ) do
         enum(_enum_attribute => { active: 0, archived: 1 })
       end.new
     end