Merge pull request #13022 from pwnall/fixture_context

Introduce a context for rendering fixtures ERB.

4 files changed, 95 insertions, 1 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 34603b7f23..58222e8111 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,9 @@
+*   The ERB in fixture files is no longer evaluated in the context of the main
+    object. Helper methods used by multiple fixtures should be defined on the
+    class object returned by `ActiveRecord::FixtureSet.context_class`.
+
+    *Victor Costan*
+
 *   Previously, the `has_one` macro incorrectly accepted the `counter_cache`
     option, but never actually supported it. Now it will raise an `ArgumentError`
     when using `has_one` with `counter_cache`.
diff --git a/activerecord/lib/active_record/fixture_set/file.rb b/activerecord/lib/active_record/fixture_set/file.rb
index fbd7a4d891..8132310c91 100644
--- a/activerecord/lib/active_record/fixture_set/file.rb
+++ b/activerecord/lib/active_record/fixture_set/file.rb
@@ -38,7 +38,8 @@ module ActiveRecord
         end
 
         def render(content)
-          ERB.new(content).result
+          context = ActiveRecord::FixtureSet::RenderContext.create_subclass.new
+          ERB.new(content).result(context.get_binding)
         end
 
         # Validate our unmarshalled data.
diff --git a/activerecord/lib/active_record/fixtures.rb b/activerecord/lib/active_record/fixtures.rb
index 8601414209..d241788a9b 100644
--- a/activerecord/lib/active_record/fixtures.rb
+++ b/activerecord/lib/active_record/fixtures.rb
@@ -119,6 +119,23 @@ module ActiveRecord
   # perhaps you should reexamine whether your application is properly testable. Hence, dynamic values
   # in fixtures are to be considered a code smell.
   #
+  # Helper methods defined in a fixture will not be available in other fixtures, to prevent against
+  # unwanted inter-test dependencies. Methods used by multiple fixtures should be defined in a module
+  # that is included in <tt>ActiveRecord::FixtureSet.context_class</tt>.
+  #
+  # - define a helper method in `test_helper.rb`
+  #     class FixtureFileHelpers
+  #       def file_sha(path)
+  #         Digest::SHA2.hexdigest(File.read(Rails.root.join('test/fixtures', path)))
+  #       end
+  #     end
+  #     ActiveRecord::FixtureSet.context_class.send :include, FixtureFileHelpers
+  #
+  # - use the helper method in a fixture
+  #     photo:
+  #       name: kitten.png
+  #       sha: <%= file_sha 'files/kitten.png' %>
+  #
   # = Transactional Fixtures
   #
   # Test cases can use begin+rollback to isolate their changes to the database instead of having to
@@ -529,6 +546,11 @@ module ActiveRecord
       Zlib.crc32(label.to_s) % MAX_ID
     end
 
+    # Superclass for the evaluation contexts used by ERB fixtures.
+    def self.context_class
+      @context_class ||= Class.new
+    end
+
     attr_reader :table_name, :name, :fixtures, :model_class, :config
 
     def initialize(connection, name, class_name, path, config = ActiveRecord::Base)
@@ -989,3 +1011,13 @@ module ActiveRecord
       end
   end
 end
+
+class ActiveRecord::FixtureSet::RenderContext # :nodoc:
+  def self.create_subclass
+    Class.new ActiveRecord::FixtureSet.context_class do
+      def get_binding
+        binding()
+      end
+    end
+  end
+end
diff --git a/activerecord/test/cases/fixture_set/file_test.rb b/activerecord/test/cases/fixture_set/file_test.rb
index a029fedbd3..92efa8aca7 100644
--- a/activerecord/test/cases/fixture_set/file_test.rb
+++ b/activerecord/test/cases/fixture_set/file_test.rb
@@ -68,6 +68,61 @@ module ActiveRecord
         end
       end
 
+      def test_render_context_helper
+        ActiveRecord::FixtureSet.context_class.class_eval do
+          def fixture_helper
+            "Fixture helper"
+          end
+        end
+        yaml = "one:\n  name: <%= fixture_helper %>\n"
+        tmp_yaml ['curious', 'yml'], yaml do |t|
+          golden =
+              [["one", {"name" => "Fixture helper"}]]
+          assert_equal golden, File.open(t.path) { |fh| fh.to_a }
+        end
+        ActiveRecord::FixtureSet.context_class.class_eval do
+          remove_method :fixture_helper
+        end
+      end
+
+      def test_render_context_lookup_scope
+        yaml = <<END
+one:
+  ActiveRecord: <%= defined? ActiveRecord %>
+  ActiveRecord_FixtureSet: <%= defined? ActiveRecord::FixtureSet %>
+  FixtureSet: <%= defined? FixtureSet %>
+  ActiveRecord_FixtureSet_File: <%= defined? ActiveRecord::FixtureSet::File %>
+  File: <%= File.name %>
+END
+
+        golden = [['one', {
+          'ActiveRecord' => 'constant',
+          'ActiveRecord_FixtureSet' => 'constant',
+          'FixtureSet' => nil,
+          'ActiveRecord_FixtureSet_File' => 'constant',
+          'File' => 'File'
+        }]]
+
+        tmp_yaml ['curious', 'yml'], yaml do |t|
+          assert_equal golden, File.open(t.path) { |fh| fh.to_a }
+        end
+      end
+
+      # Make sure that each fixture gets its own rendering context so that
+      # fixtures are independent.
+      def test_independent_render_contexts
+        yaml1 = "<% def leaked_method; 'leak'; end %>\n"
+        yaml2 = "one:\n  name: <%= leaked_method %>\n"
+        tmp_yaml ['leaky', 'yml'], yaml1 do |t1|
+          tmp_yaml ['curious', 'yml'], yaml2 do |t2|
+            File.open(t1.path) { |fh| fh.to_a }
+            assert_raises(NameError) do
+              File.open(t2.path) { |fh| fh.to_a }
+            end
+          end
+        end
+      end
+
       private
       def tmp_yaml(name, contents)
         t = Tempfile.new name